Levels of respirable dust and respirable crystalline silica at construction sites RR878

Health and Safety
Executive
Levels of respirable dust and respirable
crystalline silica at construction sites
Prepared by the Health and Safety Laboratory
for the Health and Safety Executive 2011
RR878
Research Report
Health and Safety
Executive
Levels of respirable dust and respirable
crystalline silica at construction sites
Peter Stacey, Andrew Thorpe & Paul Roberts
Harpur Hill
Buxton
Derbyshire
SK17 9JN
The purpose of this pilot study was to assess the potential for inadvertent exposure of the public to
respirable crystalline silica (RCS) from construction activities.
The study assessed the respirable dust (RD) from, demolition, block cutting, road building, general
construction activities and city centre air from 13 visits to 7 sites. In total, 48 samples from the construction
activities and 11 city centre air samples, for comparison, were collected.
The results obtained for RD and RCS were generally very low. Only 10 % of results (from two sites) for
RCS were above 0.01 mg.m-3, which is 10 % of the current Workplace Exposure Limit (WEL) for RCS.
The majority of visits showed evidence of some transport of RCS across the site and potentially into
public areas. The main crystalline components of the city centre air sample were generally the same as the
components of the samples taken at the construction sites.
This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents,
including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily
reflect HSE policy.
HSE Books
© Crown copyright 2011
First published 2011
You may reuse this information (not including logos) free of
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[email protected].
ACKNOWLEDGEMENTS:
Special thanks are given to Mr David Bradley (HSE),
Ms Jan Foers (HSE) Ms Carol Southerd (HSE) the Sheffield
Area Office who helped identify several of the sites for this
report. Dr Colin Davy (HSE) is thanked for his support for
this project and Dr Dave Mark for his helpful suggestions.
Mr Andrew Thorpe (HSL) is thanked for this work in calibrating
the samplers and ensuring the pumps worked for a full
8 hours. Mr Paul Roberts (HSL) is thanked for his support and
work on the site visits. Thanks are also given to the many local
authorities helped with this work and the companies for their
cooperation by providing safe access to the sites and facilities.
Company names are not mentioned in the report to preserve
their confidentiality.
ii
CONTENTS 1 INTRODUCTION......................................................................................... 1
1.1
Respirable dust........................................................................................ 2
1.2
Previous evidence ................................................................................... 2
2 AIR SAMPLING STRATEGY...................................................................... 3
2.1
The equipment......................................................................................... 3
2.2
Calibration of sampler for the respirable fraction ..................................... 3
2.3
Variability of the five samplers ................................................................. 5
2.4
Monitoring strategy .................................................................................. 5
3 ANALYSIS STRATEGY.............................................................................. 7
3.1
Gravimetric analysis for respirable dust................................................... 7
3.2
RCS analysis method for ambient samples ............................................. 7
4 DESCRIPTION OF CONSTRUCTION SITES AND RESULTS ................ 10
4.1
Site 1: General Construction Activities................................................... 10
4.2
Site 2: Demolition .................................................................................. 13
4.3
Site 3: City Centre ring road Construction ............................................. 18
4.4
Site 4: Street block cutting ..................................................................... 23
4.5
Site 5: Street block cutting ..................................................................... 25
4.6
Site 6: Rubble Clearance from Demolition............................................. 27
4.7
Site 7: Demolition of College ................................................................. 30
5
COMPARISON WITH TEOM MEASUREMENTS..................................... 34
6
CRYSTALLINE COMPONENTS OF URBAN AIR ................................... 35
7 DISCUSSION............................................................................................ 38
7.1
Summary of results................................................................................ 38
7.2
Respirable Dust ..................................................................................... 39
7.3
Weight of dust recovered from ashing ................................................... 40
7.4
Respirable Crystalline Silica .................................................................. 40
7.5
Transport of dust across the sites.......................................................... 41
8
CONCLUSIONS........................................................................................ 44
9
REFERENCES.......................................................................................... 46
10
APPENDICES 1: XRD CALIBRATIONS............................................... 48
11
11.1
11.2
11.3
11.4
11.5
11.6
APPENDIX 2 ......................................................................................... 49
Site 1 Construction ................................................................................ 49
Site 2 Demolition ................................................................................... 51
Site 3: Ring road construction................................................................ 55
site 4: Block cutting................................................................................ 60
Site 5: Block Cutting .............................................................................. 63
Site 6: Rubble Clearance....................................................................... 64
iii
11.7
iv
Site 7: Demolition .................................................................................. 66
EXECUTIVE SUMMARY
Objectives
This work was a study to estimate inadvertent exposure of people to resiprable dust and
respirable crystalline silica (RCS) from construction activities in the urban environment.
Main Findings
HSE holds much information about construction sites, however the detail of the information
was not sufficient to allow it to be used to identify sites for this type of project, where such a
specific activity is evaluated.
All operators at the sites were employing what they perceived as 'best' health and safety
practice. It was noted that some controls, such as a hand pressurised water containers, do not
work continuously because there is no indicator to signify when pressure is low. The
intermittent effectiveness of these controls may increase worker exposure, but this was not
confirmed by this study.
The air concentrations for respirable dust obtained using the HSL sampler conforming to the
occupational hygiene sampling convention were comparable with the results obtained by the
local authority or UK air-monitoring network Tapered Element Oscillating Microbalance
(TEOM) site measuring the environmental health related fraction PM10 (uncorrected by the
factor 1.3). The regression coefficient (r2) excluding extreme values was 0.92.
The main crystalline components of urban air samples are quartz (SiO2), calcite (CaCO3), halite
(NaCl), anhydrite (CaSO4) and/or calcium sulphate hydrate (CaSO40.5H2O). Some urban air
samples also showed peaks that indicated the presence of clays (illite and kaolinite) and
probably hematite (Fe2O3). Many of the samples after ashing in a plasma-asher were orange in
colour, which may confirm the presence of the hematite or another iron oxide.
Generally, the crystalline components on site mirrored the components in the urban air. This
may indicate that construction activities, the natural geology, or dust from buildings in the area
contribute to the mineral composition of an urban air sample. Samples from larger demolition
sites also indicated the presence of some calcium silicates common to concretes and portlandite
(Ca(OH)2).
On average, the majority of the sample (by mass) from the urban air, general construction
activities and road building operations was combustible or volatile (57 – 73 %). indicating it
was probably mostly pollen or diesel fume. The samples from block cutting and demolition
activities were mostly non-combustible/non-volatile material (53 – 58%). Indicating a higher
mineral content and therefore associated with the activity being monitored.
Overall, about 20 % of results (for an 8 – hour sample) exceeded the ambient UK air quality
value for PM10 of 50 µg.m-3.
Despite dust controls, large-scale demolition projects, with excavators, have the potential to
produce air concentrations of respirable dust in excess of 50 µg.m-3 (Maximum 226 µg.m-3).
This is probably because the contractors find it difficult to introduce effective and consistent
dust controls because of the scale of the task.
The results for RCS and respirable dust were generally low for all the activities. Several
samples from monitoring block cutting and demolition also obtained results for RCS in excess
of 10 µg.m-3, which was probably due to inconsistent suppression of dust by the control. Despite
the controls and practices employed by workers cutting blocks and bricks with cut-off saws, a
v
couple of results from samplers (about 5 m from the activity) obtained results in excess of 10
µg.m-3. This may indicate that the controls used with cut-off saws are not meeting the
requirements for effective suppression of dust specified in A Thorpe et al (1999).
Most sites (9 in 11 sites with reasonable data) showed evidence of the transport of RCS across
the site to boundary and potentially into public areas.
RCS was identified in some of the urban air samples, although in most samples only one of the
three peaks used for quantification was present. The estimated range of values for RCS from the
urban air samplers was 0.1 – 0.44 µg.m-3 and the maximum proportion of RCS in the respirable
dust is estimated as 2 %.
Summary
The air concentration values for RCS at the boundary of construction sites are low and rarely
exceed 1/10 th of the current workplace exposure limit of 0.1 mg.m-3 (100 µg.m-3). This level of
exposure to RCS would only make a significant contribution to a worker’s exposure if the WEL
were lowered to 50 µg.m-3. It is likely that an individual, living in very close proximity (< 50 m)
to a very large scale demolition, may obtain a measurable but very low exposure to RCS,
however, demolition activities of short duration should not have a significant impact on their
health since this is dependent on a long term exposure (approximately 15 – 20 years).
Recommendations
This was a small study to ascertain if levels of respirable dust and RCS at site boundaries are
potentially significant, so the recommendations are limited, because they are based on small
numbers of data.
The results from this study indicate that dust control may still be poor with very large-scale
demolition activities and that this area may warrant further investigation. It is proposed to discus
these results with other researchers in the Building Research Establishment (BRE).
vi
1
INTRODUCTION
Inhalation of respirable crystalline silica (RCS) is known to cause a disease called silicosis and
cancer and it is thought to contribute to a condition known as chronic obstructive pulmonary
disease (COPD). Workers exposed to RCS are one of the largest groups of workers at risk from
exposure to a hazardous substance. In 1992 there were estimated to be about 100,000 workers
potentially exposed to RCS. In 2006, the workplace exposure limit (WEL) for RCS was
reduced to 100 µg.m-3 and there is pressure to lower it further to 50 µg.m-3 as epidemiological
data suggest there is no known level of exposure at which silicosis does not occur. On agreeing
the reduced WEL in 2006, the HSC tasked its Advisory Committee on Toxic Substances
(ACTS) to review the measurement issues that precluded any further reduction of the WEL at
that time, with a view to reducing the WEL further once they had been resolved. As exposure
limits are lowered it becomes increasing important to understand if the background levels of
RCS in air contribute to an individual’s personal exposure and very little information existed on
background levels at the time of the publication of this report.
There is concern over the issue of exposure of people, to respirable dust (RD) and RCS, when
they are close to but not involved in work activities, e.g. people living close by or workers
involved in other activities that do not generate RCS. Work activities; such as those to maintain
services, roadways and buildings, generate respirable crystalline silica (RCS). In addition, many
major construction activities take place in cities and most construction activities involve
working with materials containing crystalline silica. It is possible, if the WEL is reduced to 50
µg.m-3 or below, that some peak emissions from sources other than the immediate work activity
may significantly contribute to an individual's exposure. Recent papers E Bontempi et al (2008)
and V Esteve et al. (1997) have shown that RCS is a potentially significant proportion of the
crystalline content of an environmental air sample. Whilst we are able to estimate the exposure
to RCS of an individual at work from past data, little is known about the inadvertent exposure of
people who are close to but not involved in the work activity. Local authorities do not measure
respirable dust (RD) to the same specification that is used for occupational hygiene
measurements or RCS and little information exists in literature.
This pilot study conducted 13 visits to 7 sites, which sampled the activities listed in Table 1 to
assess the potential exposure of people to respirable dusts and RCS emitted from construction
activities.
Table 1: Work tasks sampled
Work Tasks
General construction
Demolition
Block cutting
Road building
Number of visits
2
7
2
2
The types of work are slightly biased towards demolition sites. This is partially due to the
limited availability of information about the work activities and poor reliability of the starting
dates for tasks potentially generating silica dust within a particular project. The more specialist
demolition companies provided an effective liaison for this specific activity. The majority of the
work in this report took place in 2009, during which an economic crisis prevented many
projects from progressing. Heavy rain during the year also hampered the available sampling
opportunities, since the equipment could not be used. The rainfall in the United Kingdom over
the summer months of June, July and August was 140% more than the long-term average for the
years 1971 – 2000 (Met Office 2009)
1
1.1
RESPIRABLE DUST
The particle size fractions sampled in environmental science are different from those sampled
for occupational hygiene work. The target specification for instruments sampling the respirable
fraction for occupational hygiene purposes is specified in EN481 (1993) and is based on
sampling a distribution of particles (approximately < 10 µm) with a median diameter of 4.3 µm,
whilst the environmental fractions have are based on particle distributions with median
diameters of 10 µm (PM10) and 2.5µm (PM2.5). The relationship between the three different
dust fractions is shown in Figure 1.
Figure 1 Definitions of particle size dust fractions
1.2
PREVIOUS EVIDENCE
The limited information about the ambient levels of respirable dust and RCS, was reviewed by
Mark et al (2009). Mentioned in the review is the work of Moore (1999) who estimated that
about 10 % of a background ambient dust concentration of 40 µg.m-3 could be crystalline silica
(CS), although it is likely that the particle size distribution of the dust referred to in the paper by
Moore is total suspended particulate (TSP) and that the respirable dust levels could be lower.
More recently a report examining the mineral dust in urban air of Beijing (Whitaker 2003) also
estimated the concentration of quartz in air as 10 % on one of its samples, although this city is
known for its experience of dust storms. Shiraki and Holmen (2002) examined the crystalline
silica content in PM 10 samples close to crushing and screening plants of a sand and gravel
facility in California. This work obtained CS levels of about 60 µg.m-3 near the work activity
and levels of 5 µg.m-3 1000 m upwind of the site and ~ 9 µg.m-3 down wind of the site. In
addition to the documents mentioned by Mark et al (2009) the World health Organisation has
published a review (Rice 2000) concerning the health effects of the respirable quartz which
refers to work by Davis et al (1984) where the results for the quantification of CS from a single
PM 10 sample range from 0 to 15.8 µg.m-3. In the most recent work by Mark et al (2009)
examining the ambient RCS levels in levels in five quarries only 5 out of 120 (4%) of
measurements were above 10 µg.m-3, the highest was approximately 21 µg.m-3. This study
examines the ambient levels of RD and RCS around a number of construction sites where
potentially dusty activities were taking place.
2
2
2.1
AIR SAMPLING STRATEGY THE EQUIPMENT
This project used the samplers developed for the HSE survey of quarries and is described in
detail in Mark et al (2009) (Figure 2). These samplers had a flow rate of 52 litres/minute and
would sample for a working period of approximately 7 – 8 hours at each site. Air is sampled
through louvered plates and size selective inlet onto a 60 mm diameter mixed cellulose ester
(MCE) filter with a 2 µm pore size. Selection of the respirable fraction on the filter was
achieved using a 10 mm thick layer of 45 ppi (pores per inch) foam and a single 10 mm layer of
60 ppi foam. The 60 ppi foam placed on top of the 45 ppi foam in the sampling was separated
from the foams by a course metal grid. Rotheroe and Mitchell L60 rotary vane sampling pumps
provide the flow rate. They were originally supplied to the HSL Occupational Hygiene Unit and
were surplus to requirements. Batteries were used because it is difficult to obtain mains supply.
Initially, two 12v high capacity lead acid leisure batteries were used to power the pump through
a 12v dc to 240v power converter. However, in the initial phase of this project the batteries
failed to run for the full time in laboratory conditions. The run time of the apparatus was
improved through the purchase of new batteries and by adapting the boxes to fit three in
parallel. The sampling flow was monitored with an in line rotameter on the outside of the
enclosure that was marked indicating the specified flow rate. Restricting the diameter of the
exhaust tubing with a clip controlled the flow rate through the filter. The rotameter was
calibrated by checking the air flowing through the sampler entry with a calibrated gas meter.
.
Figure 2 A high volume sampler for ambient respirable dust
2.2
CALIBRATION OF SAMPLER FOR THE RESPIRABLE FRACTION
2.2.1
Sampling efficiency
It was necessary to recheck the performance of the foams used for size selection because a year
had passed since the system was last used and new foams were purchased. This was carried out
using the calm air dust chamber, which is the standard apparatus used in HSL for determining
3
the size selective performance of sampling apparatus (Kenny and Liden 1991). Two identical
inlets, one with the size selective foam and the other empty, sample aerosols of glass spheres
with a known particle size distribution. The glass sphere particles penetrating the inlets are
themselves sampled by an Aerodynamic Particle Sizer (APS), which gives a number based
aerodynamic size distribution. By comparing the size distributions in the inlet with and without
the foams, the size selective performance of the foam as a respirable size selector can be
determined. The results are given in Figure 3.
1.20
Foam Penetration
Fractional penetration
1.00
CEN 481 (respirable)
0.80
0.60
0.40
0.20
0.00
0
2
4
6
8
10
12
14
Aerodynamic diameter (µm)
Figure 3 Penetration curve
45ppi 20mm thick & 60ppi 10mm thick porous foam
It can be seen that the performance of the size selective foam is close to the target respirable
convention (EN 481, 1993). However, Figure 3 also suggests that this sampler may slightly
under sample the larger particle sizes (> 6µm) within the respirable size range, which is
important for XRD analysis since smaller particles are less crystalline and contribute less
signal/mass to the measurement. The mass median aerodynamic diameter (D50) from this work
is 4.35 µm compared with 4.44 µm in the previous work reported by Mark et al (2009). The
difference between the sampling of the foam for respirable dust and the ideal respirable dust
sampler conforming to EN 481 is described in Table 2.
4
Table 2: Difference of foam selector from the ideal respirable dust sampler
Mass Median Aerodynamic
Diameter (MMAD) µm
Geometric Size Standard
Deviation (GSTDEV) µm
Difference (%)
5
2
6.21
5
3
4.54
10
2
-0.95
10
3
4.36
20
2
-9.61
20
3
3.59
30
2
-17.30
30
3
2.66
40
2
-23.84
40
3
1.70
Note: The MMAD and GSTDEV are the mass median aerodynamic diameter and geometric standard deviation of
different aerosols that the sampler is expected to encounter.
Most differences are less than 10 %, except from some aerosols with a MMAD greater than 30
µm.
2.3
VARIABILITY OF THE FIVE SAMPLERS
The five samplers were placed together in a laboratory space and run for 27 hours. Gravimetric
analysis of the filters showed a precision of ± 5 % from an average mass of 400 µg. The air
concentration of respirable dust collected was about 5 µg.m-3.
2.4
MONITORING STRATEGY
Five samplers were available for each site. Where space allowed, three samplers were placed
down wind of the site and one up wind. The fifth sampler was located in HSL’s mobile
laboratory and was placed in a convenient position near the centre of the closest major urban
conurbation close to sites unaffected by construction activities. The fifth sampler provided the
samples identified as ‘urban air’ and would be used to determine a range of levels of respirable
dust in the ‘urban air’ unaffected by the construction sites and to compare the respirable dust
results obtained with HSL sampler with the PM10 values obtained by the local authority to assess
any differences. When possible the sampler was located next to the local authority’s or the
national UK air-monitoring site for PM10, in order to gain a comparative result and to
determine the level of RD and RCS in area on the day of sampling. The skylight in the mobile
laboratory was adapted to fit a spike for the sampling head (Figure 4). A 2 m air tube then
linked the sampling head with the pump below. Information about the temperature, pressure,
humidity and prevailing wind direction at the site was obtained with a Davis Vantage pro 2
weather station. At most sites, measurements of the weather conditions were taken every hour.
5
HSL’s
Sampling
inet
PM 10
sampler
inlet
Figure 4 The mobile laboratory with sampler in position next to a local authority PM10
site
6
3
3.1
ANALYSIS STRATEGY
GRAVIMETRIC ANALYSIS FOR RESPIRABLE DUST
The 60 mm mixed cellulose ester (MCE) filters were weighted in a balance room, controlled to
maintain its humidity at 50 ± 5% and its temperature to 20 ± 4°C. The filters were conditioned
in the balance room overnight and weighed on a Mettler balance with a readability of 10 µg.
The non-combustible/volatile fraction of the dust was weighed, after removing the filter by
burning or plasma ashing, on polycarbonate or silver filters, using a Sartorius balance with a
readability of 1 µg.
3.2
RCS ANALYSIS METHOD FOR AMBIENT SAMPLES
Previous work (Mark 2009) describes the development of a method employed for the analysis
of RCS. This analytical method involves the removal of the dust collected on the 60 mm
diameter MCE filter and depositing it onto filters of 25 mm diameter for analysis by X-ray
diffraction (XRD). In this work the calibration and sample preparation procedures described by
the National Institute of Safety and Health in their method 7500 (NIOSH 2003) were adopted.
An EMITECH KIO50X plasma asher was used to remove the air sample filter and the inorganic
dust remaining was filtered onto 0.45 µm pore size polycarbonate filters, to allow the
opportunity of preparing these samples for analysis by scanning electron microscopy (SEM).
3.2.1
XRD instrument specification
The samples were analysed by XRD using the following specifications optimised for intensity
rather than resolution.
• A Panalytical X-pert pro MPD X-ray diffractometer operating with Bragg-Brento semifocusing geometry
• A broad focus tube with copper target operating at 55Kv and 49 mA to give a power
output of 2.7 watts
• Automatic divergence and antiscatter slits set at 18mm
• Spinner set at 1 revolution per second
• Automatic sample changer
• Array detector set on continuous scan mode with a window area of 2.12 degrees.
The 100 reflection at 20.9 degrees 2θ (secondary peak with 25 % intensity), the 101 reflection at
26.6 degrees 2θ (primary peak with 100% intensity) and the tertiary 112 reflection at 50.1
degrees 2θ were calibrated for measurement using Xpert Industry programme and the scan
parameters detailed in Table 3.
7
Table 3: Scan parameters
Angle (2θ)
Scan range
Step size
Counts
per
(seconds)
20.9
19.9 – 21.9
0.05
600
26.6
25.65 – 27.65
0.05
420
50.1
49.1 – 51.1
0.05
600
3.2.2
step
Calibration procedure
Calibration samples were prepared over the analytical range 10 – 500 µg following the
procedure in NIOSH method 7500 (NIOSH 2004). Aliquots from two suspensions, one with 10
mg and one with 50 mg of the HSE quartz standard A9950 in one litre of 2-isopropanol were
filtered onto filters using a Millipore filtration apparatus and a filter funnel with an inner
diameter of 15 mm. This diameter of filter funnel would ensure that all the silica would be
completely within the analysis beam of the instrument. The calibration is shown in Appendix 1.
3.2.3
Sample preparation and recovery tests
The filters were carefully placed into glass bottles which were then put in a plasma asher. The
filters were ashed under air for 12 hours in a plasma generator using a radio frequency (RF)
power setting 49 of and then for 4 hours under oxygen with an RF power setting of 95. A small
amount of 2-isopropanol was then added to the bottle, the bottle was then sealed and ultrasound
for about 5 minutes. The contents of the bottle were then washed onto a onto a 25 mm diameter,
0.4 µm pore size, polycarbonate filter, using the same apparatus involved in the preparation of
the calibration samples. The recovery from the plasma ashing process was determined by
loading 5 filters with 65 µg of the quartz calibration material A9950, using a aliquot of 5 mL
from a suspension of 13 mg of A9950 in 1 litre of 2-isopropanol. The mass of 65 µg was
selected because it was a good challenge as it is a relatively small mass at the lower end of the
range of expected values and the changes in weigh are more significant. The samples were
analysed gravimetrically and by XRD. The manufactures of the plasma ashing apparatus quote a
residue of 0.1 %. The average weight of a filter before ashing was 7.76 mg so the expected
increase in weighs due to residue from the filters is about 7.8 µg. The results of the recovery
tests are shown in Table 4.
Table 4: Recovery Tests
Technique
Filter
1
2
3
4
5
Average
Standard
Deviation
Gravimetric Analysis
Mass (µg) Recovered
(µg)
X-ray Diffraction Analysis
Quartz Result Quartz Result
(µg)
(µg)
Pre ashing
Post ashing
95.17
76.00
74.83
85.67
83.17
82.97
98.00
90.50
89.50
97.00
91.00
93.20
71.40
75.16
69.39
71.98
67.24
65.10
66.18
66.90
71.00
67.28
8.23
3.98
2.93
2.24
8
We were not able to measure two of the samples by XRD before ashing because the filters had
lost their shape (flatness) and obtained slight damage. The average gravimetric results show an
increase in mass, which is only 2µg more than the expected residue from the filters alone
indicating a complete recovery of the sample. The average XRD results show a slight decrease
of 4.7 µg (6.5 %), which slightly statistically significant from the limited data included in the
study (two sided t test probability assuming equal variances p = 0.041), although within the
expected precision of the XRD technique of approximately ± 10 % (1σ) (Stacey et al 2003).
These XRD data indicate an almost complete recovery, which in the worst case is between 89 –
96 % (2σ).
9
4
DESCRIPTION OF CONSTRUCTION SITES AND
RESULTS
4.1
SITE 1: GENERAL CONSTRUCTION ACTIVITIES
4.1.1
Location
The first site involved the construction of offices and class rooms for a college of education a
couple of miles from the centre of a major city in the Yorkshire area. Effectively the college was
being rebuilt whilst the old buildings were still in use, so the distance between work and public
areas was small (<2 m).
4.1.2
Work activities
Work activities observed on the site whilst sampling were, kerb cutting on a couple of occasions
on both days, movement of sand near sampler 1 on the first day for about hour, excavation in
the morning of day 2 and the making of concrete at various times throughout the exercise. The
position of the activities in relation to the samplers is described in the table in 4.1.6. The major
source of potential dust was from the single access road that ran along the back of the site,
which occurred sporadically during the day. The control of traffic movement along this road
was a potential hazard because the route was narrow and allowed little room for traffic to
manoeuvre. Some brick laying was undertaken in the concrete tower block but this was some
distance from the samplers. Pictures of the work activities observed are shown in Appendix 2.
4.1.3
Dust controls
No specific dust controls were observed at the site although few activities generating significant
dust were noticed. The visit to this site occurred before the operational circular SIM 02/2009/01
(HSE, 2008) for controls kerb, pavement and block cutting was released.
4.1.4
Weather
Day 1
Showers started when putting the equipment in place but the ground appeared to dry during the
day. The humidity ranged from 58 – 82 % and the temperature from 7.7 – 15.7 °C. The median
wind direction was from the west (266.50). Unfortunately, wind speed data was not collected at
this site.
Day 2
The day was generally damp with bright spells. There were rain showers in the middle of the
day. The humidity ranged from 53-76 % and the temperature from 8.6 – 12 °C. The median
wind direction was from the west (2680). Unfortunately, wind speed data was not collected at
this site.
10
4.1.5
Location of samplers
Wind Direction For Site 1 Day 2
Wind Direction For Site 1 Day 1
360
340
320
300
20
280
80
260
100
240
220
200
360
40
60
340
320
300
120
140
160
20
40
60
280
80
260
100
240
220
200
180
120
140
160
180
The shaded areas in the charts for wind direction indicate the direction the wind arrives on site. In these charts the samplers labelled 1,2 and 3 are measuring the dust leaving the site. Boundary of work areas are indicated as The plan is orientated so that north is towards the top. 11
4.1.6
Results
Table 5: Results for site 1
Day 1
Tasks
Position
on
the
map
Respirable
Dust
(µg/m3)
Non
combustable
fraction
(µg/m3)
Respirable
Percent RCS
Crystalline
in respirable
Silica
(RCS) fraction
(µg/m3)
1
Adjacent access 28.4
road and nearest
sand movement
10.2
0.22
0.8 %
2
Opposite tower 24.9
block
brick
laying
and
cement mixer
11.4
0.39
1.6 %
3
Outside
gate 19.0
traffic
movements
4.7
0.17
1%
4
In flow from city
17.9
6.5
0.20
1%
Urban
Air
Car park within 5 17.4
–6 m of a busy
road
7.1
0.17
1%
*The PM10 concentration from the TEOM Site in the city centre was 17.2 µg.m-3.
Day 2
Position
Tasks
on
the
map
Respirable
Dust
(µg/m3)
Non
combustable
fraction
(µg/m3)
Respirable
Percent RCS
Crystalline
in respirable
Silica
(RCS) fraction
(µg/m3)
1
Adjacent access 28.9
road for traffic
movement
9.02
0.23
0.8 %
2
Opposite tower 29.5
block and cement
mixer
11.6
0.25
0.8 %
3
Outside gate near 23.3
excavation
7.58
0.13
0.6 %
4b
North of
cutting
6.07
0.08
< 0.1 %
kerb 22.7
12
Urban
Air
Car park within 5 27.7
–6 m of a busy
road
4.69
0.08
< 0.1 %
*The PM10 concentration from a TEOM Site in the city centre was 22.3 µg.m-3
*Result from UK air monitoring network TEOM PM10 site managed by the local authority
(result is not corrected by the compensating factor 1.3). The results from PM10 TEOM samplers
are often multiplied by a factor of 1.3 to make the values comparable with gravimetric analyses.
It is though that some TEOM samplers may under sample PM10.
A single blank sample recorded a residue, after combustion, of 36 µg, which translates to an
potential air concentration of between 1.4 to 1.8 µ/m3 for the mid range of air volumes sampled
(between 20 – 26 m3).
4.2
SITE 2: DEMOLITION
4.2.1
Location
This site involved the demolition of a water tower and boiler house in the grounds of a hospital
with a single JCB excavator. Sampling was focused on this activity.
4.2.2
Work activities
The site was visited over a four-day period. The work activities and their approximate duration
are shown in table 6.
Table 6: Work Activities at Site 2
Day
Activities
Approximate Duration
(hours)
1
No activity – work postponed
2
Excavator removing debris to skip (work stopped due to the
discovery of asbestos lagging)
2
General activities (not potentially dust generating)
5
Some demolition work inside the building
3
Demolition of water tower with excavator with extended arm
8
4
Working to change hydraulic arm on excavator
4
Rubble/pipe movement/ demolition work
3
Photographs of the activities are in Appendix 2. The demolition started in position D and
worked along the building. The water tower was north of position 4.
13
4.2.3
Dust controls
A worker doused falling rubble with water from a hosepipe. Hoses attached to the end of a long
grappling arm of the excavator, supplied from the reservoir of an old fire engine, sprayed top of
the tower with a fine mist of water.
4.2.4
Weather
The following conditions were observed from observations taken every hour of sampling during
the working period.
Day 2:
The day was generally dry and sunny. The average temperature recorded on that day was 18.6
°C and the humidity was 68 %. The wind direction was generally from the southwest, although
the wind speed ranged from 0 to 4 m/s with a median value of 0.4 m/s.
Day 3
The day was cloudy and it rained in the afternoon. The median temperature was 13 °C and the
median humidity was 82 %. The wind was generally from the east with a speed ranging from 0
to 1.3 m/s. The most frequently recorded value for wind speed was zero.
Day 4.
The day was cloudy with some rain in the afternoon. The average temperature was 11 °C and
the median humidity was 69 %. The wind was from the west and its speed ranged from 0 – 5
m/s with a median value of 0.65 m/s.
14
4.2.5
Location of samplers
D
Boundary of work areas are indicated as
The plan is orientated so that north is towards the top
The samplers identified by the circles were used on day 2 and those identified by the squares on
days 3 and 4.
15
4.2.6
Wind Direction
Wind Direction Day 2
360
340
20
320
Wind Direction Day 3
360
340
40
20
320
300
60
40
300
60
280
80
280
80
260
100
260
100
240
240
120
220
220
140
200
120
140
200
160
160
180
180
Wind Direction Day 4
360
340
20
320
40
300
60
280
80
260
100
240
120
220
140
200
160
180
The shaded areas on the wind roses indicate the direction the wind is from.
On day 2 the sampler in position 1 was upwind and the samplers in position 2,3, and 4 were downwind. On day 3 the sampler in position 3 is upwind and sampler 5 is down wind. Sampler 6 is close to
the work activity but slightly upwind. On day 4 the sampler in position 5 is upwind and 3 and 6 are down wind 16
4.2.7
Results
Table 7: Results for site 2
Day 2
Position on Task
the map
Respirable Non
combustable
Dust
fraction
(µg/m3)
(µg/m3)
Respirable
Crystalline
Silica
(RCS)
(µg/m3)
Percent
RCS in
respirable
fraction
1
Up wind sampler
39.0
4.7
0.51
1.3 %
2
South of demolition at the 46.0
fence
6.51
0.63
1.4 %
3
Down wind behind JCB 57.0
demolition area at the
fence
6.38
0.32
0.6 %
4
Near the tower – upwind 39.3
of demolition
8.12
0.18
0.5 %
Urban Air
Car park within 5 –6 m of 34.4
a busy road
5.43
0.23
0.7 %
*The PM10 concentration from a TEOM Site in the city centre was 20.3 µg.m-3
Day 3
Respirable Non
combustable
Dust
fraction
(µg/m3)
(µg/m3)
Position on Task
the map
north
of
Respirable
Crystalline
Silica
(RCS)
(µg/m3)
Percent
RCS in
respirable
fraction
6
Slightly
activity
JCB 30.0
9.74
0.5
1.6 %
5
Down wind behind gates 73.6
west < 10m from tower
33.6
2.25
3%
3
Upwind sampler
24.1
6.4
0.4
1.6 %
Urban Air
Road Background site
33.0
6.11
< 0.32
<1%
*The PM10 concentration from a TEOM Site in the city centre was 18.6 µg.m-3
17
Day 4
Position on Details
the map
Respirable Non
Dust
combustable
fraction
(µg/m3)
(µg/m3)
Respirable
Crystalline
Silica
(RCS)
(µg/m3)
Percent
RCS in
respirable
fraction
3
Down wind sampler
16.2
6.11
0.38
2.3 %
5
Upwind sampler
15.4
1.72
< 0.3
<2%
6
Near fence north
demolition area
of 15.4
3.29
< 0.3
<2%
Urban Air
Road Background site
11.6
4.0
< 0.3
< 2.6 %
*The PM10 concentration from a TEOM Site in the city centre was 12.6 µg.m-3
+ Very windy day at the TEOM site but sheltered by trees at the demolition site
*Results from TEOM PM10 site managed by the local authority (result is not corrected by the
compensating factor 1.3). The results from PM10 TEOM samplers are often multiplied by a
factor of 1.3 to make the values comparable with gravimetric analyses. It is though that some
TEOM samplers may under sample PM10.
4.3
SITE 3: CITY CENTRE RING ROAD CONSTRUCTION
4.3.1
Location
The construction of a road bypass (dual carriage way) in the centre of a major city in the
Midlands.
4.3.2
Activities
Sampling took place on two separate days about a month apart. The activities sampled involved,
hand demolition and recovery of Victorian bricks, excavation, laying of hard core containing
recycled concrete, compressing of hard core with rollers, drilling of concrete, and movement of
lorries along hard core road. These activities took place continuously, except of the drilling of
concrete, which took place for a very short period on the second day. Some kerb cutting took
place on site but not on the days when the visits took place. We were informed that the kerbs
were laid in a way to minimise their cutting and that this activity was sporadic. Cutting activities
were more likely to take place on corners where the blocks required shortening.
Photographs of the activities are in Appendix 2.
4.3.3
Dust controls
There was little evidence of the suppression of dust on site, although it had rained the night
before and the presence of wet areas along the hard-core roadway suggested some water
damping had occurred. The tires of vehicles were not wetted before entering or leaving the site.
Public roads in the vicinity of the site were periodically cleaned with a road sweeper.
18
4.3.3.1
Personal protective equipment (PPE)
The workers wore safety shoes, hard hats, high visibility jackets, and were provided with safety
glasses. Drilling of concrete or brick took place for a short period on day 2. The employee
operating the power drill did not wear a dust mask.
4.3.4
Weather
Day 1:
The weather was generally fine with occasional rain in the afternoon. The median temperature
was 13.4 °C and the median humidity was 75 %. The wind was from the southeast and its speed
ranged from 0 to 2.2 m/s with a median of 1.3 m/s.
Day 2:
The weather station failed during this trip so no specific information is available. There was
some light rain during the day.
4.3.5
Location of samplers
Approximate site boundary is marked as
The plan is orientated so the top is towards north.
The positions identified by the circles were used on day 1 and the positions identified by the
squares were used on day 2.
19
4.3.6
Wind Direction
The following wind direction was observed at the site on day 1.
Wind Direction Day 1
360
340
320
300
20
40
60
280
80
260
100
240
220
200
120
140
160
180
The shaded area indicate the direction the wind is from
The wind direction was along the road on day 1. Trucks carrying hard core entered the site close
to position 1 and spread their loads between sampler positions 2 and 5. Sampler 5 was upwind
of the activity. Sampler 3 was relatively close to a hand demolition activity no upwind sampler
was available for this activity.
20
4.3.7
Results
Table 8: Results from site 3
Day 1
Details
Position
on
the
map
Respirable
Dust
(µg/m3)
(Dots)
Non
combustable
fraction
(µg/m3)
Respirable
Crystalline
Silica (RCS)
(µg/m3)
Percent
RCS
in
respirable
fraction
1
Entrance
where 25.0
lorries enter site
12.7
0.64
2.6
2
Down wind of 35.3
lorries unloading
along hard core
road
16.5
0.72
2.0
3
Down wind of 38.5
hand
demolition
and brick cleaning
18.7
0.11
0.2
5
Down wind of 28.8
brick sorting and
cleaning (< 3m)
12.5
0.69
2.3
Urban Air
Background
6.6
0.44
1.6
27.0
*The PM10 concentration from a TEOM Site in the city centre was 15.4 µg.m-3
Day 2
Position
Details
on
the
map
Respirable
Dust
(µg/m3)
(Squares)
Non
combustable
fraction
(µg/m3)
Respirable
Crystalline
Silica (RCS)
(µg/m3)
Percent
RCS
in
respirable
fraction
1
Down wind of 29.0
tarmac and lorry
unloading
11.1
0.54
1.9
2
Close to fence near 24.0
road
3.8
0.13
0.5
3
Nr
Mosque 41.0
downwind
of
momentary drilling
activity
and
movement
of
lorries
21.3
0.94
2.3
21
4
Urban Air
End
of
site 32.0
opposite occasional
lorry movements
16.9
1.04
3.2
Sampler
failed
*The PM10 concentration from a TEOM Site in the city centre was 16.8 µg.m-3
*The results are from a TEOM PM10 site managed by the local authority and are not corrected
by the compensating factor 1.3. The results from PM10 TEOM samplers are often multiplied by
a factor of 1.3 to make the values comparable with gravimetric analyses. It is thought hat some
TEOM samplers may under sample PM10.
22
4.4
SITE 4: STREET BLOCK CUTTING
4.4.1
Location
The front garden of a house in a residential area.
4.4.2
Activities
Sampling took place on a single day. The work involved laying of blocks on the front garden of
a house in order to provide an area for a vehicle to park involving the excavation of the garden,
laying of sand (a couple of hours in the morning) and other material to level the work area,
cutting of the blocks with cut-off saws (several hours) and laying them.
Photographs of the activities are shown in Appendix 2.
4.4.3
Dust Controls
A container with water, pressurised by periodically pumping a handle, was connected to the disc
saw, wetted the cutting blade. There was no indication on the water container to inform the
worker that the pressure had dropped. It is suspected that the flow rate is inconsistent because of
the occasional reduction of water pressure and the requirement for a worker to pump the
container. This control was unlikely to meet the flow rates specified in A Thorpe et al (1999) for
effective suppression of dust. A bench saw was also used and had a reservoir of water under the
bench work surface to wet the blade.
4.4.4
Personal Protective Equipment
The workers wore, safety helmets, safety boots, high visibility jackets, goggles when cutting the
blocks and gloves when handling the bench saw. None of the workers wore dust masks.
4.4.5
Weather
Weather station was not available so specific data was not obtained. The day was dry and
sunny.
23
4.4.6
Location of samplers
The plan is orientated so the top is towards north
The prevailing wind is usually from the west. The majority of the activity was between samplers
1 and 2. The cutting activity was about 3 - 4 meters west and other activity took place in the
garden of a house 5 – 6 meters east of samplers 1 and 2.
24
4.4.7
Results
Table 9: Results from site 4
Position
Details
Respirable
Dust
(µg/m3)
Non
combustable
fraction
(µg/m3)
Respirable
Crystalline
Silica (RCS)
(µg/m3)
Percent
RCS
in
respirable
fraction
1
Nr Driveway 73.4
and
gate
opposite
cutting bench
58.9
11.1
15
2
Opposite side 76.9
of gate near
near cutting
saw area
53.65
11.9
15
3
About 10 m 27.8
from sampler
2
12.8
2.9
10
13.0
3.61
Urban Air
*The PM10 concentration from a TEOM Site in the city centre was 14.3 µg.m-3
*The results are from a TEOM PM10 site managed by the local authority and are not corrected
by the compensating factor 1.3. The results from PM10 TEOM samplers are often multiplied by
a factor of 1.3 to make the values comparable with gravimetric analyses. It is thought hat some
TEOM samplers may under sample PM10
4.5
SITE 5: STREET BLOCK CUTTING
4.5.1
Location
Area of road allocated for on street parking by residents in a suburb of a city in Yorkshire.
4.5.2
Activities
Sampling took place on a single day. This work involved the packing of sand and levelling the
area designed to contain the block cutting. Placing blocks in the allocated pattern, cutting blocks
with a disc cutter to fill in the remaining spaces and packing sand.
4.5.3
Dust controls
A pressurised water container was attached to the disc cutter. I was informed that the pattern of
blocks was purposefully designed to reduce the amount of cutting. The maximum cutting time
was about 40 minutes in a working day of about 6 hours.
4.5.3.1
Personal protected equipment (PPE)
The workers wore, safety helmets (although not all the time), safety boots, high and visibility
jackets. None of the workers wore dust masks.
25
4.5.4
Weather
The weather was warm and dry with little wind. The median temperature was 19 °C and the
median humidity was 59 %. The wind was from the north, directly down the street, and had a
speed between 0.1 to 0.2 m/s (median wind speed was 0.1 m/s).
4.5.5
Location of samplers
Wind Direction During Cutting
360
20
340
320
40
300
60
280
80
260
100
240
120
220
140
200
160
180
The plan is orientated so the top is towards north
The shaded area on the wind rose indicates the direction the wind is from.
Sampler 1 was moved to position 1b after a couple of hours as it was clear that no activity was
taking place near its location.
26
4.5.6
Results
Table 10: Results from site 5
Position
Details
Respirable
Dust
(µg/m3)
Non
combustable
fraction
(µg/m3)
Respirable
Crystalline
Silica (RCS)
(µg/m3)
Percent
RCS
in
respirable
fraction
1/1b
Middle of site 35.1
near sand and
cutting area
10.1
1.20
3.4
2
Upwind
of 25.5
cutting area
9.6
1.06
4.1
3
Down wind 35.5
of
cutting
area
6.2
0.5
1.4
17.5
2.8
0.16
1.0
Urban Air
*The PM10 concentration from a TEOM Site in the city centre was 19.0 µg.m-3
*The results are from a TEOM PM10 site managed by the local authority and are not corrected
by the compensating factor 1.3. The results from PM10 TEOM samplers are often multiplied by
a factor of 1.3 to make the values comparable with gravimetric analyses. It is thought hat some
TEOM samplers may under sample PM10
4.6
SITE 6: RUBBLE CLEARANCE FROM DEMOLITION
4.6.1
Location
The site of a demolition of a 3 level block of flats in a residential area, with 3 miles of a city
centre.
4.6.2
Activities
Sampling took place on a single day. The workers used a JCB to move brick and concrete
rubble into piles and to load into trucks. The work progressed
Photographs of the activities are shown in Appendix 2.
4.6.3
Dust Controls
A worker with a hosepipe dosed the rubble and contents of lorries with water.
4.6.3.1
Personal protected equipment (PPE)
The workers wore, safety helmets, safety boots, high and visibility jackets. None of the workers
wore dust masks.
27
4.6.4
Weather
The day was warm but cloudy and the ground was initially damp from rain the previous night.
The median temperature was 21 °C and the median humidity was 73 %. The recorded wind
direction was from the northeast with a speed between 0.1 to 1.3 m/s (median wind speed was
0.7 m/s).
4.6.5
Sampler Locations
Wind Direction
360
340
320
300
20
40
60
280
80
260
100
240
220
200
120
140
160
180
Approximate boundary is shown as
The plan is orientated so the top is towards north
The shaded area on the wind rose indicates the direction the wind is from.
28
4.6.6
Results
Table 11: Results from site 6
Position
on map
Details
Respirable
Dust
(µg/m3)
Non
combustable
fraction
(µg/m3)
Respirable
Percent RCS
Crystalline
in respirable
Silica (RCS) fraction
(µg/m3)
1
Nearest
opposite
movement
JCB
road 25.8
rubble
with
5.2
Not Detected
2
Parameter opposite 18.1
cabin
5.6
0.41
2.2
3
Top of site near 35.3
JCB
rubble
movement during
the afternoon
25.2
1.31
3.7
4
Adjacent to skip 42.0
and
placed
in
direction of drifting
dust from loading
lorries
29.3
1.17
4.0
3.6
0.25
2.0
Urban
Air
11.9
*The PM10 concentration from a TEOM Site in the city centre was 12.7 µg.m-3
*The results are from a TEOM PM10 site managed by the local authority and are not corrected
by the compensating factor 1.3. The results from PM10 TEOM samplers are often multiplied by
a factor of 1.3 to make the values comparable with gravimetric analyses. It is thought hat some
TEOM samplers may under sample PM10
The direction of the wind recorded by the weather station would indicate that samplers 1 and 2
were down wind and samplers in positions 3 and 4 were upwind. However, these recordings are
contrary to observations on the day of sampling, which suggested that the wind was actually in
the opposite direction. It is highly possible that a problem occurred with the weather station’s
wind vane that wasn’t detected on the day, since the predominant wind direction recorded by
several airports in the same region was from the west and the site was exposed towards the west
whereas the north and east had some tree cover. The sampling positions that obtained the
highest values were on the northeast parameter behind which were grass fields, so the potential
source for the dust levels supposedly entering the site is not obvious.
29
4.7
SITE 7: DEMOLITION OF COLLEGE
4.7.1
Location
The site was situated near the centre of the city near, high street shopping areas, offices and a
court.
4.7.2
Activities
The sampling was performed on two days about a week apart. The work activities observed
were; the breaking up of concrete with powered hammers attached to excavators (all day on the
first day); removal of walls and material with an extended arm on an excavator and movement
of vehicles sorting of concrete and brick rubble (both days).
Photographs of the activities are shown in Appendix 2.
4.7.3
Dust Controls
A pump linked to a mobile container (trailer size) would project a jet of water towards the area
under demolition (four floors high).
4.7.3.1
Personal protected equipment (PPE)
The workers wore, safety helmets, safety boots, high and visibility jackets. None of the workers
wore dust masks.
4.7.4
Weather
Day 1:
The weather was cloudy but dry. The median temperature was 15 °C and the median humidity
was 66 %. The wind was mainly from the west with a wind speed between 0.4 to 1.8 m/s
(median wind speed was 0.4 m/s).
Day 2
The weather was cloudy with some rain in the afternoon. The median temperature was 17.7 °C
and the median humidity was 70 %. The wind was from the northwest with a wind speed
between 1.8 to 2.7 m/s (the median wind speed was 2.2 m/s).
30
4.7.5
Location of Samplers
Weather Day 1
360
340
20
40
320
300
60
280
80
260
100
240
120
220
140
200
160
180
Weather Day 2
360
340
320
300
20
280
80
260
Approximate site boundary is indicated as
The purple square marked with the arrow in the building represents
the approximate site of work with the JCB extended arm
100
240
220
200
120
140
160
180
The chequered boxes represent previously demolished buildings. Movement of rubble and
drilling of concrete with JCBs took place in the chequered box above the area marked by the
arrow.
The shaded areas in the wind roses represent the direction the wind is from.
The positions identified by the circles were used on day 1 and the positions identified by the
squares were used in day 2.
The sampler in position 1 (circle) was upwind on day 1 and samplers 2,3 and 4 (circles) were
down wind. On day 2, none of the samplers (boxes) were in an ideal position to be classified as
the upwind sampler. However, the sampler in position 4 (box) is the most upwind sampler and
sampler positions 1,2 and 3 (boxes) are downwind.
31
40
60
4.7.6
Results
Table 12: Results from site 7
Day 1
Position
on map
Details
(µg/m3)
Non
combustable
fraction
(µg/m3)
Respirable
Crystalline
Silica
(RCS)
(µg/m3)
Percent
RCS in
respirable
fraction
25.3
10.5
0.7
2.7
Respirable
Dust
(Spots)
1
Upwind sampler
2
Down wind
hammer drills
JCB 51.4
37.7
8.36
16
3
Down wind of demolition 85.0
with extended arm
44.1
11.5
14
4
Near rest areas and in dust 184
from demolition
145.3
7.65
4.1
12.6
0.29
1.5
Urban
Air
of
18.8
*The PM10 concentration from a TEOM Site in the city centre was 18.9 µg.m-3
Day 2
Position
on map
(Squares)
Details
Respirable
Dust
(µg/m3)
Non
combustable
fraction
(µg/m3)
Respirable
Crystalline
Silica
(RCS)
(µg/m3)
Percent
RCS in
respirable
fraction
1
Down wind of JCB 229.3
demolition with extended
arm
185.9
11.2
5
2
Further down wind from 1 143.9
near
College
Road
Entrance
110.5
9.9
7
3
Down wind of demolition 90.5
near the rest area
58.5
8.1
9
4
Opposite Portacabin and 43.5
rubble movement
28.3
7.4
17
4.2
0.25
1.5
Urban
Air
16.0
32
*The PM10 concentration from a TEOM Site in the city centre was 13.5 µg.m-3
*The results are from a TEOM PM10 site managed by the local authority and are not corrected
by the compensating factor 1.3. The results from PM10 TEOM samplers are often multiplied by
a factor of 1.3 to make the values comparable with gravimetric analyses. It is thought hat some
TEOM samplers may under sample PM10
33
5
COMPARISON WITH TEOM MEASUREMENTS
HSL Respirable dust concentration µg/m3
Background measurements, from the centre of the town or city were compared with data
provided by the local authority, from air quality monitoring sites for PM 10 measurements taken
over the same sampling period in approximately the same area. The HSL sampler was often
located next to the local air quality-monitoring site to provide a direct comparison, however co­
location of samplers was not always possible, or the Tapered Element Oscillating Microbalance
(TEOM) instrument operated by the local authority failed, obtained negative values or had a
scheduled service. Figure 5 compares the gravimetric result obtained from the HSL sampler
working to the occupational hygiene convention for respirable dust with the result obtained with
the TEOM analyzer, working to the PM10 convention used in environmental science, operated
by the local authority or UK national air quality monitoring site. When compared with the
European Union reference samplers TEOM results are multiplied by a factor of 1.3 to
compensate for some under sampling. However, the results shown in Figure 5 are not corrected
using this factor because the uncorrected results provided the best visual correlation with the
line drawn on the chart for the ideal 1:1 relationship.
40
35
30
25
20
15
Linear (1:1
Relationship)
10
5
0
0
5
10
15
20
25
30
35
40
TEOM PM10concentration µg/m3
Figure 5 Comparison with TEOM results (uncorrected)
The majority of results are close to the ideal 1:1 relationship. The following observations were
made for the four samples where the result from the HSL sampler was higher than the TEOM
result.
• The HSL sampler was parked much closer to the road (< 10 m) compared with the local
authority site (approximately 20 – 30m)
• It was windy and at TEOM site, which actually recorded some negative values,
suggesting a leak, a high concentration of volatile particles or other problems.
• The TEOM was serviced that day and the measurement supplied by the local authority
might not be representative of the area in which the HSL sample was taken.
The good correlation is probably because the particle sizes of the most likely major components
of urban air dust (diesel fume, pollen and organic volatiles) are very small, so the different size
selection parameters do not significantly influence the mass collected on the filter.
34
6
CRYSTALLINE COMPONENTS OF URBAN AIR
The air sample filters were scanned by XRD using a 25 mm diameter filter holder and a low
background silicon substrate as a backing material. The use of X-ray diffraction allows the
identification of the crystalline components of the dust and the following substances were found
(Table 13). Some filters were scanned in sampler holders designed at HSL to suspend the filter
by its edges. The samples locations identified as ‘urban air’ were taken by a sampler sited some
distance from the work area to provide an indication of the background levels and type of dust
at a location way from the construction activity.
Table 13;Proposed crystalline components in the analysis samples
Site
Location
City 1 Site 1 Urban
Day 1
Air
(October)
Proposed Crystalline Components
Quartz (SiO2), Calcite (CaCO3), Anhydrite (CaSO4)
Probable Halite (NaCl) or Chlorargyrite (AgCl)
Possible Diiron di-calcium oxide Fe2O3(CaO)2, and Iron Nitride
(Fe4N)
On Site
Quartz (SiO2), Calcite (CaCO3),
City 1 Site 1 Urban
Day 2
Air
Quartz (SiO2), Calcite (CaCO3), Halite (NaCl), Kaolinite (clay)
possibly Iron (Fe)
(October)
Quartz (SiO2), Calcite (CaCO3), possibly Maganosite MnO,
Anatase (TiO2) and Maghemite (Fe2O3), or Tin Sulphide (SnS), or
Na4 (SO4)1.5(CO3)0.5, or PbSnS2
On site
City 2 Site 2 Urban
Day 2
Air
(April)
On site
City 2 Site 2 Urban
Day 3
Air
(May)
On site
Quartz (SiO2), Calcite (CaCO3), Halite (NaCl),
Ferrite (Fe) or Aluminium (Al) contamination from sample
preparation process
Quartz (SiO2), Calcite (CaCO3), Halite (NaCl), possibly a Mica
(Muscovite)
Quartz (SiO2), Calcite (CaCO3), Halite (NaCl), Ferrite (Fe) or
Aluminium (Al) contamination from sample preparation process,
Illite (clay) K(H2O) Al2Si3AlO10(OH)2, Tobermorite 9 A
Ca5(Si6O16)(OH)2 or Kaolinite (clay), Dolomite CaMg(CO3)2
Quartz (SiO2), Calcite (CaCO3), Maghemite (Fe2O3), Tricalcium
silicate and probably a clay or mica
City 2 Site 2 Urban
Day 4
Air
Quartz (SiO2), Calcite (CaCO3), Calcium Sulphate Hydrate
(CaSO4)0.15 H2O
(May)
Quartz (SiO2) and possibly Halite NaCl
On site
35
City 3 Site 3 Urban
Day 1
Air
(May)
On site
Halite (NaCl), Quartz (SiO2), Calcite (CaCO3),
Ferrite (Fe) or Aluminium (Al) contamination from sample
preparation process
Quartz (SiO2), Calcite (CaCO3) or (MgCaCO3), Maghemite (Fe2O3),
Halite (NaCl), Kaolinite (Al2(Si2O5)(OH)4)
City 3 Site 3 Urban
Day 2
Air
Halite (NaCl), Quartz (SiO2), Calcite (CaCO3),
(July)
Quartz (SiO2), Calcite (CaCO3) or (MgCaCO3), Maghemite (Fe2O3),
Halite (NaCl), Kaolinite (Al2(Si2O5)(OH)4), possibly Illite (clay)
and Tricalcium silicate (concrete or cement product).
On site
City 4 Site 4, Urban
Day 1
Air
Quartz (SiO2), Calcite (CaCO3), Ferric Oxide (Fe2O3), possibly Iron
Fe
(July)
Quartz (SiO2), Calcite (CaCO3) or (MgCaCO3), Halite (NaCl),
Kaolinite (Al2(Si2O5)(OH)4), possibly Illite (clay).
On site
City 2, Site 5, Urban
Day 1
Air
Halite (NaCl), Quartz (SiO2), Calcite (CaCO3), Maghemite (Fe2O3),
(September)
Quartz (SiO2), Calcite (CaCO3) or (MgCaCO3), Halite (NaCl),
Kaolinite (Al2(Si2O5)(OH)4), Anhydrite (CaSO4)
On site
City 2 Site 6, Urban
Day 1
Air
Halite (NaCl), Quartz (SiO2), Calcite (CaCO3), Maghemite (Fe2O3),
Kaolinite (clay)
(September)
Quartz (SiO2), Calcite (CaCO3), Anhydrite (CaSO4), Calcium
Silicate Hydrate (CaSO4)0.5 H2O, possibly Dicalciumsilicate
Ca2(SiO4)
On site
City 2, Site 6 Urban
Day 2
Air
Halite (NaCl), Quartz (SiO2), Calcite (CaCO3),
(September)
On site
Quartz (SiO2), Calcite (CaCO3), Halite (NaCl), Calcium Silicate
Hydrate (CaSO4)0.5 H2O, Portlandite (Ca(OH)2) probably Hatrurite
(Ca(SiO4)O)
City 1Site 7
Urban
Air
Halite (NaCl), Quartz (SiO2), Calcite (CaCO3), Iron Sulphite FeS or
Maghemite (Fe2O3), possibly Ferrite Fe or Al
On site
Quartz (SiO2), Calcite (CaCO3), Halite (NaCl), Anhydrite (CaSO4)
Calcium Silicate Hydrate (CaSO4)0.5 H2O, Dolomite
(CaMg(CO3)2) possibly (Fe4N)
Day 1
(August)
XRD reflections highly indicative of the presence of halite (NaCl), were found in most of the
urban samples, except for those in July and for the first set of results, when silver filters were
used in the preparation of the analysis filters. The scans of the dust on the silver filters indicate
the presence of chlorargyrite (AgCl), rather than NaCl, which is possibly due to a reaction
between NaCl, the silver filter and the isopropanol used to recover the dust from the air sample
36
filter. June was a particularly dry month in 2009 and the sampling took place in the early in
July. It is postulated that the absence of salt in the urban air is dependent on dry periods of
weather because the highly soluble salt is probably incorporated in the moisture or water
vapour. XRD reflections indicative of anhydrite (CaSO4) and calcium sulphate demihydrate
(CaSO40.5H2O) rather than gypsum (CaSO42H2O), were found on many of the samples. This is
possibly due to a reaction between gypsum and heat, even though the majority of samples were
ashed in a low temperature plasma asher rather than a furnace. Many of the urban air samples
showed only the presence of the primary calcite or quartz reflection. In these cases, it was
assumed that quartz and calcite were present because of the confirmatory evidence of secondary
reflections in other scans form other urban air samples. Calcium silicates associated with
concrete or cement, calcium hydroxides, and iron oxides are indicative of industrial activity.
Calcium sulphates are likely to be indicative of domestic and industrial activity since there were
no natural deposits in the vicinity of the cities where the sampling activity took place. Calcite
and quartz are minerals that are both naturally present in the geology of the location of several
of the cities visited and also components of building work. Many of the samples of dust
recovered from the ashing process were pink or orange, which may confirm the presence of
hematite or iron converted to hematite. Figure 5 shows the colours of some of the samples.
Sample 08830/08 shown in the picture is a field blank sample.
Figure 6 Colour of samples after recovery
The presence of quartz, gypsum, clays, halite and calcite in environmental type samples are
confirmed in other work from Spain (Bernabé et al, 2005)
37
7
7.1
DISCUSSION
SUMMARY OF RESULTS
Presented in the table 14 is a summary of the results obtained from the sampling of construction
sites
Table 14: Summary of dust results
Respirable Dust (ISO/CEN Convention)
Value
Urban
Air
General
Activities
Road
Building
Block
Cutting
Demolition
Median µg.m-3
17.5
24
29
35.1
40.6
Minimum µg.m-3
11.6
17.4
24
17.5
15.4
Maximun µg.m-3
34.4
29.5
41
76.9
229
9
10
7
22
Number
Samples
of 11
Non conbustable and non volatile respirable dust
Value
Urban
Air
General
Activities
Road
Building
Block
Cutting
Demolition
Median µg.m-3
4.7
7.3
12.7
10.1
10.1
Minimum µg.m-3
2.8
4.7
3.8
2.8
1.7
Maximun µg.m-3
12.6
11.6
21.3
58.9
186
9
10
7
22
Block
Cutting
Demolition
Number
Samples
of 11
Respirable Crystalline Silica
Value
Urban
Air
General
Activities
Road
Building
(TWA)*
(TWA)*
Median µg.m-3
0.24
0.19
0.64
1.2 (1.8)
0.94 (2.1)
Minimum µg.m-3
0.08
0.08
0.11
0.16 (0.33)
0 (0.31)
Maximun µg.m-3
0.44
0.39
1.04
11.9 (12.8)
11.5 (13.5)
9
10
7
22
Number
Samples
of 8
38
(TWA)* is the 8-hour time weighted average without breaks
The majority of values reported in table 14 are close to the results for 8-hour time weighted
averages (TWAs) because the sampling took place continuously over the working full shift.
7.2
RESPIRABLE DUST
The median values for respirable dust were found to increase in the following order,
Demolition Activities
Block cutting
Road Building
Increasing
median
respirable dust value
General Construction Activities
Urban Air
The order of these activities may also be dependent on the environmental conditions at the
location and not just the type of activity.
The distribution of results for respirable dust are shown in Figure 7
25
Demolition
Block Cutting
Road Building
General Activities
Urban air
Frequency
20
15
10
5
10
20
30
40
50
60
70
80
90
10
0
11
0
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
21
0
0
-3
Respirable Dust Levels (µg/m )
Figure 7 Respirable Dust Levels
Figure 7 shows that most results in this pilot study are unlikely to be significantly different from
the range of values obtained for urban air. The Shapiro-Wilk normality test indicated that only
the distribution of results from the demolition activity were not normally different at the 95 %
confidence level (p = < 0.001). In the United Kingdom it is a requirement in the Air Quality
Standards regulations (Crown 2002, 2007) that a daily exposure for PM10 over 24 hours should
39
not exceed 50 µg.m-3 more than 35 times (7 times in Scotland) a year. The annual mean is
required to be below 40 µg.m-3. No results from the general construction activities and the urban
air sites were above 40 µg.m-3. Only the block cutting and demolition activities gave results
above 50 µg.m-3. Two results from samplers sited very close to the block cutting work and 8 out
of 22 results from the demolition activities were above the UK air quality value for PM10. Most
of these results came from the very largest demolition activity where control of dust was
difficult because of the size of the building. Some of the samplers at the demolition site were
well inside the parameter but at a distance from the site of the major work activity (~50 m). It
was fortuitous that the majority of the site was down wind of the demolition activity and the
samplers could be accommodated within the perimeter. On the eastern side, < 20 m from the
demolition, was the local crown court.
7.3
WEIGHT OF DUST RECOVERED FROM ASHING
A low temperature plasma asher was selected to remove the air sample filter in the analytical
recovery process, rather than a furnace, because the plasma asher is able to effectively remove
the carbon particulate and is less likely to cause chemical changes in the mineral components
present. However, results from the XRD diffraction scans suggest that gypsum was altered to
the demi hydrate or anhydrate form. This may slightly affect the weights obtained from the
recoveries. Table 15 shows the average combustible and volatile content in the sample from
each sector studied (not blank corrected).
Table 15: Average combustible and volatile matter (percent)
Activity
Average Value (%)
Demolition
42
Block Cutting
47
Road Building
57
General Activities
67
Urban Air
73
Decreasing
combustible/
volatile
content
in
the samples
These results suggest that the majority of the mass collected by the samplers by three of the
activities (urban air background measurement, general construction activities and road building)
originated from carbon-based substances. Harrison (2000) predicts that the composition of the
origin of urban air samples would be 47 % from combustion sources and 32 % from secondary
sources. In the urban air samples 73 % of the dust by mass on average is probably from vehicle
emissions or pollen and about 27 % is probably dust from the local geology, industrial and road
safety activities (salting). The value of 73 % in this report is close to the combined primary
combustion and secondary particles estimate.
7.4
RESPIRABLE CRYSTALLINE SILICA
The results for RCS in the dust were low for all the activities (< 13 µg.m-3). The presence of the
secondary quartz peaks in the XRD scans for the urban air samples was only observed on a
couple of the scans, so the quantification is based on the primary XRD reflection at 26.67
degrees 2θ, and assuming no other interference is present at this angle. At one point all the
results had to be reanalysed because a peak at 26.67 was found to originate from an aluminium
40
backing plate in the filter holders supplied by the manufacturer. Thirty six percent of samples
(16 from 44 filters) from the sites reported values greater than or equal to 1 µg.m-3 (a 1/100th of
the present WEL of 100 µg/m3). There were four peak exposures that were greater than 10
µg.m-3 (1/10 of the current WEL), two from the block cutting and two from the demolition. The
two samplers from the block cutting with results greater than 10 µg.m-3 were sited close to the
cutting activity (approximately < 5 m) because work activity area was small (a front garden and
pavement) and data from the demolition activities are skewed because site 7 obtained the
majority of results (7 out of 8) close to or above to 10 µg/m3 (7.5 – 13.5 mg.m-3).
7.5
TRANSPORT OF DUST ACROSS THE SITES
Table 16 compares the differences between the upwind and down wind air concentration values
for respirable dust. The results obtained for the sampler sited to determine a general level of
dust not influenced by the site, termed the ‘urban s air’, also shown for comparison is ascertain
if the results for the upwind samples were influenced by the work activity. The average of the
upwind measurements is not significantly different from the average value from the urban air
background samples (p=0.2). All the activities show a positive increase for respirable dust when
compared with the value obtained for the upwind air concentration, except one. The exception
was from a demolition site where the main activity was to change the grappling arm on a
machine. This work was not likely to produce measurable levels of dust, although, some
activities such as, the movement and sorting of rubble and demolition, took place for about three
hours in the afternoon. The highest levels are from block cutting (maximum ratio of upwind air
concentration to average down wind air concentration = 2.7) and demolition (maximum ratio of
upwind will be higher because for block cutting and the demolition at site 7 the proximity of the
upwind sampler to the work activity is likely to have influenced results.
41
Table 16: Transport of respirable dust across the sites
Site
Activity
Ratio
(UA) µg.m-3
Down Wind
Average
(DW)
µg.m-3
Upwind
result
Urban
result
(UP) µg.m-3
air
(DW/UP)
1
General
17.9
17.4
24.1
1.3
1
General
22.7
27.7
27.3
1.2
2
Demolition
24.1
33.0
50
2.1
2
Demolition
15.4
11.6
15.8
1.0
3
Road
28.8
Construction
27.0
36.9
1.3
3*
Road
24
Construction
Failed
34
1.4
4
Block
cutting
27.8x
13.0
75.2
2.7
5
Block
Cutting
25.5
17.5
35.3
1.4
6
Rubble
Moving/Sort
ing
23.0#
11.9
38.7
1.7
7
Demolition
23.3
18.8
107
4.6
7
Demolition
43.5X
16.0
154
3.6
* Assuming the lowest value is down wind
X
Upwind sampler is possibly sited too close to the activity
#
Average of two values
Table 17 compares the differences between upwind and downwind air concentrations of RCS.
These results indicate that, generally, RCS does migrate across the site boundaries and
potentially into public areas, although the air concentrations are low. Nine of eleven values are
positive and two others are negative suggesting that RCS was moving onto site or not
significantly different from the air concentration generated by the activity. Surprisingly, one of
these ratios is from a block cutting activity which may indicate the sampler was either too close
to the activity or that was influenced by other dust from activities further up the street. A ratio
less than 1 was also obtained from the road construction activity. A relatively high value for the
upwind sampler at site 7 (7.4 µg/m3) and at site 4 (2.9 µg/m3) indicate the samplers were
probably sited too close to work activity. The air concentration values obtained from ‘urban air’
samples ranged from not detected to 0.44 µg/m3. Five of the values from the upwind sites were
42
over 0.44 µg/m3, which may indicate the samplers were too close but the higher levels could
also be due to the environmental conditions at the site.
Table: 17; Transport of RCS across construction sites
Site
Activity
Upwind result
(UP) µg.m-3
Down
Average
µg.m-3
Wind Ratio
(DW)
(DW/UP)
1
General
0.2
0.26
1.3
1
General
0.08
0.2
2.5
2
Demolition
0.4
1.4
3.4
2
Demolition
<0.3
0.38 (max)
1.3 (maximum value)
3
Road
Construction
0.69
0.49
0.7
3*
Road
Construction
0.13
0.84
6.4
4
Block cutting
2.9X
11.5
4.0
5
Block Cutting
1.1X
0.85
0.8
6
Rubble
<0.3
Moving/Sorting
0.96
>3.2
7
Demolition
0.7X
9.17
13
7
Demolition
7.4X
9.7
1.3
* Assuming the lowest value is down wind
X
Upwind sampler is possibly sited too close to the activity
43
8
CONCLUSIONS
The following conclusions were observed from these data.
The HSL sampler provides a good indication of both occupational and environmental air
concentrations because the air concentrations for respirable dust obtained by sampler developed
at HSL correspond closely to the PM10 results obtained by the local authority TEOM samplers
(uncorrected by 1.3). The regression coefficient (r2) excluding extreme values was 0.92.
All sites visited were trying to apply what they perceived as reasonable controls for health and
safety. Although, even in dusty areas, most workers did not wear masks.
The results obtained for respirable dust are generally low. Nine out of forty four results (20%) at
construction sites were above the United Kingdom’s air quality standard value for PM10 of 50
µg.m-3. Two of the results > 50 µg.m-3 were from samplers sited within close proximity (< 5
m) to block cutting and the rest of the results > 50 µg.m-3 were attributable to demolition
activities.
On average the residue remaining from the plasma ashing of the air samples from different
construction activities constituted between 58 - 27 % of the sample. The urban air samples lost
73 % of their weight (on average) after ashing. Samples from block cutting or demolition
contained a larger residue (53 – 58%) compared with road building, general activities and urban
air samples (27 – 43 %), suggesting a higher mineral component and therefore associated with
the activities being monitored.
The estimated range of values for RCS from the urban air comparative samplers was
approximately 0.1 – 0.44 µg.m-3. Sixteen samples (36%) from construction sites reported air
concentrations in excess of 1 µg.m-3 and five (11%) were 10 µg.m-3 or above. This proportion is
greater than the study from quarries by Mark et al (2009) who found 4 % of samples with RCS
> 10 µg.m-3, however the current study is not as statistically robust because fewer samplers were
taken.
The ratios of air concentrations of RCS between the upwind and down wind samplers indicate
the migration of silica across sites and potentially beyond the site boundaries.
Many of the mineral components in the samples from the urban air are also found in samples
from construction sites which suggests the origin of the dust is either from the buildings in the
urban environment, the mineralogy of the area or from the construction sites themselves. The
sampling volumes were not sufficient to positively confirm a link.
The results in this pilot study indicate that dust control may still be a problem with very largescale demolition activities and with cut-off saws and that these areas may warrant further
investigation.
44
45
9
REFERENCES
British Standards Institution (1993) Workplace atmospheres - Size fraction definitions for
measurement of airborne particles BS EN 481 1993 ISBN 0 580 22140 7
Bernabé J, M Carretero, Galán E,(2005) Mineralology and origin of atmospheric particles in
the industrial area of Huelva (SW Spain), Atmospheric Environment, 39 p 6777 – 6789, 2005.
Bontempi E et al (2008), Analysis of crystalline phases in airborne particulate matter by twodimensional x-ray diffraction, J. Environ. Monit 10, 82-88
Crown (2002) Office of Public Sector Information Statutory Instrument No. 297 Environmental
Protection The Air Quality (Scotland) Amendment Regulations 2002
http://www.opsi.gov.uk/legislation/scotland/ssi2002/20020297.htm last viewed 29th
March 2010
Crown (2007), Office of Public Sector Information, Statutory Instrument No 64, The Air
Quality Standards Regulations 2007,
http://www.opsi.gov.uk/si/si2007/uksi_20070064_en_1 last viewed 24th June 2010.
Esteve V et al. (1997), Quantitative x-ray diffraction phase analysis of airborne particulate by a
cascade impactor sampler using Riedweld full pattern method. Powder Diffraction , September
1997 Vol12, No3, pp. 151-154
Harrison R (2000), Session 2E – Source apportionment of PMx (Special Session), Studies of the
source apportionment of airborne particulate matter in the United Kingdom, J Aerosol Sci, Vol
31, Suppl 1 pp S106 – S107, 2000
HSE (2009) Health and Safety Executive Operational Circular SIM 02/2009/01 The control of
silica risks associated with kerb, paving an block cutting.
http://www.opsi.gov.uk/si/si2007/uksi_20070064_en_1 last viewed April 2010.
Kenny LC and Lidén G (1991) A technique for assessing size-selective dust samplers using the
APS and polydisperse test aerosols, J. Aerosol Sci., 22, 91-100.
Mark D, Thorpe A,Saunders J, Stacey P and Cottrell S (2009), Assessment of ambient levels of
respirable crystalline silica in quarries, HSL report ECM/2008/12, Health and Safety
Laboratory, Harpur Hill, Buxton, SK17 9JN.
Met Office (2009) Summer 2009 Roundup, Crown Copyright
http://www.metoffice.gov.uk/corporate/pressoffice/2009/pr20090907.html Last viewed in April
2010.
Moore M (1999) Crystalline silica: occurrence and use, Indoor and Built Environment, 8, 82-88.
NIOSH (2003)) 7500 Silica, Crystalline by XRD (filter redeposition) NIOSH Manual of
Analytical Methods NMAM Fourth Edition, Cincinnati Ohio USA
Rice F (2000), Consise International Chemical Assessment Document No 24, Crystalline Silica,
Inter-organizational programme for the sound management of chemicals, International
programme on chemical safety, World Health Organization
Geneva, 2000,
http://www.inchem.org/documents/cicads/cicads/cicad24.htm#PartNumber:5
46
Shiraki R and Holmen BA (2002) Airborne respirable silica near a sand and gravel facility in central California: XRD and elemental analysis to distinguish source and background
quartz.Environ. Sci. Technol, 36, 4956-4961 Stacey P, Tylee B, Bard D, and Atkinson R, (2003) The performance of laboratories analysing α-quartz in the Workplace Analysis Scheme for Proficiency (WASP), Ann occup Hyg, Vol 47, No4, pp 269 – 277, 2003 Thorpe A, Ritchie A, Gibson M and Brown R (1999), Measurements of the effectiveness of Dust Control on Cut-off Saws Used in the Construction Industry, Ann occup Hyg, Vol 43, No7 pp 443-456, 1999
Weather Underground (2010) http://www.wunderground.com/global/UK.html, last viewed
April 2010
Whittaker, A.G. (2003). Jones, T.P, Shao, L-Y., Shi, Z., BéruBé, K.A. and Richards, R.J.
Mineral Dust in Urban Air: Beijing, China. Min. Mag, 67(2), 173-182.
47
10
APPENDICES 1: XRD CALIBRATIONS
Re-deposition of A9950 on Silver Filters
(corrected for crystallinity)
600
Qtz 50 = 19.102x
R 2 = 0.9909
Qtz 26 = 2.2616x
R2 = 0.9965
500
Qtz 21 = 14.418x
R 2 = 0.9902
Mass (µg)
400
QTz21
300
Qtz26
Qtz50
200
100
0
0
50
100
150
200
250
Intensity (cps)
48
11
11.1
APPENDIX 2
SITE 1 CONSTRUCTION Figure 8 Location of sampler in position 3 Figure 9 Location of sampler in position 4
49
Figure 10 Location of sampler for city centre background measurement
Figure 11 On site cement plant opposite sampler 2 50
Figure 12 Excavation activities near sampler positions 2 and 3 on day 2. Sampler 3 is
about 10 m to the right of the excavation.
11.2
SITE 2 DEMOLITION
51
Figure 13 General site and position of sampler 1 on day 2
Figure 14 The demolition site
HSL
sample
position
TEOM PM10 Sampler Site
Figure 15 City centre site with the local authority TEOM PM 10 monitoring site in the
background
52
Figure 16 Activity Day 2
Figure 17 Activity stopped on day 2 due to the discovery of Amosite asbestos pipe
lagging
53
Figure 18 Demolition Activity Day 3
Figure 19 Controls during demolition on day 3
54
11.3
SITE 3: RING ROAD CONSTRUCTION
11.3.1
Day 1
Figure 20 Sampler in position 1 near site entrance
Figure 21 Sampler in position 5 (circles) next to site fence near hand demolition
55
Figure 22 Sampler in position 2 (circles) – excavation and laying of hard core
Figure 23 Sampler in position 3 (circles) near hand demolition of shop
56
Figure 24 Site of urban air sample: The local authority TEOM site is behind the modern
building on the right
57
11.3.2
Day 2
Figure 25 Sampler at position 2 (squares) and proximity to the fence
Figure 26 Laying of road at position 1 (squares)
58
Figure 27 Sampler at position 3 (square) near the mosque and nightclub
(Short duration pneumatic drilling took place where workers are standing)
59
11.4
SITE 4: BLOCK CUTTING Figure 28 Sampler 2 with sampler 1 indicated with arrow in the background
Figure 29 Sampler 3 looking towards sampler 2
60
Figure 30 Moving sand for base of paving. The head of sampler 2 is seen in the
picture.
Figure 31 Cutting bricks with the cut-off saw. The hand pump is on the left-hand side of
the picture. Samplers 1 and 2 are slightly off shot behind the worker and the person
taking the picture. The edge of sampler 1 can just be seen behind the worker on the
left.
61
Figure 32 Table saw with reservoir tray in operation. The relative positions of this activity to the samplers are shown in Figure 28 Figure 33 The finished product – brick paving
62
11.5
SITE 5: BLOCK CUTTING Figure 34 Sampler in position 1b. Area of paving is enclosed with barriers.
Figure 35 Sampler in position 2 at the top of the area of the work
63
Figure 36 Laying of blocks in the pattern on sand. Sampler position 3 is behind the
person taking the picture.
11.6
SITE 6: RUBBLE CLEARANCE
Figure 37 JCB moving rubble and water suppression in background near sampler position 2
64
Figure 38 Position of sampler 1
Figure 39 Position of sampler 4 65
11.7
SITE 7: DEMOLITION Figure 40 Position of sampler 2 (circles)
Figure 41 Demolition activity
66
Figure 42 Movement of rubble near sampler 3
Figure 43 Location of urban air sampler position showing comparative height of PM10
and HSL respirable sampler inlets.
67
Figure 44 Water suppression from sampler 1 (squares)
Figure 45 Sampler at position 3 (squares)
68
Figure 46 Other activity down wind of the samplers
69
Published by the Health and Safety Executive
07/11
Health and Safety
Executive
Levels of respirable dust and respirable
crystalline silica at construction sites
The purpose of this pilot study was to assess the
potential for inadvertent exposure of the public to
respirable crystalline silica (RCS) from construction
activities.
The study assessed the respirable dust (RD) from,
demolition, block cutting, road building, general
construction activities and city centre air from 13 visits
to 7 sites. In total, 48 samples from the construction
activities and 11 city centre air samples, for comparison,
were collected.
The results obtained for RD and RCS were generally
very low. Only 10 % of results (from two sites) for RCS
were above 0.01 mg.m-3, which is 10 % of the current
Workplace Exposure Limit (WEL) for RCS. The majority
of visits showed evidence of some transport of RCS
across the site and potentially into public areas. The
main crystalline components of the city centre air
sample were generally the same as the components of
the samples taken at the construction sites.
This report and the work it describes were funded by
the Health and Safety Executive (HSE). Its contents,
including any opinions and/or conclusions expressed,
are those of the authors alone and do not necessarily
reflect HSE policy.
RR878
www.hse.gov.uk