RR878 - Levels of respirable dust and respirable ...

1 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.

2 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 , 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).

3 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 charge in any format or medium, under the terms of the Open Government Licence. To view the licence visit , write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email Some images and illustrations may not be owned by the Crown so cannot be reproduced without permission of the copyright owner. Enquiries should be sent to 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.

4 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 1 respirable 2 Previous evidence.

5 2 2 AIR SAMPLING 3 The 3 Calibration of sampler for the respirable fraction .. 3 Variability of the five samplers .. 5 Monitoring strategy .. 5 3 ANALYSIS 7 Gravimetric analysis for respirable 7 RCS analysis method for ambient 7 4 DESCRIPTION OF CONSTRUCTION SITES AND RESULTS .. 10 Site 1: General Construction 10 Site 2: Demolition .. 13 Site 3: City Centre ring road Construction .. 18 Site 4: Street block cutting .. 23 Site 5: Street block cutting .. 25 Site 6: Rubble Clearance from 27 Site 7: Demolition of College .. 30 5 COMPARISON WITH TEOM 34 6 crystalline COMPONENTS OF URBAN AIR.

6 35 7 38 Summary of 38 respirable Dust .. 39 Weight of dust recovered from ashing .. 40 respirable crystalline Silica .. 40 Transport of dust across the 41 8 44 9 46 10 APPENDICES 1: XRD 48 11 APPENDIX 2 .. 49 Site 1 Construction .. 49 Site 2 Demolition .. 51 Site 3: Ring road 55 site 4: Block 60 Site 5: Block Cutting .. 63 Site 6: Rubble 64 iii Site 7: Demolition .. 66 iv 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.

7 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.

8 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 ). The regression coefficient (r2) excluding extreme values was The main crystalline components of urban air samples are quartz (SiO2), calcite (CaCO3), halite (NaCl), anhydrite (CaSO4) and/or calcium sulphate hydrate ( ). Some urban air samples also showed peaks that indicated the presence of clays (illite and kaolinite) and probably hematite (Fe2O3).

9 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 %).

10 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 Despite dust controls, large-scale demolition projects, with excavators, have the potential to produce air concentrations of respirable dust in excess of 50 (Maximum 226 ). This is probably because the contractors find it difficult to introduce effective and consistent dust controls because of the scale of the task.