Suchergebnisse

Abstract
The evidence of meteorological conditions on occupational exposure measurements is limited, despite is expected to be important determinants of long-term exposures. We describe meteorological conditions for measurement and non-measurement days and evaluate associations between temperature and total precipitation and respirable dust and respirable crystalline silica (RCS) concentrations of the European Industrial Minerals Association-Dust Monitoring Programme. Geo-matched RCS and dust measurements were evaluated against meteorological data (archived satellite observations and weather station measurements). Temperature(0C) and total precipitation (mm) for RCS measurement and non-measurement days were described. A linear regression model was used to investigate the association between dust and RCS concentration and meteorological conditions. Overall, 2,840 dust measurements (GM=0.20mg/m3; GSD=3.43mg/m3) and 2,658 quartz measurements (GM=0.01mg/m3; GSD=5.23mg/m3) were collected across 96 an 94 industrial mineral sites over 262 and 259 days in 2011. Mean temperature and precipitation for dust and RCS measurements were similar for measurement and non-measurement days (dust: 10.490C and 10.830C, 2.23mm and 2.12mm; RCS: 11.050C and 10.820C, 2.08mm and 2.12mm). For respirable dust concentrations a 6.4% decrease per 1°C was estimated for temperatures<200C (p<0.001) and an 8.2% increase for temperatures≥200C (p=0.002). For RCS a 2% decrease in was estimated for every 1mm increase in total precipitation (p=0.02). No difference in meteorological conditions were seen between measurements days and non-measurement days. Associations of these conditions with exposure concentrations with showed differences between agents despite being collected and measured on the same filter. Long-term changes in meteorological conditions might be an important factor when estimating long term exposures.

Abstract
We analyzed 34,790 simultaneously collected respirable dust and quartz measurements from April 1, 2002-March 31, 2021 at 158 sites across Europe and stored within the Industrial Minerals Association-Dust Monitoring Programme (IMA-DMP) database. From the European Centre for Medium-Range Weather Forecasts model we extracted 309,833 outdoor temperature, precipitation and windspeed data for the geocoded site addresses for the time period of this study, only weekdays were included. Meteorological conditions for measurement and non-measurement days were compared. Dust and quartz exposure levels were modeled with hierarchical linear mixed models with long-term time trend, temperature, precipitation and windspeed as fixed effects and mineral, site and job title as random effects.
Exposure measurements were collected over 10,863 days at 158 sites, representing 3.5% of days covered by IMA-DMP. Measurement and non-measurement days had slightly different meteorological conditions. Measurement days had slightly higher median temperature: 12.370C vs 11.060C, less median precipitation: 0.28mm v 0.31mm, and lower median outdoor wind speed: 2.13m/s vs 2.33m/s. Respirable dust concentrations decreased with increasing outdoor windspeed and precipitation (respectively 11% and 6% per 10 mm). For respirable quartz the effect was stronger (respectively 17% and 16% per 10 mm). The effect of temperature was marginal for respirable dust, but above 60C respirable quartz concentrations decreased rapidly with 50% per 100C.
Marginal differences in meteorological conditions were seen between measurements days and non-measurement days. Respirable quartz concentrations were more sensitive to meteorological conditions. Long-term changes in meteorological conditions (climate change) might affect indoor workplace respirable dust and especially respirable quartz concentrations.

Abstract

Objectives
To use the recently developed Ontario Mining Exposure Database (OMED) to describe historical silica exposure in the Ontario metal mining industry and identify predictors of historical silica exposure.


Methods
Personal respirable crystalline silica (RCS) data for metal mines were extracted from OMED and included both individual and summary measures, where multiple exposure measurements (n > 1) were aggregated and entered as a single exposure value (n = 1). Data were stratified by sample location (underground/surface) for analysis. Monte Carlo simulation was used to simulate individual measures from the summary measures. A fixed effects multiple linear regression model was used to assess the effects of commodity (ore mined), sample year, source of exposure data, and occupational group on RCS concentration. Parameter estimates (β), standard errors, and 95% upper and lower confidence intervals were reported.


Results
The OMED contained 12 995 silica measurements. After limiting to RCS measurements in metal mines, and measures with sufficient information for analysis, 2883 RCS measurements collected from 1974 to 1991 remained, including 2816 individual and 67 summary measurements. In total, 321 individual RCS measurements were simulated from the 67 summary measures. The analysis database contained 2771 (12% simulated) underground measurements and 366 surface measurements (0% simulated). In the underground group, an overall geometric mean (GM) of 0.05 [geometric standard deviation (GSD) 3.09] mg m−3 was estimated with a 6% annual decrease over time. In this group, the commodity with the highest average RCS level was zinc mines (GM = 0.07 mg m−3) and the lowest was iron mines (GM = 0.01 mg m−3). In the surface group, an overall GM of 0.05 (GSD 3.70) mg m−3 was estimated with an 8% decreased over time. In this group, the commodity with the highest average RCS level was gold mines (GM = 0.07 mg m−3) and the lowest was zinc mines (GM = 0.03 mg m−3). In both groups, company collected data had lower estimated RCS compared with regulator collected data.


Conclusions
Historical RCS levels decreased over time. Mean measurements exceeded the American Conference of Governmental Industrial Hygienists current health-based threshold limit value (0.025 mg m−3). The main predictors of exposure were commodity, source of exposure data, and sample year. However, low R2 and high GSD values suggest additional predictors of RCS exposures in Ontario's metal mines exist that were unavailable in OMED.

Abstract

Objectives
Diesel engine exhaust (DEE) is a known lung carcinogen and a common occupational exposure in Canada. The use of diesel-powered equipment in the construction industry is particularly widespread, but little is known about DEE exposures in this work setting. The objective of this study was to determine exposure levels and identify and characterize key determinants of DEE exposure at construction sites in Ontario.


Methods
Elemental carbon (EC, a surrogate of DEE exposure) measurements were collected at seven civil infrastructure construction worksites and one trades training facility in Ontario using NIOSH method 5040. Full-shift personal air samples were collected using a constant-flow pump and SKC aluminium cyclone with quartz fibre filters in a 37-mm cassette. Exposures were compared with published health-based limits, including the Dutch Expert Committee on Occupational Safety (DECOS) limit (1.03 µg m−3 respirable EC) and the Finnish Institute of Occupational Health (FIOH) recommendation (5 µg m−3 respirable EC). Mixed-effects linear regression was used to identify determinants of EC exposure.


Results
In total, 149 EC samples were collected, ranging from <0.25 to 52.58 µg m−3 with a geometric mean (GM) of 3.71 µg m−3 [geometric standard deviation (GSD) = 3.32]. Overall, 41.6% of samples exceeded the FIOH limit, mostly within underground worksites (93.5%), and 90.6% exceeded the DECOS limit. Underground workers (GM = 13.20 µg m−3, GSD = 1.83) had exposures approximately four times higher than below grade workers (GM = 3.56 µg m−3, GSD = 1.94) and nine times higher than above ground workers (GM = 1.49 µg m−3, GSD = 1.75). Training facility exposures were similar to above ground workers (GM = 1.86 µg m−3, GSD = 4.12); however, exposures were highly variable. Work setting and enclosed cabins were identified as the key determinants of exposure in the final model (adjusted R2 = 0.72, P < 0.001). The highest DEE exposures were observed in underground workplaces and when using unenclosed cabins.


Conclusions
This study provides data on current DEE exposure in Canadian construction workers. Most exposures were above recommended health-based limits, albeit in other jurisdictions, signifying a need to further reduce DEE levels in construction. These results can inform a hazard reduction strategy including targeted intervention/control measures to reduce DEE exposure and the burden of occupational lung cancer.