Occupational Exposure to Diesel Particulate Matter in Municipal Household Waste Workers

<div><p>Objective</p><p>The purposes of this study were to determine the following: 1) the exposure levels of municipal household waste (MHW) workers to diesel particulate matter (DPM) using elemental carbon (EC), organic carbon (OC), total carbon (TC), black carbon (BC), and fine particulate matter (PM 2.5) as indicators; 2) the correlations among the indicators; 3) the optimal indicator for DPM; and 4) factors that influence personal exposure to DPM.</p><p>Methods</p><p>A total of 72 workers in five MHW collection companies were assessed over a period of 7 days from June to September 2014. Respirable EC/OC samples were quantified using the thermal optical transmittance method. BC and PM 2.5 were measured using real-time monitors, an aethalometer and a laser photometer. All results were statistically analyzed for occupational and environmental variables to identify the exposure determinants of DPM.</p><p>Results</p><p>The geometric mean of EC, OC, TC, BC and PM 2.5 concentrations were 4.8, 39.6, 44.8, 9.1 and 62.0 μg/m³, respectively. EC concentrations were significantly correlated with the concentrations of OC, TC and BC, but not with those of PM 2.5. The exposures of the MHW collectors to EC, OC, and TC were higher than those of the drivers (p<0.05). Workers of trucks meeting Euro 3 emission standard had higher exposures to EC, OC, TC and PM 2.5 than those working on Euro 4 trucks (p<0.05). Multiple regression analysis revealed that the job task, European engine emission standard, and average driving speed were the most influential factors in determining worker exposure.</p><p>Conclusions</p><p>We assessed MHW workers’ exposure to DPM using parallel sampling of five possible indicators. Of these five indicators, EC was shown to be the most useful indicator of DPM exposure for MHW workers, and the job task, European emission standard, and average driving speed were the main determinants of EC exposure.</p></div

Photographs of municipal household waste-collecting activities.

<p>Left: Riding on the rear of a truck. Right: Collecting MHW with samplers mounted.</p

Geometric mean of TC and OC/EC according to job task, smoking habit, and type of truck.

<p>The geometric mean TC is presented as a bar chart. Each bar is the sum of EC (ivory bar) and OC (gray bar). The mean levels of TC for the collectors, smokers, workers on larger trucks and on trucks meeting Euro Standard 3 were significantly higher than those of the drivers, non-smokers, workers on smaller trucks, and those working on trucks meeting Euro Standard 4. The OC/EC is shown at the end of each bar. The OC/EC ratios for smokers, workers on larger trucks, and workers on trucks that had greater distances between the tailpipe and rear of the truck were significantly higher than those for the other categories of workers.</p

Correlation coefficients among levels of EC, OC TC, BC and PM 2.5.

<p>¹⁾ p<0.01 correlation is significant at the 0.01 level (one-tailed).</p><p>²⁾ p<0.05, correlation is significant at the 0.05 level (one-tailed).</p><p>³⁾ p<0.001 correlation is significant at the 0.001 level (one-tailed).</p><p>Abbreviations: EC: elemental carbon; OC: organic carbon; TC: total carbon; BC: black carbon; PM 2.5: particulate matter 2.5</p><p>Correlation coefficients among levels of EC, OC TC, BC and PM 2.5.</p

Association between humidifier disinfectant exposure-related characteristics and HDLI risk.

<p>Association between humidifier disinfectant exposure-related characteristics and HDLI risk.</p

Humidifier disinfectant use characteristics by HDLI case and control and age group.

<p>Humidifier disinfectant use characteristics by HDLI case and control and age group.</p

Associations with HDLI for confounding factors.

<p>Associations with HDLI for confounding factors.</p