Diesel engine exhaust exposures in two underground mines

Exposure to diesel engine exhaust(DE) is a major concern in underground mines. It has been linked to cardiopulmonary diseases and is classified as a human carcinogen. The goal of this study is to assess DE exposures in workers at two underground gold mines, to compare exposure levels within and between the mines, and to compare different methods of measuring DE exposures, namely respirable combustible dust(RCD), elemental carbon(EC) and total carbon(TC). Ambient and personal breathing zone(PBZ) measurements were taken. Side-by-side monitoring of RCD and of the respirable fraction of EC and TC(EC_Rand TC_R) was carried out in the workers' breathing zone during full-shift work.Regarding ambient measurements, in addition to EC_R, TC_Rand RCD, a submicron aerosol fraction(less than 1 mm) of EC and TC was also sampled(EC_1and TC_1). Average ambient results of 240 mg/m^3 in RCD, 150 mg/m^3 in EC_Rand 210 mg/m^3 in TC_Rare obtained. Average PBZ results of 190 mg/m^3 in RCD,84 mg/m^3 in EC3Rand 150 mg/min TC_Rare obtained. Very good correlation is found between EC_Rand EC_1 with a Pearson correlation coefficient of 0.99(p < 0.01) calculated between the two logtransformed concentrations. No differences are reported between EC_Rand EC_1, nor between TC_Rand TC_1, since ratios are equal to 1.04, close to 1, in both cases. Highest exposures are reported for loadhaul-dump(LHD) and jumbo drill operators and conventional miners. Significant exposure differences are reported between mines for truck and LHD operators(p < 0.01). The average TC_R/EC_Rratio is 1.6 for PBZ results, and 1.3 for ambient results. The variability observed in the TC_R/EC_Rratio shows that interferences from non-diesel related organic carbon can skew the interpretation of results when relying only on TC data.

Experimental investigation on PM2.5 particle emission during polishing of granite

Particle emission during manufacturing processes, whether chemical, physical or mechanical can represent a serious danger for environment and for occupational safety. Especially machining processes, particle emission could have an important impact on shop floor air quality and might jeopardise workers’ health. It is therefore important to find ways of reducing the particle emission at the source of manufacturing processes. To do so, there is a need to know the size, the quantity and the distribution of particles produced by processes currently used in industry. In this study, investigations are done to compare the particle emission (PM2.5) when polishing two granites (black and white). The black granite contained low Si concentration (about 10% Si) and the white granite contained high Si concentration (about 50% Si). Particle emission was monitored using the DustTrak II equipment with 2.5 μm impactor. The particle grain size was evaluated using X-ray diffraction techniques. Machining conditions leading to the generation of finer particles were identified.

Human viral pathogens are pervasive in wastewater treatment center aerosols

Wastewater treatment center（WTC） workers may be vulnerable to diseases caused by viruses, such as the common cold, influenza and gastro-intestinal infections. Although there is a substantial body of literature characterizing the microbial community found in wastewater, only a few studies have characterized the viral component of WTC aerosols,despite the fact that most diseases affecting WTC workers are of viral origin and that some of these viruses are transmitted through the air. In this study, we evaluated in four WTCs the presence of 11 viral pathogens of particular concern in this milieu and used a metagenomic approach to characterize the total viral community in the air of one of those WTCs. The presence of viruses in aerosols in different locations of individual WTCs was evaluated and the results obtained with four commonly used air samplers were compared.We detected four of the eleven viruses tested, including human adenovirus（h Ad V）,rotavirus, hepatitis A virus（HAV） and Herpes Simplex virus type 1（HSV1）. The results of the metagenomic assay uncovered very few viral RNA sequences in WTC aerosols, however sequences from human DNA viruses were in much greater relative abundance.