Bioaerosol emissions from a suburban yard waste composting facility.

The purpose of this study was to assess worker and community exposure to bioaerosols emitted from a suburban yard waste composting facility in northern Illinois, USA. Characterization of on- and off-site viable bioaerosols was undertaken through a total of 288 on- and off-site Andersen samples conducted over 10 sampling days. A total of 46 dust samples and 38 Kramer-Collins spore samples were also collected in this period. Evaluation of the impact of the facility on community bioaerosol concentrations was undertaken by comparing on- and off-site measurements by sampling locations, wind direction, and site activity. On-site concentrations of total spores, Aspergillus/Penicillium spores, total bacteria, Gram-positive bacteria, Gram-negative bacteria, actinomycetes, total particulates, endotoxin, and beta-1,3 glucans were higher than off-site concentrations. Total fungal spores averaged 13,451 spores/m3 (range 5,223-26,067) on-site and 8,772 spores/m3 (range 243-18,276) off-site. Viable bacterial airborne concentrations (in cfu/m3) averaged 11,879 on-site (range 480-78,880) and 3,204 off-site (range 160-17,600). Mean levels of endotoxins (in ng/m3) were 1.94 on-site (range 0.12-6.06) and 0.14 off-site (range 0.01-0.41). Mean levels of beta-1,3 glucans (in ng/m3) were 2.17 on-site (range 0.12-14.45) and 0.24 off-site (range 0.01-0.78). Mean total viable fungi, on the other hand, were higher off-site than on-site (8,651 vs 3,068 cfu/m3). On-site concentrations of total bacteria, Gram-positive bacteria, Gram-negative bacteria, and actinomycetes demonstrated a statistically significant pattern of decreasing concentration with distance from pile and higher downwind vs upwind concentrations. Mean on-site concentrations of viable bacteria, viable fungi, and endotoxins were significantly higher during periods of activity compared to periods of no activity. Off-site concentrations of bacteria were also significantly higher during periods of activity compared to no activity. The highest concentrations of total particulates, endotoxin, and beta-1,3-glucans were observed in the personal samplers worn by workers at the facility. One personal sampler measured an Asp f1 exposure of 22.17 ng/m3 during turning activity. Peak exposures to several bioaerosol constituents were sufficiently high to warrant use of respirators by workers during periods of pile activity that lead to dust generation.