Bioaerosol levels and the indoor air quality of laboratories in Bangkok metropolis

Bioaerosols are major air pollutants commonly found both indoors and outdoors. High exposure levels may result in various adverse health outcomes. Laboratories, which are indoor environments carefully designed for specific purposes, may contain high levels of bioaerosols, which may threaten worker's health, and contaminate experimental results. This study investigated the levels of bioaerosols (i.e., culturable fungi and bacteria, and fungal spores) in laboratories in the Bangkok metropolitan area. Air samples were collected from 14 Class I and one Class II laboratories by using a single-stage impactor and a VersaTrap spore trap cassette. Colonies were counted after 72h and 48h of incubation for culturable fungi and bacteria, respectively. Culturable fungi and fungal spores were identified based on their morphological characteristics. Associations between bioaerosols and indoor air parameters and laboratory characteristics were evaluated. The concentrations (mean +/- SD) of culturable bacteria, culturable fungi, and fungal spores were 87.0 +/- 97.8CFU/m(3), 294.9 +/- 376.1CFU/m(3), and 771.8 +/- 545.3 spores/m(3), respectively. Aspergillus/Penicillium, ascospores, and Cladosporium were common fungal spore taxa in the laboratories. Culturable fungi significantly increased with the number of staff and visible molds, whereas water leaks and culturable fungi significantly increased fungal spore concentrations. Culturable bacteria were positively associated with the numbers of trash bins and -80 degrees C freezers. Although bioaerosol concentrations were considerably lower in the studied laboratories, proper indoor air management is still suggested in order to reduce emissions and exposure. This can help workers avoid adverse health outcomes and reduce the chance of experimental contamination.