Bioaerosols in residential micro-environments in low income countries: a case study from Pakistan

Our knowledge of the concentrations of bioaerosols in residential micro-environments in low income countries is scanty. The present investigation was conducted to assess the culturable concentration and size distribution of bacteria, gram-negative bacteria and fungi in two rural and an urban site in Pakistan. The highest indoor culturable bacteria concentration was found at Rural Site II (14,650 CFU/m3) while the outdoor maximum occurred at the urban site (16,416 CFU/m3). With reference to fungi, both indoor and outdoor concentrations were considerably higher at Rural Site I than the other sites. The size distribution of culturable bacteria at all sites showed greater variability than that of culturable fungi. At all sites more than half (55–93%) of the culturable bacterial and fungal counts were observed in the respirable fraction (<4.7 μm) and so had the potential to penetrate into lower respiratory system.