Introduction: Bioaerosols are one of major sources of hospital-acquired infections (HAI's) that can pose serious health implications to the patients, health care workers and visitors in the hospitals across the world. Methodology: In this study, the molecular identification and phylogenetic analysis of bioaerosols collected from Orthopedic Wards (OW) and Orthopedic Emergency Rooms (OER) of six hospitals in Lahore, Pakistan was done to investigate their diversity and genetic relatedness. Moreover, the role of different ventilation practices (i.e., centrally air-conditioned and non-central air-conditioned) in determining bioaerosols load was evaluated by using both culture and non-culture based (Flow cytometry) approaches. Results: The molecular characterization based on 16S rRNA gene and phylogenetic analysis of frequently recovered bacterial isolates showed 97-99% similarity to diverse sources i.e., air, soil and clinical strains isolated from various countries. The centrally air-conditioned hospitals had significantly lower levels of bioaerosols at most of the sites as compared to non- central air-conditioned hospitals. Conclusions: The molecular characterization and phylogenetic analysis based on 16S rRNA gene sequences can be effective tool in identifying nature and evolution of bioaerosols, and can improve infection control and surveillance in hospitals. The observed levels of bioaerosols suggest hospitals equipped with central air conditioners have considerably more air hygiene compared to non-central air conditioning systems. These findings are imperative for informing policies on planning and implementation of infection control strategies in hospitals in resource limited settings.

The presence of micro-organisms in air is taken for granted, but understanding the identities, distribution and abundance of airborne micro-organisms remains in its infancy. Indoor exposure to micro-organisms has been related to range of adverse health outcomes. The indoor levels of particulate matter and bioaerosols were monitored in thirty houses across Lahore, Pakistan. Two DustTrak aerosol monitors (model 8520, TSI Inc.) were run simultaneously in the kitchens and living rooms of the selected sites to measure fine particulate matter. At the same time, agar coated petri plates were exposed face upwards for twenty minutes to sample the micro-organisms present in surrounding air of both micro-environments. A total of 7 bacterial species and 11 fungal species were identified including Staphylococcus spp., Bacillus spp., Micrococcus spp. and Serratia spp. while the predominant fungal species were Alternaria alternata and Aspergillus spp. The concentrations (cfu m ranged between 236 and 1887 in the kitchen and from 315 to 1887 in the living room. A seasonal variation in bioaerosols was evident in the kitchens while being not so pronounced in the living rooms. A linear regression model showed a direct association of temperature with bacteria and fine particulate matter but not with fungi. Ventilation was also observed to have a significant impact upon PM levels. Out of 30 households sixteen had the presence of at least one individual with allergenic reactions. These findings highlight the enhanced risk of exposure to fine particulate matter as well as bioaerosols in the urban residential built environment in Pakistan.

Shifting seasons greatly influence the use and management practices in residential built environments which subsequently affect the level of exposure to various pollutants indoors. The levels of fine particulate matter (PM2.5) were monitored in fifteen households of Lahore, Pakistan during different seasons. DustTrak aerosol monitors (model 8520, TSI Inc.) were run simultaneously in the kitchens and living rooms of the selected sites for seventy two hours each. To aid analysis, houses were categorized in three groups according to floor area. For non-smoking houses there was little variation between 24 h average PM2.5 concentrations in kitchens (270 to 295 μg/m³) although there was an increase in concentrations in living rooms as floor area increased. Across all houses the average PM2.5 concentration was observed to vary during the seasons. In the kitchens the average PM levels were 326 μg/m³ during the spring falling to 133 μg/m³ in summer, 180 μg/m³ in monsoon, 395 μg/m³ in autumn and 448 μg/m³ during the winter. Similarly, in the living rooms, the mean PM levels observed were 190 μg/m³ in spring, 101 μg/m³ in summer, 158 μg/m³ in monsoon, 458 μg/m³ in autumn and 590 μg/m³ in winter. Factors contributing towards these levels were cooking (involving frequent frying), floor sweeping, and also movement of the occupants. Smoking at two sites and use of gas heaters during the winter were also identified as contributing sources. Apart from these sources, ventilation was identified to be the most singular attributing factor to the above mentioned variations in PM levels. Ventilation during the warm season ranged from 3.51 air changes per hour (ACH) to 7.68 ACH. On the contrary, ventilation decreased during the autumn and winter season (2.5 to 5.64 ACH) and this resulted in an accumulation of PM indoors. The levels of fine particulate matter were observed to be 3 to 23 times higher than the WHO established standard of 25 μg/m³.