Particulate pollution in urban residential built environments during winter and summer seasons in Lahore, Pakistan

Indoor air pollution in urban residential areas of developing countries is of growing public health concern. The seasonal variation in mass concentration of PM<inf>1</inf>, PM<inf>2.5</inf> and PM<inf>10</inf>was investigated in a residential built environment in Lahore, Pakistan by two DustTrak aerosol monitor (model 8520, TSI Inc.) during the winter and summer season. The measurements were carried out in the kitchen and living room simultaneously.The 24-hr meanconcentrationsfor PM<inf>1</inf>, PM<inf>2.5</inf> and PM<inf>10</inf>in the kitchen and living room during the winter season were 157μg/m³ (±54), 733 μg/m³(±243), 409 μg/m³(±177) and 135μg/m³ (±39), 240 μg/m³ (±87), 300 μg/m³ (±115), respectively.During the summer the 24-hr mass concentration, for the same size fraction, in the kitchen and living room fell to 37μg/m³ (±4), 74μg/m³ (±11), 100 μg/m³ (±22) and31μg/m³ (±4), 71 μg/m³ (±19), 190 μg/m³ (±21), respectively. Apart from a higher concentration in winter than summer, a vast variation in 24hr and hourly mean concentration was also observed in the latter than in the former.Moreover background concentrations (hourly minimum) were also higher in winter than summer. These clearly highlight the impact of ventilation on indoor particulate matter as the sampling spaces (kitchen and living room) were more ventilated in summer than winter. The higher concentrationof the coarse size fraction in the living room than in the kitchen during summer time also shows the contribution from outdoor sources. These findings highlightthe impact of location, use and management of a residential built environment on exposure to indoor air pollutants.