Assessment of Indoor Air Quality and Influence of Ultra-fine Particles (PM1) on Lung Function in Residential Houses in Dhaka, Bangladesh

The effect of indoor air pollutant on health can surpass the outdoor pollutant as people spend most of their time in indoor environment, which made it one of the weightiest topics of air pollution research. The previous studies done on indoor air quality of Dhaka only focused on a certain area and specific community. There is also lack of studies about the diurnal variation of indoor pollutants at Dhaka city, which need to be accessed for mitigation policy. Furthermore, an extensive study on health impact of different pollutant yet needs to be done.

Concentration of particulate matters (PM) in different size fraction (PM₁, PM_2.5, PM₄, PM₇, PM₁₀ and TSP), NO₂ and total volatile organic compound (TVOC) from residential houses at five different locations of the Dhaka city were measured during the periods of August to October, 2017. The samples were also collected in a dual channel dust sampler (IPM-FDS 2510) and analyzed for trace metals. Respiratory function of the occupants was assessed by using a peak expiratory flow meter. The mean PM₁ concentration found in indoor environment of Dhaka is 46.1±13.4 The average PM_2.5 and PM₁₀ concentration for houses of Dhaka was 75.9±16.2 and 203.9±44.7 μgm^-3, respectively, which is several times higher than the WHO standards. Higher enrichment of Pb, Zn and Ni were observed in PM₁₀ due to traffic, industrial and constructional activities. A relatively weak correlation between indoor and outdoor PM_2.5 (R²=0.42) suggest indoor air is influenced by outdoor air which contributes 42% outdoor PM. The Indoor/Outdoor (I/O) ratios were less than one also indicating that outdoor PM is responsible for indoor pollution. Concentration of NO₂ (0.076±0.007 ppm) and TVOC (90.0±46.0 ppm) were found above other studies. Average total hazard ratio (THR) of Dhaka is 9.06 and highest exposure to air pollutants (PM_2.5, PM₁₀, NO₂) for Khilkhet residents were indicated by THR (10.10) than other sites. A negative association between PM_1.0 and peak flow rate of residence living in the houses under study indicates that inhalations of ultra-fine particles may be responsible for reduced lung efficiency. This study confirms that the reduced lung function of the occupants in the houses of Dhaka were due to high exposure of fine PM in indoor environment.