Exposure patterns of PM2.5 and CO concentrations in residential and commercial buildings: factors influencing indoor air quality
摘要
Indoor air pollution is a growing concern as people spend most of their time indoors. However, information on indoor air quality and factors influencing indoor exposures remains limited, particularly in rapidly urbanizing cities like Kigali, Rwanda. To address this gap, this study examined the distribution of carbon monoxide (CO) levels and fine particulate matter (PM2.5) in residential and commercial buildings. Indoor and outdoor PM2.5 and CO concentrations. Along with meteorological variables such as relative humidity (RH) and temperature, were measured every two minutes over 24-h period during both dry and wet seasons. PM2.5 measurements were conducted from March to August 2024 in residential and commercial buildings, CO measurements were conducted from June to August 2024 in 88 households across urban, suburban, and industrial zones. The study found significantly higher PM2.5 levels during the dry season, with indoor levels averaging 40.2 ± 19.3 μg/m3 and outdoor levels 41.3 ± 17.5 μg/m3, compared to the wet season, where indoor levels were 32.8 ± 82.9 μg/m3 and outdoor levels 35 ± 15.8 μg/m3 outdoors. CO levels were consistently higher outdoors (691.3 ± 181.8 μg/m3) than indoors (478.4 ± 128.2 μg/m3). Indoor/outdoor (I/O) ratios for PM2.5 were consistently below 1, indicating a strong influence of outdoor sources on indoor PM2.5 levels. While, location type showed a slight correlation with PM2.5 concentrations, building features such as age, window count, and ventilation exhibited varying but insignificant impacts. These findings highlight the critical role of outdoor pollution and meteorological factors in determining indoor air quality in Kigali and underscores the need for regulating outdoor pollution sources and indoor environments.