Levels of indoor particulate matter and association with asthma in children in Benin City, Nigeria.

The relationship between indoor particulate matter and asthma in children was assessed in this study. Forty-five (45) locations were randomly selected across the five local government areas in Benin City, Edo State, for air quality assessment. Indoor and outdoor particulates (PM, PM, and PM) were monitored monthly using a handheld BLATN particulate sampler (Br-Smart-126S series). Reported clinical cases of asthma in children from 2008 to 2017 were collected from two major hospitals in the metropolis. The data obtained were analysed with SPSS for Windows version 21.0. The average concentrations of indoor and ambient PM ranged between 10.7-26.2 and 19.0-49.4 µg/m (PM), 27.4-59.6 and 45.6-93.0 µg/m (PM), and 33.5-67.9 and 60.9-106.1 µg/m (PM) in the wet and dry seasons. PM and PM concentrations were observed above the WHO standards. Indoor particulate concentration was significantly (p = 0.001-0.012) higher in the dry season across the locations. Outdoor PM correlated positively (R = 0.568-0.855, p < 0.05; R = 0.322-0.724, p < 0.001) with their corresponding indoor PM concentration. The hazard ratio (HR) values of PM and PM exceeded 1 in all the sampling locations during the dry season, while the mean total hazard ratio (THR) of both PM metrics was considerably higher during the dry season than in the wet season. Indoor PM concentrations showed a significant positive correlation with reported cases of asthma (R = 0.498-0.542, p < 0.001) and accounted for 40.6% of the asthma cases during the dry season. The study showed that children in the selected households are at risk of increased asthma exacerbation due to exposure to particulate matter pollution.