Seasonal and Diurnal Variations of Indoor PM2.5 in Six Households in Akure, Nigeria

Abstract

Seasonal, diurnal, and site-to-site variations in indoor PM2.5 concentrations in Akure, a city in southwestern Nigeria, are investigated by continuous observations using low-cost sensors in six households. Significant seasonal variations were observed, with the highest monthly PM2.5 concentrations occurring in the dry season, both indoors and outdoors. Significant seasonal variations with higher PM2.5 levels during the dry season were observed, with mean PM2.5 concentrations of 55 μg/m3 in the kitchen and 48 μg/m3 in the living rooms, compared to those during the wet season (23 μg/m3 in the kitchen and 14 μg/m3 in the living rooms). The kitchen-to-outdoor and indoor-to-outdoor PM2.5 ratios increased particularly during the morning and evening hours at several sites, suggesting significant contributions from cooking activities in the kitchen, as well as the transfer of PM2.5 into the living room. An assessment of PM2.5 exposure risks among 32 residents in the studied households revealed higher risks among individuals who cook routinely. This study underscores the importance of addressing indoor air pollution alongside outdoor pollution, particularly by improving ventilation and reducing cooking emissions, to effectively minimize exposure risks.