Household PM2.5 pollution in rural Chinese homes: Levels, dynamic characteristics and seasonal variations

Humans generally spend most of their time indoors, and fine particulate matter (PM2.5) in indoor air can have seriously adverse effects on human health due to the long exposure time. This study conducted field measurements to explore seasonal variations of PM2.5 concentrations in household air by revisiting the same rural homes in southern China and factors influencing indoor PM2.5 concentrations were explored mainly by one-way ANOVA. The PM2.5 concentrations of outdoor, kitchen and living room air were 38.9 ± 12.2, 47.1 ± 20.3 and 50.8 ± 24.1 μg/m3 in summer, respectively, which were 2.3 to 2.9 times lower than those in winter (p < 0.05). The lower indoor PM2.5 pollution in summer was attributed to the transition to clean household energy and better ventilation. Fuel type can significantly affect PM2.5 concentrations in the kitchen, with greater PM2.5 pollution associated with wood combustion than electricity. Our study firstly found mosquito coil emission was an important contributor to PM2.5 in the living room of rural households, which should be investigated further. Dynamic variations of PM2.5 suggested that cooking, heating and mosquito coil emission can rapidly increase indoor PM2.5 concentrations (up to one order of magnitude higher than baseline values), as well as the indoor/outdoor PM2.5 ratios. This study had the first insight of seasonal differences of household PM2.5 in the same rural homes using real-time monitors, confirming the different patterns and characteristics of household PM2.5 pollution in different seasons.