Introduction
The epidemiological studies have indicated that PM2.5 can increase morbidity and mortality, damage the
respiratory system and the cardiovascular system, and affect the immune function and so on [1]. The research
showed that the people spent more than 90% time indoors [2]. Indoor environment is particularly important to the
human health. The research on indoor particulate matter is getting more and more attention.
The objectives of this study are to understand PM2.5 pollution status in the households when the heavy air
pollution occurs in the winter and the correlation of indoor PM2.5 pollution with outdoor, and to find out the
effect of indoor human activities on the changes of indoor PM2.5 concentrations.
2. Methods
Outdoor sampling point is Guanyuan environmental pollution monitoring station, Xicheng district, Beijing. 1
Indoor sampling point is in the living room, about 1.5m height from the ground. The linear distance from indoor
sampling point to outdoor sampling point is about 1km. The portable PM2.5 sampler (CLH-2000, the flow rate is