Abstract：To investigate the indoor PM_2.5 concentration and its influence factors of residences in Tianjin, the article conducted a measurement on four families in different communities in Tianjin, as well as analyzed the main influence factors including the activities of indoor personnel, the cooking emission and the air purifier. The results show that the PM_2.5 concentration increases gradually along with the rise in staff activities, the cuisine causes 3 times the concentration of PM_2.5 before cooking and the PM_2.5 is reduced about 58% by opening air purifier.

Keywords: fine particwlate matter; indoor air quality; imfluence factor