In order to study the level and size distribution of microbial activity of atmospheric bioaerosols,bioaerosol samples were collected from November 2015 to January 2016 using size-fractionated bioaerosol samplers at the coastal region of Qingdao,and the microbial activity was measured using the fluorescein diacetate( FDA) hydrolysis method. The results showed that the level of microbial activity was in the range of 21. 89-108. 59 ng·m~(-3)sodium fluorescein during the sampling period,with an average of 59. 4...