Abstract:[Background] PM2.5 has many toxic effects that seriously damage organisms with long-term exposure. However, few studies have found a simple method to measure its microbial activity, although microorganisms are the important biological components of PM2.5. [Objective] Few developed a fluorescein diacetate hydrolysis method to test microbial activity in atmospheric PM2.5 through a large number of experiments and simulations. [Methods] We optimized and determined main testing parameters. Samples were collected by using an OMNI FTTM Ambient Air Sampler with a flow rate of 5 L/min for 40 min. The concentration of fluorescein diacetate was 200 μg/ml, and acetone was added to stop the reaction after 1.5 hours in dark environment. Microbial activity in atmospheric PM2.5 was measured after 15 min. [Results] Microbial activity in outdoor and indoor PM2.5 in July 2017 was with the average of 0.873 ng/m3 and 1.110 ng/m3 sodium fluorescein. [Conclusion] This paper established an effective and accurate method to measured microbial activity in atmospheric PM2.5.
