People spend about 80-90% of their time indoors, and graduate students of academic institutes could spend up to 15 hours per day in their offices.
People spend about 80-90% of their time indoors, and graduate students of academic institutes could spend up to 15 hours per day in their offices. Compared to outdoor air quality, the air quality of the office is more relevant to their health. Therefore, understanding the levels, sources and evolution of particulate matter (PM) indoors is of great importance for the accurate evaluation of the students' health risks to aerosol exposure.
Professor SUN Yele and his team at the CAS Institute of Atmospheric Physics deployed a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) to measure time series and mass spectra of non-refractory species in a typical academic office located at the Institute of Atmospheric Physics. The concentration and chemical composition of indoor PM2.5 were measured for one month along with simultaneous measurements outdoors. They also performed the open-close window and the dampness experiments in order to figure out the mechanism of indoor/outdoor air exchange, and the influence of increased humidity on the indoor PM2.5.
They found that the indoor aerosol species are primarily from outdoor air exchange. "The indoor and outdoor variation trends are similar for most of aerosol species," said Prof. SUN, "However, the chemical compositions of PM2.5 are different. The concentration of organic aerosol from fossil fuel combustion and ammonium nitrate decreases because they evaporate or turn from particle to gas upon transport indoors when the indoor temperature is much higher than outside in winter."
Read more at Institute of Atmospheric Physics, Chinese Academy of Sciences
Image: Sources and evolution of particulate matter in the indoor environment. (Credit: Junyao Li)
