Urban aerosol studies of PM1 size fraction with reference to ambient conditions and visibility

Abstract

Mass measurement of ambient PM10 and PM2.5 size fractions is a rather well established technique. However there is a broad consensus in the scientific community about the importance of smaller particle size fractions regarding epidemiological and environmental aspects. We present aerosol mass measurement performed with two different aerosol impactors operated simultaneously - a commercial real cascade impactor and a custom made cascade virtual impaction plate impactor. Both instruments have size segregation for 10, 2.5 and 1 μm in terms of an aerodynamic diameter, hence corresponding to PM10, PM2.5 and PM1. Furthermore the Vienna Telephotometer delivers information about the extinction coefficient in the vicinity of local particle sampling. The time-resolved size distributions of the PM1 fraction are measured by means of the scanning differential mobility analyzer and are merged with the time-resolved aerosol extinction coefficient data in the area of interest, along with the particle surface and mass concentration measurement. Results show the importance of time resolved measurement of the PM1 size fraction and indicate a good correlation between the ratio of PM1 to PM2.5 and PM10 with the extinction coefficient. Copyright © Taiwan Association for Aerosol Research.