The association between intermodal (PM1-2.5) and PM1, PM2.5, coarse fraction and meteorological parameters in various environments in central Europe
Abstract
Fine and coarse fractions of atmospheric aerosol overlap in the particle size range of about 1-2.5 µm (aerodynamic diameter). Sources of both fractions contribute to PM(1-2.5) to different extents due to meteorological and spatial conditions.
Therefore, there is ongoing discussion as to whether PM(2.5) or PM(1) should be included for monitoring as a fine particulate pollutant by the national ambient air quality standard (NAAQS). The aim of the presented article is to examine the association between the intermodal and PM(1), PM(2.5), coarse fraction, and meteorological parameters in various environments.
Outdoor 24-h mass concentrations of size-resolved PM and meteorological conditions were measured at 12 sites within 42 campaigns between 11/2005 and 3/2015. The data set was divided into 10 environments reflecting season, locality, total measured PM, and placement of the impactor.
We used two types of statistic methods: nonparametric correlation analysis and multiple linear regression (MLR). Median PM(1-2.5) in PM(10) or TSP percentages were 7% and 6% in summer and 7% and 9% in winter.
On the other hand, PM(1-2.5) accounted for a higher mass portion of PM(2.5) during summer. Stronger positive correlation and relationship were identified between PM(1-2.5) and the coarse fraction than between PM(1-2.5) and PM(1) in all environments.
MLR confirmed the dependence of PM(1-2.5) on PM(1) in only 3 environments. This study found that PM(1-2.5) in Central Europe represents mostly the "tail" of the coarse mode and probably has the same sources.
Therefore, PM(1) should be considered by the NAAQS as a fine particulate pollutant in Central Europe.