Winter sources of PM 2.5 pollution in Podkowa Leśna, a Central-European garden town (Mazovia, Poland).

The paper analyzes PM 2.5 aerosol samples collected in Podkowa Leśna, a garden town in Mazovia, Central Poland, for 15 days in winter 2019. We determined the mass concentrations in the air of PM 2.5 and PM 2.5 -bound organic carbon, elemental carbon, levoglucosan, and nine polycyclic aromatic hydrocarbons (PAHs). PM 2.5 ranged from 11 to 51 μg m -3 (mean 31 μg m -3 ) and contained less than 32% organic carbon, 4% elemental carbon, 1% levoglucosan, and 0.12% total PAHs. The analysis based on positive matrix factorization (PMF) indicated two sources of PM 2.5 of similar strength - burning vehicle fuels and biomass burning for residential heating. Levoglucosan originated exclusively from biomass burning, while 90% of elemental carbon was from vehicle emissions. About 62% of organic carbon, 85% of benzo(a)anthracene and 55-65% of the remaining PAHs originated from biomass burning. Compared to many worldwide locations, PM 2.5 , organic carbon, elemental carbon, and levoglucosan in Podkowa were among the lowest. The benzo(a)pyrene concentrations were the highest, while other PAHs were intermediate. However, the mass fractions of PAHs in Podkowa PM 2.5 were the highest among the four locations available for comparison. That may indicate the low quality of fuel-burning processes. PAH-related inhalation cancer risk based on PAH carcinogenic potency in Podkowa appeared marginal. This work aims to induce local administrative actions to improve air quality in garden towns.