Seasonal distribution of PM2.5-bound polycyclic aromatic hydrocarbons as a critical indicator of air quality and health impact in a coastal-urban region of Poland

Abstract

This study focuses on the inter-seasonal distribution and variability of thirteen native PAHs adsorbed onto respirable PM2.5 fraction collected in a coastal-urban region of northern Poland, in 2019. The backward trajectory analysis and several diagnostic ratios were applied to determine seasonal profiles of PAH congeners and their major sources in airborne samples. The annual cumulative mean value of total PAHs in PM2.5 was 6.92 ± 10.1 ng m−3, varying in the following range: 0.32 ng m−3 (May) – 68.57 ng m−3 (January). Seasonal mass concentrations of total particulate PAHs were ranked as follows: summer (1.27 ng m−3) < spring (4.83 ng m−3) < autumn (6.16 ng m−3) < winter (18.5 ng m−3). Clear seasonal differences in PAH concentrations can be explained by direct impact of local and regional urban/industrial activities, with priority winter contribution of coal combustion in residential and commercial sectors. In addition, for summer measurements the diagnostic ratios indicated that high molecular weight PAHs were mainly derived from vehicle emission and petrochemical industry, while relatively low mass contribution of 4-ring congeners to the total sum of PAHs was attributed to photochemical processing. The analysis of meteorological parameters (temperature, relative humidity) and gaseous precursors (SO2, NO2, NOx, O3 and CO) exhibits their statistically significant correlations with PAHs, indicating local/regional primary emission. The incremental lifetime cancer risk was 1.23 × 10−5, suggesting potential toxicity and carcinogenicity for adult females and males. This study highlights the importance of the implementation of health risk assessment model in urbanized coastal zones.