Factor analysis of recent variations of atmospheric polycyclic aromatic hydrocarbons (PAHs) and 1-nitropyrene (1-NP) in Shenyang, China from 2014 to 2020

Abstract

Shenyang is the provincial capital of Liaoning province in China, and the high population and heavy machinery manufacturing cause severe air pollution. Nine polycyclic aromatic hydrocarbons (PAHs) and 1-nitropyrene (1-NP) were characterized in aerosol samples collected in Shenyang in summer and winter from 2014 to 2020. The mean annual concentration of PAHs and 1-NP decreased from 102 to 18.7 ng/m3 and 105 to 61.3 pg/m3, respectively, from 2014 to 2020. The change from coal to electric and natural gas heating, transition from small coal-heating stoves to large stoves and vehicle and fuel upgrades resulted in decreases in atmospheric PAH and 1-NP concentrations. The noteworthy finding in this study was that the proportion of 4-ring PAHs increased in summer but decreased in winter from 2014 to 2020 in Shenyang. Possible factors were considered that a higher cetane rating of fuel with a new standard reduced emissions in summer, higher combustion temperatures of large coal-heating stoves and use of air pollution control devices in winter. In contrast, although the health risks of PAHs and 1-NP in Shenyang significantly decreased from 2014 to 2020, the values are still higher than the national standards in the winter of 2020. Additional environmental regulations in Shenyang are urgently needed to further decrease PAH concentrations below national air quality standards.