Atmospheric PM2.5 samples from Wuhan, China were collected during a winter period of February and a summer period of August in 2018. The average PM2.5 mass concentration in winter reached 112 μg/m3—about two-fold higher than that found in summer. Eight ionic species constituted 1/3 of PM2.5, whereas more than 85% represented secondary ionic aerosols (NO3−, SO42− and NH4+). Higher ratios of NO3−/SO42− (0.95–2.62) occurred in winter and lower ratios (0.11–0.42) occurred in summer showing the different contribution for mobile and stationary sources. Seventeen elemental species constituted about 10% of PM2.5, with over 95% Na, Mg, Al, Ca, Fe, K and Zn. Higher K-concentration occurred in winter indicating greater contribution from biomass and firework-burning. Carcinogenic risks by Cr, As, Cd, Ni and Pb in PM2.5 indicated that about 6.94 children and 46.5 adults among per million may risk getting cancer via inhalation during surrounding winter atmospheric sampling, while about 5.41 children and 36.6 adults have the same risk during summer. Enrichment factors (EFs) and elemental ratios showed that these hazardous elements were mainly from anthropogenic sources like coal and oil combustion, gasoline and diesel vehicles.

The size-segregated distribution and seasonal concentrations of polycyclic aromatic hydrocarbons (PAHs) in urban suspended particulate matter (SPM) at the Japan national route 463 in the urban of Saitama city, Japan were investigated using an Andersen high-volume air sampler. Air sampling was carried out from June 2013 to January 2014. 37 species of toxic PAHs such as benzo [j] [a,l]pyrene were measured. It was found that the average concentration of 37 species of particulate PAHs including methyl-PAHs, benzothiophenes and oxy-PAHs from atmospheric oxidation of PAHs collected in the urban of Saitama city was 3.42 to 6.51 ng/m 3 during 2013 sampling campaign periods. 1,8-naphthalic anhydride (1,8-NA) showed the highest concentration among 37 species of PAHs. The concentrations of high molecular PAHs, which were found in all seasons, followed different size distribution, especially with the highest peak in fine particle sizes around 1.1 μm. The concentrations of low-molecular PAHs were not much different with particle sizes. The toxicity analysis indicated that the carcinogenic potency of particulate PAHs primarily existed in the particle size below 1.1 μm. 37 species of PAHs in urban atmospheric fine particles were not only derived from vehicle emission with long range transportation, but also produced by local other anthropogenic sources.