https://api.elsevier.com/content/article/pii/S0269749121009428doi:10.1016/j.envpol.2021.1173601-s2.0-S026974912100942810.1016/j.envpol.2021.117360S0269-7491(21)00942-8Polycyclic aromatic hydrocarbons and nitro-polycyclic aromatic hydrocarbons in five East Asian cities: Seasonal characteristics, health risks, and yearly variations Environmental PollutionJournal026974912021-10-1515 October 20210falsefalse