Variations of atmospheric PAHs concentrations, sources, health risk, and direct medical costs of lung cancer around the Bohai Sea under the background of pollution prevention and control in China

Abstract. The Bohai Sea (BS) as the most polluted area of PAHs in China has been received wide attention in recent decades. To characterize the variations of concentrations and sources of PAHs from June 2014 to May 2019, fifteen congeners of PAHs (∑₁₅PAHs) were measured from atmospheric samples (N=228) collected at 12 sites around the BS, and health risk and direct medical costs associated with lung cancer exposed to PAHs were also estimated. The annual daily average concentration of ∑₁₅PAHs was 56.8 ± 4.7 ng m^-3, dominated by low molecular weight (LMW-PAHs, 3-ring) (58.9 ± 7.8 %). During the five-year sampling period, the atmospheric ∑₁₅PAHs concentration reduced by 17.5 % for the whole BS, especially in the tightly controlled area of Tianjin (TJ) with a drop of 51.7 %, which was mainly due to the decrease of high molec-ular weight PAHs (HMW-PAHs, 5-6 ring) concentration. Generally, the concentration of ∑₁₅PAHs was highest in winter and lowest in summer, mainly attributed to the change of LMW-PAHs concentration. Based on PMF model, PAHs at the BS were mainly ascribed to coal combustion and biomass burning. And the contribution of coal combustion and motor vehicle to PAHs had a different performance between the BS (coal combustion rose by 6.7 %, motor vehi-cle fell by 22.7 %) and TJ (coal combustion fell by 13.2 %, motor vehicle rose by 6.7 %). The in-cidence of lung cancer (ILCR) caused by exposing to atmospheric PAHs at the BS and TJ de-creased by 74.1 % and 91.6 % from 2014 to 2018, respectively. That was mainly due to the de-crease of the concentration of highly toxic HMW-PAHs. It was reflected on the savings of $10.7 million in direct medical costs of lung cancer exposed PAHs, which was accounted 46.1 % before air prevention and control around the BS. And there was a higher cost reduction of 54.5 % in TJ. Hence, this study proved that implementing pollution prevention and control not only effective-ly reduced the concentration of pollutants and the caused risks, but also significantly reduced the medical costs of diseases caused by corresponding expose.