Indoor/outdoor Characterization,sources And Health Risks Of PAHs And Their Derivatives In Typical Rural Areas Of China

Polycyclic aromatic hydrocarbons(PAHs),as a persistent organic pollutant,are widely present in the atmosphere,water,soil and other environments.They have strong carcinogenic,teratogenic,and mutagenic properties,threatening human health.Nitro-and oxygenated polycyclic aromatic hydrocarbons(NPAHs,OPAHs)are the more common polycyclic aromatic hydrocarbon derivatives in the environment,and their toxicity is much higher than that of PAHs.On average,people spend nearly 90%of their time indoors.Excessive pollutants in the indoor air will directly threaten human health.In addition,indoor dust is also an important carrier of various pollutants.The human body can be exposed to harmful pollutants in dust through skin contact and other means.There are frequent indoor solid fuel combustion activities in rural areas in China.In order to study the pollution of indoor and outdoor PAHs and their derivatives in different rural areas,indoor and outdoor air samples were collected in rural households in Gansu,Shanxi,Shandong,Jilin,Henan and Anhui Province using PUF passive air samplers from May to July 2019 and November 2019 to January 2020.The corresponding dust samples were collected at the same time.The indoor/outdoor concentration,composition characteristics,indoor and outdoor relationships,sources,and health risks of PAHs,NPAHs and OPAHs in air and dust were analyzed in rural households.The highest concentrations of PAHs,NPAHs and OPAHs were found in kitchen air,and higher concentrations were found in winter.The concentrations of PAHs,NPAHs and OPAHs in dust were both higher than those in the outdoor,and the seasonal differences in concentrations were relatively small.On the whole,heavier indoor pollution of PAHs and their derivatives was found in northern rural households that use coal and biomass fuels.There was little difference in the composition of PAHs and their derivatives at different sampling points.In the air,PAHs were all dominated by LMW-PAHs such as FLU and PHE at different sampling points,NPAHs were dominated by 1N-NAP and 2N-NAP,and the highest proportion of OPAHs was 1-NALD.The substance with larger molecular weight were dominant in dust.Among PAHs,high content of FLT and CHR were found in dust at all sampling points,the dominant component of NPAHs were 1N-PYR,9N-ANT and 2+3N-FLT,and OPAHs had the highest proportion of ATQ.The indoor and outdoor concentration ratios(I/O)of PAHs in air and dust showed that PAHs mainly came from indoor sources both in indoor air and dust.Indoor PAHs had more significant indoor sources in northern areas where biomass was the main fuel.The distribution of I/O ratios of OPAHs and OPAHs was more complicated.In summer,indoor NPAHs and OPAHs were mainly from indoor sources at all sampling points.They were more susceptible to outdoor sources in winter,but still had a significant indoor source in Qingyang.The characteristic ratio method was used to analyze the possible sources of indoor and outdoor PAHs and NPAHs in the study area.The results showed that PAHs in air and dust mainly came from coal,biomass and liquid fossil fuels combustion,and the fuels combustion sources were more significant in winter.PAHs were affected by petroleum sources in air of Changzhi and Xuchang sampling points.NPAHs in indoor air of each sampling point mainly came from the primary emission of fuel combustion.In outdoor air,NPAHs mainly came from the primary emission sources in Qingyang,Dunhua and Changzhi sampling points,but were from secondary generation in Anqing,Qingdao and Xuchang.NPAHs in indoor and outdoor dust were mainly from the primary emission of fuel combustion activities at each sampling point.Incremental lifetime cancer risk(ILCR)was used to assess the risk of children and adults exposure to PAHs and NPAHs in indoor and outdoor air and dust in rural aeras.The total exposure risk of rural indoor PAHs and NPAHs were much higher than that of outdoor.And it was found that the total carcinogenic risk of children were higher than that of adults which mainly because children had a higher exposure risk from oral intake of PAHs and NPAHs in dust.Northern rural residents who used biomass and coal as the main fuel had a higher total carcinogenic risk when they exposed to indoor and outdoor PAHs and NPAHs.In this study,simultaneous research on the pollution of PAHs and their derivatives in indoor air and dust is of great significance for comprehensive assessment of indoor environmental pollution in rural areas.The data obtained provides a theoretical basis for the prevention and control of indoor PAHs and their derivatives in rural areas in China.