Atmos. Chem. Phys., 20, 14581–14595, 2020 https://doi.org/10.5194/acp-20-14581-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Nationwide increase of polycyclic aromatic hydrocarbons in ultrafine particles during winter over China revealed by size-segregated measurements Qingqing Yu1, Xiang Ding1,4, Quanfu He1, Weiqiang Yang5, Ming Zhu1,2, Sheng Li1,2, Runqi Zhang1,2, Ruqin Shen1, Yanli Zhang1,3,4, Xinhui Bi1,4, Yuesi Wang3,6, Ping’an Peng1,4, and Xinming Wang1,2,3,4 1State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 2University of Chinese Academy of Sciences, Beijing 100049, China 3Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China 4Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China 5Guangdong Provincial Academy of Environmental Science, Guangzhou 510045, China 6State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China Correspondence: Xinming Wang ([email protected]), and Xiang Ding ([email protected]) Received: 10 June 2020 – Discussion started: 22 June 2020 Revised: 13 October 2020 – Accepted: 14 October 2020 – Published: 1 December 2020 3 Abstract. Polycyclic aromatic hydrocarbons (PAHs) are BaPeq (8.48 vs. 1.34 ng/m / and PAHs’ inhalation cancer risk toxic compounds in the atmosphere and have adverse effects (7.4 × 10−4 vs. 1.2 × 10−4/. Nationwide increases in both on public health, especially through the inhalation of partic- PAH levels and inhalation cancer risk occurred in winter. The ulate matter (PM). At present, there is limited understand- unfavorable meteorological conditions and enhanced emis- ing of the size distribution of particulate-bound PAHs and sions of coal combustion and biomass burning together led their health risks on a continental scale. In this study, we to severe PAHs’ pollution and high cancer risk in the at- carried out a PM campaign from October 2012 to Septem- mosphere of northern China, especially during winter. Coal ber 2013 at 12 sampling sites simultaneously, including ur- combustion is the major source of BaPeq in all size particles ban, suburban and remote sites in different regions of China. at most sampling sites. Our results suggested that the reduc- Size-segregated PAHs and typical tracers of coal combus- tion of coal and biofuel consumption in the residential sector tion (picene), biomass burning (levoglucosan) and vehicle could be crucial and effective in lowering PAH concentra- exhaust (hopanes) were measured. The annual averages of tions and their inhalation cancer risk in China. P the 24 total measured PAHs ( 24PAHs) and benzo[a]pyrene (BaP) carcinogenic equivalent concentration (BaPeq/ ranged from 7.56 to 205 ng/m3 with a mean of 53.5 ng/m3 and from 0.21 to 22.2 ng/m3 with a mean of 5.02 ng/m3, respectively. 1 Introduction P At all the sites, 24PAHs and BaPeq were dominant in the ultrafine particles with aerodynamic diameter < 1.1 µm, Ambient particulate matter (PM) pollution has adverse ef- followed by those in the size ranges of 1.1–3.3 µm and fects on public health. The global deaths caused by expo- > 3.3 µm. Compared with southern China, northern China sure to PM with aerodynamic diameters less than 2.5 µm P 3 witnessed much higher 24PAHs (87.36 vs. 17.56 ng/m /, (PM2:5/ kept increasing from 1990 and reached 4.2 million in 2015 (Cohen et al., 2017). In China, ambient PM2:5 pol- Published by Copernicus Publications on behalf of the European Geosciences Union. 14582 Q. Yu et al.: Nationwide increase of PAHs in ultrafine particles during winter lution was ranked the fourth leading risk of death (Yang et China (Zhang et al., 2009). In addition, through long-range al., 2013) and caused 1.7 million premature deaths in 2015 atmospheric transport, PAHs emitted in China could spread (Song et al., 2017). Adverse health impacts of PM are asso- to other regions of the world (Zhang et al., 2011; Inomata et ciated with particle size and chemical components (Chung et al., 2012). al., 2015; Dong et al., 2018). A higher risk of cardiovascular For more accurate estimation of inhalation exposure to disease was associated with smaller size-fractionated partic- ambient PAHs and their cancer risk in China, it is essential ulate matter, especially PM1:0-bound particulate matter (Yin to carry out nationwide campaigns to acquire spatial and sea- et al., 2020). sonal characteristics of atmospheric PAHs. Data on PAHs in Polycyclic aromatic hydrocarbons (PAHs) are a group of the ambient air have accumulated in China during the past organic substances composed of two or more aromatic rings. decades. Among these field studies, most were conducted Due to their mutagenic, teratogenic and carcinogenic proper- in rapidly developing economic regions, including the North ties (Kim et al., 2013), PAHs are one of the most toxic com- China region (Huang et al., 2006; Liu et al., 2007; Wang et ponents in PM (Xu et al., 2008). Toxic PAHs usually enrich al., 2011; Lin et al., 2015a; Lin et al., 2015b; Tang et al., in fine particles, especially those with aerodynamic diame- 2017; Yu et al., 2018), Yangtze River Delta region (Liu et al., ters less than 1.0 µm (Wang et al., 2016; Li et al., 2019), 2001; Zhu et al., 2009; Gu et al., 2010; He et al., 2014) and which can enter the human respiratory system through in- Pearl River Delta region (Bi et al., 2003; Guo et al., 2003; halation (Yu et al., 2015). Exposure to PAHs likely induces Li et al., 2006; Tan et al., 2006; Duan et al., 2007; Lang et DNA damage and raises the risk of genetic mutation (Zhang al., 2007; Yang et al., 2010; Gao et al., 2011, 2012, 2013, et al., 2012; Lv et al., 2016) and cardiopulmonary mortality 2015; Yu et al., 2016), due to large amounts of combustion (Kuo et al., 2003; John et al., 2009). Previous studies have emission and the high density of population in these regions. demonstrated that inhalation exposure to PAHs can cause a These studies provided insight into the fate and health risk of high risk of lung cancer (Armstrong et al., 2004; Zhang et al., airborne PAHs on a local or regional scale. However, due to 2009; Shrivastava et al., 2017). inconsistency in sampling methods, frequency and duration Atmospheric PAHs are mainly emitted from the incom- in these local and regional campaigns, it is difficult to draw a plete combustion of fossil fuels and biomasses (Mastral and national picture of PAHs’ pollution in the air of China. Callen, 2000). As typical semi-volatile chemicals, PAHs can There are rare datasets discovering nationwide character- be transported over long distances (Zelenyuk et al., 2012) istics of airborne PAHs over China. Liu et al. (2007b) re- and have been detected in the global atmosphere (Brown et ported PAHs in the air of 37 cities across China using pas- al., 2013; Garrido et al., 2014; Hong et al., 2016; B. Liu et sive polyurethane foam (PUF) disks. Wang et al. (2006) and al., 2017; Hayakawa et al., 2018). An emission inventory in- D. Liu et al. (2017) determined PM2:5-bound PAHs over 14 dicated that developing countries are the major contributors and 9 Chinese cities, respectively. PAHs in total suspended to global PAHs’ emission (Zhang and Tao, 2009; Shen et particles (TSPs) and the gas phase were measured over 11 al., 2013a). cities in China (Ma et al., 2018, 2020). In addition to this As the largest developing country in the world, China has important information on PAHs in the bulk PM, it is vital to large amounts of PAHs’ emission and high cancer risk caused determine the size distribution of PAHs, since the size of par- by exposure to PAHs. The annual emission of 16 US EPA pri- ticles is directly linked to their potential to cause health prob- ority PAHs in China sharply increased from 18 Gg in 1980 to lems. On the national scale, at present, there is only one field 106 Gg in 2007 (Xu et al., 2006; Shen et al., 2013a). China study available reporting size-segregated atmospheric PAHs became the largest emitter of PAHs, accounting for about at 10 sites (Shen et al., 2019). Therefore, it is essential to 20 % of the global PAHs’ emission during 2007 (Shen et carry out large-range campaigns covering multiple types of al., 2013a). The excess lung cancer risk caused by inhalation sites across different regions to investigate the size distribu- exposure to ambient PAHs was estimated to be 6.5 × 10−6 tion of PAHs’ levels and sources and discover their difference in China (Zhang et al., 2009), which was 5.5 times higher in health risks among typical regions of China (e.g. north than the acceptable risk level of 1.0 × 10−6 in the United vs. south, urban vs. remote). In this study, we simultaneously States (US EPA, 1991). As Hong et al. (2016) estimated, collected filter-based size-fractionated PM samples consecu- the lifetime excess lung cancer cases caused by exposure to tively at 12 sites for 1 year. We analyzed chemical composi- PAHs for China ranged from 27.8 to 2200 per million peo- tions of PAHs as well as other organic tracers to characterize ple and were higher than other Asian countries. Moreover, the spatiotemporal pattern and size distribution of PAHs over PAHs’ emission and cancer risk in China have large spatial China and to explore the possible sources of PAHs on the na- and seasonal variations.