Investigation into atmospheric PM2.5-borne PAHs in Eastern cities of China: concentration, source diagnosis and health risk assessment

hsa_circ_0008500 regulates Benzo(a)pyrene-loaded gypsum-induced inflammation and apoptosis in human bronchial epithelial cells via activation of Ahr/C-myc pathways

Polycyclic aromatic hydrocarbons (PAHs) are major organic pollutants attached to fine particulate matter in the atmosphere. They induce lung inflammation, asthma, and other lung diseases. Exploring the toxic mechanism of PAHs on lung epithelial cells may provide a theoretical basis for the prevention and treatment of respiratory diseases induced by PAHs. In our study, 16 human bronchial epithelial (16HBE) cells were exposed to different concentrations of gypsum dust, Benzo(a)pyrene (BaP), and BaP-loaded gypsum dust for 24 hours. Gypsum dust loaded with BaP significantly increased the cytotoxicity of 16HBE cells, enhanced the production of lactate dehydrogenase (LDH), interleukin-6 (IL-6) and interleukin-8 (IL-8), induced cell apoptosis, and upregulate the expression of hsa_circ_0008500 (circ_0008500). The mechanism was studied with a BaP-loaded gypsum dust concentration of 1.25 mg/mL. StemRegenin 1 (SR1) pretreat significantly reduced the release of LDH, IL-6, and IL-8 and decreased the protein levels of Ahr、XAP2, C-myc, and p53. Second-generation sequencing indicated that circ_0008500 was highly expressed after 16HBE induced by BaP-loaded gypsum dust. Functional experiments confirmed that circ_0008500 promoted the inflammation and apoptosis of 16HBE cells induced by BaP-loaded gypsum dust by regulating the Ahr signaling pathway. Our study showed that fine particulate matter adsorption of BaP significantly increased the toxic effect of BaP on cells. By activating the Ahr/C-myc pathway, circ_0008500 promoted inflammation and apoptosis of 16HBE cells induced by BaP-loaded gypsum dust.

Characterization and health risk assessment of PM2.5-bound polycyclic aromatic hydrocarbons in Yangon and Mandalay of Myanmar

To better understand the potential adverse health effects of atmospheric fine particles in the Southeast Asian developing countries, PM2.5 samples were collected at two urban sites in Yangon and Mandalay, representing coastal and inland cities in Myanmar, in winter and summer during 2016 and 2017. The concentrations of 21 polycyclic aromatic hydrocarbons (PAHs) in PM2.5 were determined using a gas chromatography-mass spectrometry (GC-MS). The concentrations of PAHs in PM2.5 in Yangon and Mandalay ranged from 7.6 to 180 ng m-3, with an average of 72 ng m-3. The PAHs were significantly higher in winter than in summer, and significantly higher in Mandalay than in Yangon. The health risk analysis of PAHs, based on the toxic equivalent quantity (TEQ) calculation, and the incremental lifetime cancer risk (ILCR) assessment indicated that PM2.5 in Myanmar has significant health risks with higher health risks in Mandalay compared to Yangon. Diagnostic ratios of PAHs, correlation of PAHs with other species in PM2.5 and the positive matrix factorization (PMF) analysis showed that TEQ is strongly affected by biomass burning and vehicular emissions in Myanmar. Additionally, it was found that the aging degree of aerosols and air mass trajectories had great influences on the concentration and composition of PAHs in PM2.5 in Myanmar, thereby affecting the toxicity of PM2.5.

Alterations in sperm DNA methylation may as a mediator of paternal air pollution exposure and offspring birth outcomes: Insight from a birth cohort study

Paternal exposure to environmental risk factors influences the offspring health. This study aimed to evaluate the association between paternal air pollution exposure mediated by sperm DNA methylation and adverse birth outcomes in offspring. We recruited 1607 fertile men and their partners from 2014 to 2016 and collected semen samples to detect sperm DNA methylation. Multivariate linear regression and weighted quantile sum regression models were used to assess the associations between paternal air pollution exposure and offspring birth outcomes. A critical exposure window was identified. Reduced representation bisulfite sequencing was used to detect sperm DNA methylation. The results demonstrated that high paternal exposure to PM2.5 (β = -211.31, 95% CI: (-386.37, -36.24)), PM10 (β = -178.20, 95% CI: (-277.13, -79.27)), and NO2 (β = -84.22, 95% CI: (-165.86, -2.57)) was negatively associated with offspring's birthweight, especially in boys. Additionally, an early exposure window of 15-69 days before fertilization was recognized to be the key exposure window, which increased the risk of low birth weight and small for gestational age. Furthermore, paternal co-exposure to six air pollutants contributed to lower birthweight (β = -51.91, 95% CI: (-92.72, -11.10)) and shorter gestational age (β = -1.72, 95% CI: (-3.26, -0.17)) and PM2.5 was the most weighted pollutant. Paternal air pollution exposure resulted in 10,328 differentially methylated regions and the IGF2R gene was the key gene involved in the epigenetic process. These differentially methylated genes were predominantly associated with protein binding, transcriptional regulation, and DNA templating. These findings indicate that spermatogenesis is a susceptible window during which paternal exposure to air pollution affects sperm DNA methylation and the birth outcomes of offspring.

Exposure and health risk assessment of PM2.5-bound polycyclic aromatic hydrocarbons during winter at residential homes: A case study in four Chinese cities

Residential indoor PM2.5 were concurrently collected in Hong Kong, Guangzhou, Shanghai, and Xi'an during the winter and early spring seasons of 2016-2017, for updating the current knowledge of the spatial variation of indoor air pollution and the potential health risks in China. PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) were characterized, and the associated inhalation cancer risks were assessed by a probabilistic approach. Higher levels of indoor PAHs were identified in Xi'an residences (averaged at 176.27 ng m-3) with those of other cities ranging from 3.07 to 15.85 ng m-3. Traffic-related fuel combustion was identified as a common contributor to indoor PAHs through outdoor infiltration for all investigated cities. Indoor PAHs profiles showed city-specific differences, while distinctions between profiles based on indoor activities or ambient air quality were limited. Similar with the total PAHs concentrations, the estimated toxic equivalencies (TEQ) with reference to benzo[a]pyrene in Xi'an residences (median at 18.05 ng m-3) were above the recommended value of 1 ng m-3 and were magnitudes higher than the other investigated cities with estimated median TEQ ranging from 0.27 to 1.55 ng m-3. Incremental lifetime cancer risk (ILCR) due to PAHs inhalation exposure was identified with a descending order of adult (median at 8.42 × 10-8) > adolescent (2.77 × 10-8) > children (2.20 × 10-8) > senior (1.72 × 10-8) for different age groups. Considering the lifetime exposure-associated cancer risk (LCR), potential risks were identified for residents in Xi'an as an LCR level over 1 × 10-6 was identified for half of the adolescent group (median at 8.96 × 10-7), and exceedances were identified for about 90 % of the groups of adults (10th percentile at 8.29 × 10-7) and seniors (10th percentile at 1.02 × 10-6). The associated LCR estimated for other cities were relatively insignificant.

Genomic Characterization Revealed PM2.5-Associated Mutational Signatures in Lung Cancer Including Activation of APOBEC3B

Fine particulate matter (PM_2.5) exposure causes DNA mutations and abnormal gene expression leading to lung cancer, but the detailed mechanisms remain unknown. Here, analysis of genomic and transcriptomic changes upon a PM_2.5 exposure-induced human bronchial epithelial cell-based malignant transformed cell model in vitro showed that PM_2.5 exposure led to APOBEC mutational signatures and transcriptional activation of APOBEC3B along with other potential oncogenes. Moreover, by analyzing mutational profiles of 1117 non-small cell lung cancers (NSCLCs) from patients across four different geographic regions, we observed a significantly higher prevalence of APOBEC mutational signatures in non-smoking NSCLCs than smoking in the Chinese cohorts, but this difference was not observed in TCGA or Singapore cohorts. We further validated this association by showing that the PM_2.5 exposure-induced transcriptional pattern was significantly enriched in Chinese NSCLC patients compared with other geographic regions. Finally, our results showed that PM_2.5 exposure activated the DNA damage repair pathway. Overall, here we report a previously uncharacterized association between PM_2.5 and APOBEC activation, revealing a potential molecular mechanism of PM_2.5 exposure and lung cancer.

Health risk assessment of inorganic and organic constituents of the coarse and fine PM in an industrialized region of Brazil

A health risk assessment of inorganic and organic species associated with coarse and fine particulate matter (PM) was conducted in Southeastern Brazil. TSP, PM₁₀, and PM_2.5 samples were collected, and their elemental (metals/metalloids) and organic (PAHs) composition were determined by EDXRF and GC-MS. The health risks were determined through hazard quotient (HQ) and cancer risk (CR). It was found that different elements and routes of exposure lead to different health risks, even for the PM concentration in compliance with air quality standards. The major routes of exposure for adults were inhalation and dermal contact whereas for children were ingestion and dermal contact. High non-cancer risks (HQ) caused by Cl and Fe exposure were associated with coarser fractions, PM₁₀ and TSP, respectively, whereas high HQ for Se, Sb, and V exposure were associated with PM_2.5. HQ values for children were near twice that for adults, and CR values were 65 % to 130 % higher for children than for adults. CR posed by PAHs was negligible. The results highlighted that the HQ might be over- or underestimated depending on the form in which the element Cl is determined (elemental or ion), reinforcing the need for an embracing chemical characterization of the PM. High HQ values were found related to the exposure to some elements present in the TSP, showing that this PM fraction should not be neglected.

Polycyclic aromatic hydrocarbons in urban particle matter exacerbate movement disorder after ischemic stroke via potentiation of neuroinflammation

BACKGROUND

A recent epidemiological study showed that air pollution is closely involved in the prognosis of ischemic stroke. We and others have reported that microglial activation in ischemic stroke plays an important role in neuronal damage. In this study, we investigated the effects of urban aerosol exposure on neuroinflammation and the prognosis of ischemic stroke using a mouse photothrombotic model.

RESULTS

When mice were intranasally exposed to CRM28, urban aerosols collected in Beijing, China, for 7 days, microglial activation was observed in the olfactory bulb and cerebral cortex. Mice exposed to CRM28 showed increased microglial activity and exacerbation of movement disorder after ischemic stroke induction. Administration of core particles stripped of attached chemicals from CRM28 by washing showed less microglial activation and suppression of movement disorder compared with CRM28-treated groups. CRM28 exposure did not affect the prognosis of ischemic stroke in null mice for aryl hydrocarbon receptor, a polycyclic aromatic hydrocarbon (PAH) receptor. Exposure to PM2.5 collected at Yokohama, Japan also exacerbated movement disorder after ischemic stroke.

CONCLUSION

Particle matter in the air is involved in neuroinflammation and aggravation of the prognosis of ischemic stroke; furthermore, PAHs in the particle matter could be responsible for the prognosis exacerbation.

The deposition mapping of polycyclic aromatic hydrocarbons in megacity Shanghai, China

The deposition of polycyclic aromatic hydrocarbon (PAHs) has far-reaching impacts on Earth's surface system and human health. However, a comprehensive understanding of PAHs' deposition in a high urbanized area is still lacking because of limited field measurements data and rough resolution of current models. In this research, a deposition map of PAHs with a resolution of 2 × 2 km in megacity Shanghai, China was established. Gridded annual total deposition of PAHs from July 2020 to June 2021 ranged from 385 to 10,631 ng/(m²·d), with a mean value of 2,611 ng/(m²·d). The highest PAHs deposition was found over the downtown Shanghai, which received 4.3 times the deposition flux of outlying areas. About 77 % of area in Shanghai was dominated by wet deposition which accounted for 62 % of total deposition in Shanghai. The total deposition showed a trend of summer>fall>spring>winter, which was similar to that of the amount of rain. Source apportionment and geographically weighted regression analysis showed that built-up land and human activities are key driving factors of PAHs' deposition in Shanghai. Our results suggest that intensive human activities could alter the PAHs deposition distribution in Shanghai, and improve the understanding of PAHs' environmental behavior in high urbanized area.

Effects of polycyclic aromatic hydrocarbon exposure on mitochondrial DNA copy number

Airborne polycyclic aromatic hydrocarbon (PAH) exposure can adversely affect human health by generating reactive oxygen species (ROS) and increasing oxidative stress, which causes changes in mitochondrial DNA copy number (mtDNAcn), a key indicator of mitochondrial damage and dysfunction. This study aimed to determine the effects of atmospheric benzo[a]pyrene (BaP) and 1-nitropyrene (1-NP) exposure on mtDNAcn in humans. One hundred and eight adults living in Cheongju, South Korea, were included in this study. Atmospheric BaP and 1-NP concentrations and urinary 6-hydroxy-1-nitropyrene (6-OHNP), N-acetyl-1-aminopyrene (1-NAAP), and 1-hydroxypyrene concentrations were measured. Blood samples were also collected to assess mtDNAcn. The mean mtDNAcn was 9.74 (SD 4.46). mtDNAcn decreased significantly with age but was not significantly associated with sex, sampling season, or smoking habit. While there was a borderline significant increase in mtDNAcn with increasing ambient total PAH levels, ambient PAH or urinary 1-hydroxypyrene concentrations showed no significant association with mtDNAcn. However, urinary 6-OHNP or 1-NAAP concentrations, 1-NP metabolites, were significantly associated with mtDNAcn. These results suggest that the metabolism of absorbed NPs generates excess ROS, which damages mitochondrial DNA, resulting in increased mtDNAcn.

Cancer risk assessment and source apportionment of the gas- and particulate-phase of the polycyclic aromatic hydrocarbons in a metropolitan region in Brazil

A risk assessment and a source apportionment of the particulate- and gas-phase PAHs were conducted in a high vehicular traffic and industrialized region in southeastern Brazil. Higher concentrations of PAHs were found during summer, being likely driven by the contributions of PAHs in the vapor phase caused by fire outbreaks during this period. Isomer ratio diagnostic and Principal Component Analysis (PCA) identified four potential sources in the region, in which the Positive Matrix Factorization (PMF) model confirmed and apportioned as gasoline-related (31.8%), diesel-related (25.1%), biomass burning (23.4%), and mixed sources (19.6%). The overall cancer risk had a tolerable value, with ∑CR = 4.6 × 10^-5, being ingestion the major via of exposure (64% of the ∑CR), followed by dermal contact (33% of the ∑CR) and inhalation (3%). Mixed sources contributed up to 45% of the overall cancer risk (∑CR), followed by gasoline-related (up to 35%), diesel-related (up to 15%), and biomass burning (up to 10%). The risk assessment for individual PAH species allowed identifying higher CR associated with BaP, DBA, BbF, BaA, and BkF, species associated with gasoline-related and industrial sources. Higher risks were associated with PM_2.5-bound PAHs exposure, mainly via ingestion and dermal contact, highlighting the need for measures of mitigation and control of PM_2.5 in the region.

Joint effects of polycyclic aromatic hydrocarbons, smoking, and XPC polymorphisms on damage in exon 2 of KRAS gene among young coke oven workers

Genetic polymorphisms may contribute to individual susceptibility to DNA damage induced by environmental exposure. In this study, we evaluate the effects of co-exposure to PAHs, smoking and XPC polymorphisms, alone or combined, on damage in exons. A total of 288 healthy male coke oven workers were enrolled into this study, and urinary 1-hydroxypyrene (1-OH-Pyr) was detected. Base modification in exons of KRAS and BRAF gene, and polymorphisms of XPC were determined in plasma by real-time PCR. We observed 1-OH-Pyr was positively related to damage in exon 2 of KRAS (KRAS-2) and in exon 15 of BRAF (BRAF-15), respectively, and KRAS-2 and BRAF-15 were significantly associated with increased 1-OH-Pyr. A stratified analysis found 1-OH-Pyr was significantly associated with KRAS-2 in both smokers and non-smokers, while 1-OH-Pyr was significantly associated with BRAF-15 only in smokers. Additionally, individuals carrying both rs2228001 G-allele (GG+GT) and rs3731055 GG homozygote (GG) genotype appeared to have more significant effect on KRAS-2. The high levels of 1-OH-Pyr were associated with KRAS-2 only in rs2228001 GG+GT genotype carriers and the high levels of 1-OH-Pyr were associated with KRAS-2 only in rs3731055 GG genotype carriers and the most severe KRAS-2 was observed among subjects carrying all four of the above risk factors. Our findings indicated the co-exposure effect of PAHs and smoking could increase the risk of KRAS-2 by a mechanism partly involving XPC polymorphisms.

Health Risk Assessment on Exposure to PM2.5-bound PAHs from an Urban-industrial Area in Rayong City, Thailand

BACKGROUND: A city's industrial area's air quality has become a major priority. PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) are one of the most common pollutants in urban-industrial area, and can be linked to health problems. AIM: This study aims to 1) investigate PM2.5 and PAHs emitted from roadside area (RS) and industrial estate (IE) in Rayong city 2) assess the inhalation of PM2.5 and PAHs on the human health of the age group. METHODS: PM2.5-bound PAHs were investigated and thier carcinogenic risk was evalued in this study. PM2.5 samples were collected on quartz filters contained in a mini-volume air sampler and analyzed for PAHs by GC-MS. RESULTS: The average PM2.5 concentrations at RS and IE were 43.3±26.8 and 40.4±21.7 µg/m3, while the values of total PAHs in both sites were 1.68±1.53 and 1.34±1.22 ng/m3, respectively. However, it was found that the PM2.5 and PAHs values were not significantly different (p>0.05). The results revealed that the individual lifetime cancer risk (Ric) of PM2.5 values for children and adults at both sites indicated acceptable cancer risk (10-6 to10-4). According to the incremental lifetime cancer risk (ILCR) values of PAHs for different age groups, exposure to PAHs in PM2.5 through the inhalation pathway was a negligible (<10-6). CONCLUSION: As a result, the PM2.5 concentrations have substantial implications for Rayong city’s environmental management and protection, relating to car emissions and coal combustion.

Health risks of PM2.5-bound polycyclic aromatic hydrocarbon (PAH) and heavy metals (PPAH&HM) during the replacement of central heating with urban natural gas in Tianjin, China

To investigate the health effects of fine particulate matter (≤ 2.5 μm in aerodynamic diameter; PM_2.5)-bound heavy metals and polycyclic aromatic hydrocarbons (PAHs) before and after the implementation of the Urban Natural Gas Heating Project (UNGHP), the lifetime cancer risks, hazard quotients (HQs) of heavy metals and PAHs were calculated. Seven kinds of heavy metals (Al, As, Cd, Cr, Mn, Ni and Se) and 12 kinds of PAHs including acenaphthylene (ANY), acenaphthene (ANA), fluoranthene (FLT), pyrene (PYR), chrysene (CHR), benz[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), dibenz[a,h]anthracene (DBA), benzo[ghi]perylene (BPE) and indeno[1,2,3-cd]pyrene (IPY) were analyzed and used for the health risk assessments. It was found that HQ of Mn fell from 1.09 in the coal-burning period to 0.72 in the gas-burning period in the suburban area. And lifetime cancer risks of PAHs fell from 35.7 × 10^-6 in the coal-burning period to 17.22 × 10^-6 in the gas-burning period in the urban area. It could be concluded that, during the gas-burning period, downward trends were observed for the lifetime cancer risks and HQs of most kinds of heavy metals and PAHs in all regions of Tianjin compared to those during the coal-burning period. The UNGHP was effective, and we should also take other measures to control the pollution.

Determination of tipping point in course of PM2.5 organic extracts-induced malignant transformation by dynamic network biomarkers

The dynamic network biomarkers (DNBs) are designed to identify the tipping point and specific molecules in initiation of PM_2.5-induced lung cancers. To discover early-warning signals, we analyzed time-series gene expression datasets over a course of PM_2.5 organic extraction-induced human bronchial epithelial (HBE) cell transformation (0^th~16^th week). A composition index of DNB (CI_DNB) was calculated to determine correlations and fluctuations in molecule clusters at each timepoint. We identified a group of genes with the highest CI_DNB at the 10^th week, implicating a tipping point and corresponding DNBs. Functional experiments revealed that manipulating respective DNB genes at the tipping point led to remarkable changes in malignant phenotypes, including four promoters (GAB2, NCF1, MMP25, LAPTM5) and three suppressors (BATF2, DOK3, DAP3). Notably, co-altered expression of seven core DNB genes resulted in an enhanced activity of malignant transformation compared to effects of single-gene manipulation. Perturbation of pathways (EMT, HMGB1, STAT3, NF-κB, PTEN) appeared in HBE cells at the tipping point. The core DNB genes were involved in regulating lung cancer cell growth and associated with poor survival, indicating their synergistic effects in initiation and development of lung cancers. These findings provided novel insights into the mechanism of dynamic networks attributable to PM_2.5-induced cell transformation.

Platelet Mitochondrial DNA Methylation as Epigenetic Biomarker of Short-Term Air Pollution Exposure in Healthy Subjects

Air pollution exposure is now considered a growing concern for global public health. RNA or DNA methylation changes caused by air pollution may be related to the development of cardiovascular disease. To investigate the early biomarkers of air pollution exposure, a panel study of eight college students recorded after a business trip from Qingdao to Shijiazhuang and back to Qingdao was performed in this work. The concentration of PM_2.5, PM₁₀, SO₂, NO₂, and CO in Shijiazhuang was higher than that in Qingdao during the study period. The platelet count was positively correlated with air pollutants of 0–6 day moving averages (β_PM2.5 = 88.90; β_PM10 = 61.83; β_SO2 = 41.13; β_NO2 = 57.70; β_CO = 62.99, respectively, for an IQR increased). Additionally, internal dose biomarkers 2-OHNa, 1-OHNa, 2-OHFlu, 2,3-OHPhe, and ∑PAHs were also significantly associated with platelet count in participants. Furthermore, PM_2.5 and PM₁₀ are positively linked with methylation of one CpG site at platelet mitochondrial gene CO2 (PM_2.5 = 0.47; PM₁₀ = 0.25, respectively, for an IQR increase). Both platelet counts and methylation levels returned to their pre-exposure levels after leaving the highly contaminated area. In short, this study investigated the relationship between platelet properties and air pollution exposure, revealing that short-term exposure to air pollution might increase the risk of thrombosis. Our research suggests that platelet count and mitochondrial DNA methylation of mtCO2 site 2 in platelets from healthy adults may be the novel biomarker for acute exposure to air pollution.

Human health risks estimations from polycyclic aromatic hydrocarbons in serum and their hydroxylated metabolites in paired urine samples

Polycyclic aromatic hydrocarbons (PAHs) are compounds with two or more benzene rings whose hydroxylated metabolites (OH-PAHs) are excreted in urine. Human PAH exposure is therefore commonly estimated based on urinary OH-PAH concentrations. However, no study has compared PAH exposure estimates based on urinary OH-PAHs to measurements of PAH levels in blood samples. Estimates of PAH exposure based solely on urinary OH-PAHs may thus be subject to substantial error. To test this hypothesis, paired measurements of parent PAHs in serum and OH-PAHs in urine samples from 480 participants in Guangzhou, a typical developed city in southern China, were used to investigate differences in the estimates of human PAH exposure obtained by sampling different biological matrices. The median PAH concentration in serum was 4.05 ng mL^-1, which was lower than that of OH-PAHs in urine (8.33 ng mL^-1). However, serum pyrene levels were significantly higher than urinary levels of its metabolite 1-hydroxypyrene. Concentrations of parent PAHs in serum were not significantly correlated with those of their metabolites in urine with the exception of phenanthrene, which exhibited a significant negative correlation. Over 28% of the participants had carcinogenic risk values above the acceptable cancer risk level of 10^-6. Overall, estimated human exposure and health risks based on urinary 1-hydroxypyrene levels were only 13.6% of those based on serum pyrene measurements, indicating that estimates based solely on urine sampling may substantially understate health risks due to PAH exposure.

Polycyclic aromatic hydrocarbon contamination along roads based on levels on vehicle window films

Vehicular emissions are known to be major contributors of airborne polycyclic aromatic hydrocarbons (PAHs) in cities. In order to assess the long-term contamination of PAHs along roads, we collected organic films from vehicle windows (26 private cars and 4 buses, in Shanghai, China) and used mathematical models to convert the film-bound PAH concentrations to the airborne PAH concentrations. The field measurements of airborne PAHs revealed that the partitioning and Level III fugacity model was suitable to estimate the airborne concentrations of high and low volatile PAHs (expect for naphthalene), respectively. The total airborne PAH concentrations along roads in Shanghai ranged from 0.83 to 3.37 μg m^-3 and the incremental lifetime cancer risks (ILCR_total) by exposure to PAHs along roads were greater than the USEPA lower guideline of 10^-6, indicating non-negligible carcinogenic risks to drivers and passengers, especially via ingestion processes. This study provided a practicable method to investigate long-term air contamination of PAHs in vehicles and along roads based on film-bound PAH on vehicle windows. In addition, it was also possible to investigate the health risk in vehicles as a result of exposure to PAHs. Comparisons of PAHs between roads and shipping lanes also facilitated the delineation of vehicular and shipping PAH inventories. A capsule that summarizes the main finding of the work: Investigating film-bound PAH on vehicle windows is a practicable pathway to investigate the long-term contamination of PAHs in vehicles and along roads. This method can not only simplify the sampling processes, but the model calculations. The results also enabled investigations into ILCR in vehicles and specified source apportionment of traffic PAHs.

Geographical distribution of polycyclic aromatic hydrocarbons in estuarine sediments over China: Human impacts and source apportionment

Human activity is suggested to increase polycyclic aromatic hydrocarbons (PAHs) pollution and also cause PAHs' sources complex in estuarine environments. However, the human impacts and source apportionment of PAHs in estuarine sediments at a continental scale remains poorly understood. In this study, we investigated geographical distribution of PAHs and used the compound-specific carbon isotope approach to characterize the sources of PAHs in the sediments of estuaries along the latitudinal gradient over China. We also used human population and economic size to characterize the human impacts on PAHs pollution in the estuaries. The concentrations of total PAHs (Σ₁₆ PAH) in wet and dry seasons ranged from 60.9 to 330.7 ng g^-1 and from 103.9 to 620.6 ng g^-1, respectively, across the estuaries. At the continental scale, the concentrations of PAHs were significantly higher in dry than in wet seasons. The proportions of low molecular weight (LMW, 2-3 ring PAHs), middle molecular weight (MMW, 4 ring PAH) and high molecular weight (HMW, 5-6 ring PAHs) of PAHs varied largely across the estuaries, with being in a range of 26.4-48.5%, 17.2-34.1%, 25.3-46.8% in wet season and in a range of 24.0-58.4%, 18.4-52.4%, 21.8-48.6% in dry season. The concentrations of PAHs were found to be significantly correlated with per capita GDP throughout the studied estuaries. The δ¹³C of individual PAH ranged from -26 to -32‰ and from -24 to -29‰ in dry and wet seasons, respectively. The main sources of PAHs indicated by the δ¹³C across the estuaries were coal-processing and biomass combustion. These results suggest that the increasing human activities intensity can increase the PAHs pollution in sediments of the estuaries.

Characteristics and Health Risk Assessment of PM2.5-Bound PAHs during Heavy Air Pollution Episodes in Winter in Urban Area of Beijing, China

PM2.5 level has decreased significantly in Beijing in recent years due to the strict air quality control measures taken in Jingjinji Region and the surrounding areas. However, the variation characteristics of the concentrations of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) in Beijing in recent years are still not so clear. In order to understand the pollution status of PM2.5-bound PAHs in Beijing, fifteen PAHs were measured in a typical urban area of Beijing from 1 March to 20 March 2018. The average mass concentration of the 15 PAHs was 21 ng/m3 and higher in the nighttime than that in the daytime. The proportion of 4-ring PAHs in 15 PAHs was highest (43%), while 6-ring PAHs was lowest (10%). The levels of PAHs were higher during heavy pollution episodes than those in non-heavy pollution episodes, and the proportions of 5- and 6-ring PAHs were increased during a heavy pollution episode. PAHs posed obvious carcinogenic risks to the exposed populations, and the risk was higher during heavy pollution episodes than the average value of the whole monitoring period. The main sources of PAHs were traffic emissions and coal/biomass burning. Air masses from the south-southeast had a great influence on the PM2.5 levels during a heavy pollution episode. It is recommended that not only the PM2.5 levels but also the PAHs levels bounded in PM2.5 should be controlled to protect human health in Beijing.

The impact of heating season factors on eight PM2.5-bound polycyclic aromatic hydrocarbon (PAH) concentrations and cancer risk in Beijing

In 2015, 443 atmospheric PM_2.5 samples were collected at five sampling sites in Beijing. The concentrations of PM_2.5-bound PAH₈ (Chr, BaA, BbF, BkF, B[a]P, DBA, BghiP, and IND) were determined via high performance liquid chromatography (HPLC). The annual concentration of PM_2.5-bound PAH₈, lifetime cancer risk, and the increasing value due to heating season factors (heating and meteorological conditions) were analyzed. The results showed that the sum concentration of PM_2.5-bound PAH₈ during heating season was 72.6 ng/m³ and higher than the non-heating season concentration of 4.77 ng/m³. The annual concentration was 10.6 ng/m³, which increased 5.83 ng/m³ due to heating season factors. The B[a]P annual concentration was 1.67 ng/m³ and higher than the limit of 1 ng/m³, which was 15.2 times that of non-heating season. Diesel vehicles and gasoline vehicles were the primary PAH₈ sources during non-heating season, while the mixed sources of diesel vehicles, gasoline vehicles, and combustion were the dominant PAH₈ sources during heating season. The most significant health hazard pollutant was B[a]P, which accounted for 72%, 74%, and 69% of the B[a]P equivalent concentration (B[a]Peq) of PAH₈ during heating season, non-heating season, and throughout 2015, respectively. The lifetime cancer risk was 2.67 × 10^-6, which increased 1.36 × 10^-6 due to heating season factors. Therefore, heating season factors nearly doubled the annual concentration of PM_2.5-bound ∑PAH₈ and lifetime cancer risk. The results indicated that to protect human health, it is very important to control PM_2.5-bound ∑PAH₈ emissions during heating season, especially B[a]P emissions.

Pollution Characterization and Source Apportionment of Day and Night PM2.5 Samples in Urban and Suburban Communities of Tianjin (China)

Day and night PM_2.5 samples were collected from two typical urban and suburban communities in Tianjin. The major chemical components in PM_2.5, including the metal elements, polycyclic aromatic hydrocarbons (PAHs), and inorganic water-soluble ions, were monitored. A positive matrix factorization (PMF) model was used to apportion the potential sources of PM_2.5 at the two sites in the daytime and nighttime. The results indicated that the PM_2.5 concentration was higher in the suburban area than in the urban area during the daytime in winter. The daytime and nighttime PAHs concentrations at both sites were both generally higher in winter than in summer. The concentrations of some of the metal elements were higher in summer than in winter. Regional differences and day and night differences in the metals and water-soluble ions commonly existed. The PMF analysis indicated that coal combustion and transportation-related sources were the predominant sources in the urban and suburban areas in the daytime in winter, and secondary aerosols were the most important source for the suburban area in the nighttime in winter. There were more pollution sources of PM_2.5 during the daytime in summer, especially in the suburban area. In the nighttime in summer, the pollution sources of PM_2.5 in the urban and suburbs areas were basically the same, but the source apportionment was quite different.

Characteristics, sources and health risk assessment of airborne particulate PAHs in Chinese cities: A review

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds composed of at least two benzene rings. This paper reviews the characteristics, sources and health risk of airborne particulate PAHs in Chinese cities. The airborne particulate PAH concentrations varied from 3.35 to 910 ng m^-3, with an average of 75.0 ng m^-3, and the pollution level of PAHs in northern cities was generally higher than that in southern cities. The PAH concentrations in different cities underwent similar seasonal variations, with high concentrations in the winter and relatively low concentrations in the summer. Many factors, such as meteorological conditions and source emissions, influenced the spatiotemporal pattern of PAHs. High temperatures, frequent flow exchanges, abundant rainfall and strong solar radiation reduced the level of particulate PAHs in the atmosphere. The historical changes in the level of airborne particulate PAHs in four cities were analyzed. The PAH concentrations in Beijing and Taiyuan presented a trend of first increasing and then decreasing, while the level of particulate PAHs in Nanjing and Guangzhou had a decreasing tendency from year 2000-2015. The airborne particulate PAHs in cities were derived from several sources, including coal combustion, vehicle emissions, coking industries, biomass burning and petroleum volatilization. The results of a health risk assessment indicated that the incremental lifetime cancer risk (ILCR) for people in the northern cities was higher than that for people in the other regions, especially during the cold season. Moreover, adults were at greater risk than people in other age groups, and the health risk to females was slightly higher than that to males. The potential risk of airborne particulate PAH exposure was relatively high in some cities, and controlling PAH emissions at the source should be required to prevent pollution.

A multimedia fugacity model to estimate the fate and transport of polycyclic aromatic hydrocarbons (PAHs) in a largely urbanized area, Shanghai, China

Increasing PAHs pollution is creating more complex urban pollution system. However, the availability of sufficient monitoring activities for PAHs in multicompartment and corresponding multi-interface migration processes is still not well understood. In this study, a Level III steady state fugacity model was validated to evaluate the detailed local variations, and mass fluxes of PAHs in various environmental compartments (i.e., air, soil, sediment, water, vegetation and organic film). This model was applied to a region of Shanghai in 2012 based on a large number of measured data and brings model predictions in 2020. The model results indicate that most of the simulated concentrations agreed with the observed values within one order of magnitude with a tendency of underestimation for vegetation. Direct emission is the main input pathway of PAHs entering the atmosphere, whereas advection is the main outward flow from Shanghai. Organic film was achieved the highest concentration of PAHs compared to other compartments up to 58.17 g/m³. The soil and sediment served as the greatest sinks of PAHs and have the longest retention time (2421.95-78642.09 h). Importantly, a decreasing trend of PAHs was observed in multimedia from 2012 to 2020 and the transfer flux from the air to vegetation to soil was the dominant pathways of BaP intermedia circulation processes. A sensitivity analysis showed that temperature was the most influential parameter, especially for Phe. A Monte Carlo simulation emphasized heavier PAHs were overpredicted in film and sediment, but lighter PAHs in air and water were generally underestimated.

An overview of research and development themes in the measurement and occurrences of polyaromatic hydrocarbons in dusts and particulates

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds consisting of two or more fused aromatic rings and are probably one of the most studied groups of organic chemicals in environmental research. PAHs originate mainly from anthropogenic processes, particularly from incomplete combustion of organic fuels. PAHs are distributed widely in particulate matter. Due to widespread sources and persistent characteristics, PAHs disperse through atmospheric transport and exist almost everywhere. Human beings are exposed to PAH mixtures in gaseous or particulate phases in ambient air. Long-term exposure to high concentrations of PAHs is associated with adverse health problems. This review identifies the main research and development themes in the measurement and occurrences of PAHs in dusts and particulates using a new approach to carrying out a literature review where many peer-review publications have been produced. The review extracts the most important research themes from a literature search using a combination of text mining and a more detailed review of selected papers from within the identified themes.

Concentration characteristics, source apportionment, and oxidative damage of PM2.5-bound PAHs in petrochemical region in Xinjiang, NW China

Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their potential as human carcinogens. Thus, determining the characteristics, potential source, and examining the oxidative capacity of PAHs to protect human health is essential. This study investigated the PM_2.5-bound PAHs at Dushanzi, a large petrochemical region in Xinjiang as well as northwest China. A total of 33 PM_2.5 samples with 13 PAHs, together with molecular tracers (levoglucosan, and element carbon), were analyzed during the non-heating and heating periods. The results showed that the PM_2.5 concentrations were 70.22 ± 22.30 and 95.47 ± 61.73 μg/m³, while that of total PAHs were 4.07 ± 2.03 and 60.33 ± 30.80 ng/m³ in sampling period, respectively. The fluoranthene, pyrene, chrysene, benzo[b]fluoranthene, and benzo[k]fluoranthene were the most abundant (top five) PAHs, accounting for 71.74 and 72.80% of total PAH mass during non-heating and heating periods. The BaP equivalent (BaPeq) concentration exceeded 1 ng/m³ as recommended by National Ambient Air Quality Standards during heating period. The diagnostic ratios and positive matrix factorization indicated that oil industry, biomass burning, coal combustion, and vehicle emissions are the primary sources. The coal combustion remarkably increased during heating period. The plasmid scission assay (PSA) results showed that higher DNA damage rate was observed during heating period. PAHs in PM_2.5 such as Chr, BaP, and IcdP were found to have significantly positive correlations with the plasmid DNA damage rates. Additionally, the relationship among BaPeq and DNA damage rate suggested that synergistic reaction may modify the toxicity of PAHs.

Trends in analytical techniques applied to particulate matter characterization: A critical review of fundaments and applications

Epidemiological studies have shown the association of airborne particulate matter (PM) size and chemical composition with health problems affecting the cardiorespiratory and central nervous systems. PM also act as cloud condensation nuclei (CNN) or ice nuclei (IN), taking part in the clouds formation process, and therefore can impact the climate. There are several works using different analytical techniques in PM chemical and physical characterization to supply information to source apportionment models that help environmental agencies to assess damages accountability. Despite the numerous analytical techniques described in the literature available for PM characterization, laboratories are normally limited to the in-house available techniques, which raises the question if a given technique is suitable for the purpose of a specific experimental work. The aim of this work consists of summarizing the main available technologies for PM characterization, serving as a guide for readers to find the most appropriate technique(s) for their investigation. Elemental analysis techniques like atomic spectrometry based and X-ray based techniques, organic and carbonaceous techniques and surface analysis techniques are discussed, illustrating their main features as well as their advantages and drawbacks. We also discuss the trends in analytical techniques used over the last two decades. The choice among all techniques is a function of a number of parameters such as: the relevant particles physical properties, sampling and measuring time, access to available facilities and the costs associated to equipment acquisition, among other considerations. An analytical guide map is presented as a guideline for choosing the most appropriated technique for a given analytical information required.

PM2.5-bound PAHs in three indoor and one outdoor air in Beijing: Concentration, source and health risk assessment

Three indoor (residential home, dormitory, and office) and one outdoor concentrations of PM_2.5-bound Polycyclic aromatic hydrocarbons (PAHs) were analyzed in Beijing across four seasons. The highest and lowest concentration of total PAHs for outdoor appeared in winter and in summer with averages of 200.1 and 9.1ng/m³ respectively. The seasonal variations of total PAHs in three indoor sites were the same as outdoor. The correlation analysis between the indoor and outdoor samples showed that the annual mean I/O ratios of total PAHs in the three sites were lower than 1. Source apportionment showed vehicle exhaust, coal combustion, and biomass burning were the major contributors of indoor and outdoor PM_2.5-bound PAHs. Indoor source, such as camphor pollution, was identified in the dormitory, while camphor pollution and cooking sources were identified in the residential home. The annual averages of Benzo[a]pyrene equivalent concentration (BaP_eq) were 7.6, 7.8, 7.7 and 12.7ng/m³ for the dormitory, office, residential home and outdoor samples respectively, far higher than the annual limit of 1ng/m³ regulated by European Commission. Life lung cancer risk (LLCR) in four sites across four seasons were over the acceptable cancer risk level, showing the cancer risk were at a high level in both indoor and outdoor sites in Beijing, and its level in indoor sites was much lower than in the outdoor site. The health risk assessment indicated the level of PAHs cancer risk on human for three indoor sites were similar. The results call for the development of more stringent control measures to reduce PAHs emissions.