Hydrocarbons In PM2 Research Articles

Coal and biomass combustion emissions increase the cancer and health risks of polycyclic aromatic hydrocarbons in PM2.5 from Nanchang, central China

This study collected 365 daily PM2.5 samples from Nanchang City and analysed the characteristics, sources, and risks of polycyclic aromatic hydrocarbons (PAHs). The findings indicated that the yearly average ΣPAH concentration (the sum of 15 PAHs) was 7.20 ± 4.52 ng m−3, with the highest concentration in winter (12.24 ± 4.95 ng m−3), followed by autumn (7.05 ± 3.1 ng m−3), spring (5.85 ± 2.47 ng m−3) and summer (3.76 ± 1.72 ng m−3). The molecular characteristics and diagnostic ratios analysis suggested that the PAHs originated from vehicle exhaust, combustion (coal and biomass), and petroleum volatilisation. The results of quantitative estimation showed that vehicle exhaust and combustion sources contributed the most (about 43% and 40%) to PAHs. The petroleum industry accounted for a smaller proportion, approximately 17%. Seasonally, combustion sources (coal and biomass) contributed more in winter (56%) and autumn (51%), whereas vehicle exhaust contributed more in summer (51%) and spring (54%). High atmospheric pressure inhibited the diffusion of PAHs but high temperatures may have promoted PAH decomposition. The results of the risk assessment showed that Nanchang residents exposed to PAHs face a potentially low carcinogenic risk but a definite non-carcinogenic health risk during autumn and winter. Furthermore, adults had greater cancer and health risks compared to children. During autumn and winter, it is probable that combustion emissions were the primary contributing factor to risks of PAHs.

Emissions of polycyclic aromatic hydrocarbons in PM2.5 emitted from motor vehicles exhaust (PAHs-PM2.5-MVE) under the plateau with low oxygen content

Emissions of PAHs and their derivatives from motor vehicles exhaust are mainly due to inadequate combustion of fossil fuels, the combustion efficiency of engine is lower under the plateau with low oxygen content, which will exacerbate the emission of pollutants, especially organic substance. In order to investigate the emission of PAHs-PM2.5-MVE under the plateau with low oxygen content, tunnel experiments and bench tests were conducted in a typical plateau region in Yunnan Province. The study indicated the concentrations of PAHs-PM2.5-MVE in the tunnels of Caohai and Xidu reached 548.11 ± 307.12 and 1241.19 ± 197.54 ng/m3, respectively. The emission factor of PAHs-PM2.5-MVE in the Caohai Tunnel was estimated to be 438.61 ± 296.86 μg/veh/km, and that for gasoline and diesel vehicles in bench tests were 442.83 ± 82.57 and 4098.04 ± 551.21 μg/kg fuel. Meanwhile, the emission factors of carbonaceous component, CO and PAHs-PM2.5-MVE were at a high level that were higher than those in plain which due to the inadequate combustion of fuels in engine. A probabilistic risk assessment framework was integrated to quantitatively estimate the exposure risk for the population of the tunnels, the HPAHs-PM2.5-MVE had potential carcinogenic risk. The study can improve our understanding of the influence of organic substance from inadequate combustion of fuels on the environment and human.

Probing the occurrence, sources and cancer risk assessment of polycyclic aromatic hydrocarbons in PM2.5 in a humid metropolitan city in China.

Fifty-two consecutive PM2.5 samples from December 2021 to February 2022 (the whole winter) were collected in the center of Chongqing, a humid metropolitan city in China. These samples were analysed for the 16 USEPA priority polycyclic aromatic hydrocarbons (16 PAHs) to explore their composition and sources, and to assess their cancer risks to humans. The total concentrations of the 16 PAHs (ng m-3) ranged from 16.45 to 174.15, with an average of 59.35 ± 21.45. Positive matrix factorization (PMF) indicated that traffic emissions were the major source (42.4%), followed by coal combustion/industrial emission (31.3%) and petroleum leakage/evaporation (26.3%). The contribution from traffic emission to the 16 PAHs increased from 40.0% in the non-episode days to as high as 46.2% in the air quality episode during the sampling period. The population attributable fraction (PAF) indicates that when the unit relative risk (URR) is 4.49, the number of lung cancer cases per million individuals under PAH exposure is 27 for adults and 38 for seniors, respectively. It was 5 for adults and 7 for seniors, when the URR is 1.3. The average incremental lifetime cancer risk (ILCR) for children, adolescents, adults and seniors was 0.25 × 10-6, 0.23 × 10-6, 0.71 × 10-6, and 1.26 × 10-6, respectively. The results of these two models complemented each other well, and both implied acceptable PAH exposure levels. Individual genetic susceptibility and exposure time were identified as the most sensitive parameters. The selection and use of parameters in risk assessment should be further deepened in subsequent studies to enhance the reliability of the assessment results.

Assessing anthropogenic contribution to PM2.5 from an urban residential area of Lagos, Nigeria using aliphatic hydrocarbon compounds as indicators

Aliphatic hydrocarbons in PM2.5 samples from a residential area of Lagos, Nigeria, were quantified using a Curie-point pyrolysis–gas chromatography–mass spectroscopy (CPPGC/MS). The total concentrations of ∑n-alkanes (C20-C34), hopanes (∑4Hopanes), and steranes (∑3Steranes) ranged from 1.8 to 146.6 ng m-3 (avg. 43.6 ± 35.1 ng m-3), 0.0 to 89.9 ng m-3 (avg. 18.7 ± 25.9 ng m-3), and 0.0 to 26.0 ng m-3 (avg. 3.3 ± 6.7 ng m-3), accounting for 0.2%, 0.1%, and 0.01% of the total PM2.5 mass concentrations, respectively. They also accounted for, 1%, 0.4% and 0.1% of the organic matter content, respectively, making them non-negligible component of the organic matter in this region. An evaluation of the n-alkanes source diagnostic indices revealed that engines powered by gasoline and diesel were the main sources of particulate matter aliphatic hydrocarbons in this area of Lagos, consistent with the results obtained from steranes and hopanes profiles. Based on the air mass trajectories, both local and regional air mass transports showed a significant influence on the amounts of carbonaceous materials and aliphatic hydrocarbon compounds arriving at the study site. The results from this study established the occurrence of anthropogenic air pollution in Lagos residential area with a major contribution from petrogenic sources.

Characterization and Source Apportionment of Polycyclic Aromatic Hydrocarbons in PM2.5 in Lanzhou

To study the pollution characteristics and sources of 16 PAHs in PM2.5 in Lanzhou, PM2.5 samples were collected in four seasons. GC-MS was employed to analyze the concentration of PAHs. Positive matrix factorization(PMF), trajectory cluster, and potential source contribution function(PSCF) were used to identify the sources of PAHs. The results indicated that the average concentration of PAHs in PM2.5 in Lanzhou decreased in the order of winter[(118±16.2) ng·m-3]>autumn[(50.8±21.6) ng·m-3]>spring[(22.2±8.87) ng·m-3]>summer[(4.65±1.32) ng·m-3]. The results of correlation analysis showed that PM2.5 and TPAHs in Lanzhou had an extremely significant negative correlation with temperature; an extremely significant positive correlation with atmospheric pressure; and a poor correlation with wind direction, wind speed, and relative humidity. The proportion of PAHs with 4-5 rings was much higher than that of those with 6 rings and 2-3 rings, with similar results across the four seasons. Source apportionment results illustrated that the contribution of industrial emissions and biomass and natural gas combustion were dominant in spring and summer seasons. Industrial emissions and coal combustion were dominant in autumn and winter, respectively. The vehicle emissions had no significant change across the four seasons. Trajectory cluster and PSCF analyses showed that the airflow coming from Mongolia, northeast Xinjiang, and Qinghai had important effects on the ambient air quality in Lanzhou.

Temporal and spatial distributions, source identification, and health risk assessment of polycyclic aromatic hydrocarbons in PM2.5 from 2016 to 2021 in Shenzhen, China.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in the atmosphere that have drawn intense attention due to their carcinogenicity and mutagenicity. In this work, 1424 air samples were collected between January 2016 and December 2021 in three areas of Shenzhen, China to determine the concentrations of PM2.5 and PAHs and their spatiotemporal variation. Human health risks due to the daily intake and uptake of PAHs and the resulting incremental lifetime cancer risk (ILCR) were also evaluated. PAHs were detected frequently in the samples at concentrations between 0.28 and 32.7ng/m3 (median: 1.04ng/m3). PM2.5 and PAH concentrations decreased from 2016 to 2021, and the Yantian area had lower median concentrations of PM2.5 (23.0μg/m3) and PAHs (0.02ng/m3) than the Longgang and Nanshan areas. The concentrations of PM2.5 and PAHs were significantly higher in winter than in summer. Analysis of diagnostic ratios indicated that petroleum combustion was the dominant source of airborne PAHs in Shenzhen. The estimated daily intake (EDI) and uptake (EDU) of PAHs by local residents decreased gradually with increasing age, indicating that infants are at particular risk of PAH exposure. However, the incremental lifetime cancer risks (ILCRs) were below the threshold value of 10-6, indicating that inhalation exposure to PAHs posed a negligible carcinogenic risk to Shenzhen residents. While promising, these results may underestimate actual PAH exposure levels, so further analysis of health risks due to PAHs in Shenzhen is needed.

Characterization of the sources and health risks of polycyclic aromatic hydrocarbons in PM2.5 and their relationship with black carbon: A case study in northern Taiwan

Polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) often coexist in PM2.5 because both form during the incomplete combustion of organic matter. These compounds are regarded as hazardous air pollutants with potential health effects, including respiratory and cardiovascular effects. In this study, to evaluate the health risks of PAHs and BC at an urban site in northern Taiwan, 16 priority PAHs and BC, identified by the United States Environmental Protection Agency, were analyzed and quantified in PM2.5 to determine their concentrations, their relationship with each other, and their likely sources. The results indicated that the mean concentrations of total PAHs and BC were 0.91 ng m−3 and 0.97 μg m−3, respectively, with a significant positive correlation between them, indicating the same emission sources. The results also indicated that fossil fuel combustion and traffic emissions were primary contributors to PAHs, with wood and biomass combustion playing a less prominent role. Among these 16 priority PAHs, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[b]fluoranthene, and indeno[1,2,3-cd]pyrene served as major carcinogenic compounds, accounting for 89.0% of the total carcinogenic toxicity. Thus, the lifetime excess cancer risk resulting from PAH exposure was estimated as 8.03 × 10−6, indicating a potential carcinogenic risk to human health at the sampling site. Overall, this study highlights the need for future mitigation policies for traffic emissions and fossil fuel combustion for reducing the local emissions of BC and co-produced PAHs in northern Taiwan.

Characteristics, sources and health risk assessment of trace metals and polycyclic aromatic hydrocarbons in PM2.5 from Hefei, China.

Trace metals (TRs) and polycyclic aromatic hydrocarbons (PAHs) are major toxic components of fine particulate matter (PM2.5) and related to various health adverse outcomes. The study aims to get a better understanding of the contents, sources and risks of PM2.5-bounded TRs and PAHs in Hefei, China, during the period of 2019-2021. We collected 504 samples and measured twelve TRs and sixteen priority PAHs by inductively coupled plasma mass spectrometry and high-performance liquid chromatography. The annual mass concentrations of PM2.5 was fluctuated in the year of 2019-2021 at 50.95, 47.48 and 59.38μg/m3, with seasonal variations in rank order of winter > spring > autumn > summer. The median concentrations of PM2.5-bounded ƩTRs and ƩPAHs were also fluctuated, 132.85, 80.93 and 120.27ng/m3 for ƩTRs, 2.57, 5.85 and 2.97ng/m3 for ƩPAHs, in the year of 2019, 2020 and 2021, respectively. Seasonal variations of ƩTRs and ƩPAHs show the highest concentration in winter. Positive matrix factorization was used for identified pollution emission sources, and TRs mainly originated from coal combustion, traffic emission and fugitive dust, while PAHs stemmed from biomass, diesel, gasoline and coal combustion. Health risk assessment indicated that adults were more vulnerable than children, the carcinogenic risk assessment of As and Cr manifested a certain degree of cancer risk (1.0 × 10-6 < CR < 1.0 × 10-4) in adults group, and health risks of TRs were higher than PAHs in Hefei. These findings suggest that PM2.5-bounded TRs and PAHs should be considered when making emission control strategies for air pollution, and winter, combustion sources and adults should achieve more policy attention to decrease exposure risks in Hefei.

Comparison of characteristics and sources of water-soluble inorganic ions, trace elements, and polycyclic aromatic hydrocarbons in PM2.5 on polluted and normal days in Ulsan, South Korea

Comparison of characteristics and sources of water-soluble inorganic ions, trace elements, and polycyclic aromatic hydrocarbons in PM2.5 on polluted and normal days in Ulsan, South Korea

Effects of Pear Extracts on Microbiome and Immunocytokines to Alleviate Air Pollution-Related Respiratory Hypersensitivity.

Pears are ancient functional foods for modern times. Particularly, Korean pears (Pyrus pyrifolia cv.) have been used as folk medicine for respiratory diseases and have strong potential for the treatment of hazardous aerosol-related diseases. Thus, the effects of pear ethanol extracts on air pollution-related respiratory hypersensitivity were studied by toxicokinetics, pro-inflammatory cytokines, and microbiomics in preclinical and randomized double-blind clinical studies. The mild-asthma subjects, who lived in the same city, Seoul, Korea, were separated into the placebo and the treatment (pear extracts, as brix 55; arbutin 5.01 mg and chlorogenic acid 0.18 mg/3 mL per day) groups for 4 weeks (n = 20). As results, there were positive associations between urinary 2-naphthol (NT) or 1-hydroxypyrene (OHP), exposure biomarkers for polyaromatic hydrocarbons in PM2.5, and pro-inflammatory cytokines, interleukin (IL)-4 or IgE, respectively, in the human subjects. The pear extracts somewhat reduced 2-NT and 1-OHP levels. The proportions of fiber-degrading bacteria that stimulate growth of beneficial microflora for immune defense, that is, Bifidobacterium and Eubacterium, were significantly higher in the pear consuming group than in the placebo group. Moreover, pro-inflammatory cytokines, including IgE, IL-4, IL-5, and IL-13, were significantly suppressed by the pear extracts in the preclinical tests of the ovalbumin-induced asthma mice. Thus, we suggest that air pollution-related respiratory hypersensitivity can be alleviated by Korean pear extracts by modulation of microbiome and immunocytokines.

Abundance, Source Apportionment and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons and Nitro-Polycyclic Aromatic Hydrocarbons in PM2.5 in the Urban Atmosphere of Singapore

In this study, the levels of fine particulate matter (PM2.5), polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) in PM2.5 samples were determined from 2020 to 2021 in Singapore. For analysis convenience, the sampling period was classified according to two monsoon periods and the inter-monsoon period. Considering Singapore’s typically tropical monsoon climate, the four seasons were divided into the northeast monsoon season (NE), southwest monsoon season (SW), presouthwest monsoon season (PSW) and prenortheast monsoon season (PNE)). The PM2.5 concentration reached 17.1 ± 8.38 μg/m3, which was slightly higher than that in 2015, and the average PAH concentration continuously declined during the sampling period compared to that reported in previous studies in 2006 and 2015. This is the first report of NPAHs in Singapore indicating a concentration of 13.1 ± 10.7 pg/m3. The seasonal variation in the PAH and NPAH concentrations in PM2.5 did not obviously differ owing to the unique geographical location and almost uniform climate changes in Singapore. Diagnostic ratios revealed that PAHs and NPAHs mainly originated from local vehicle emissions during all seasons. 2-Nitropyrene (2-NP) and 2-nitrofluoranthene (2-NFR) in Singapore were mainly formed under the daytime OH-initiated reaction pathway. Combined with airmass backward trajectory analysis, the Indonesia air mass could have influenced Singapore’s air pollution levels in PSW. However, these survey results showed that no effect was found on the concentrations of PAHs and NPAHs in PM2.5 in Indonesia during SW because of Indonesia’s efforts in the environment. It is worth noting that air masses from southern China could impact the PAH and NPAH concentrations according to long-range transportation during the NE. The results of the total incremental lifetime cancer risk (ILCR) via three exposure routes (ingestion, inhalation and dermal absorption) for males and females during the four seasons indicated a low long-term potential carcinogenic risk, with values ranging from 10−10 to 10−7. This study systematically explains the latest pollution conditions, sources, and potential health risks in Singapore, and comprehensively analyses the impact of the tropical monsoon system on air pollution in Singapore, providing a new perspective on the transmission mechanism of global air pollution.

Polycyclic aromatic hydrocarbons in PM2.5 from an e-waste source site and a receptor site in Southern China: Atmospheric transport and process implications

Polycyclic aromatic hydrocarbons (PAHs) are potential contaminants released from informal electronic waste (e-waste) recycling. PAHs in PM2.5 collected at a rural e-waste (source) site and a background (receptor) site in Southern China were measured. Seasonal variations and regional transport of PAHs were investigated, and their sources and atmospheric processes were implied. The median concentrations of ∑18PAHs at the e-waste site (13.7 ng/m3) were one order of magnitude higher than those at the background site (median = 1.54 ng/m3), indicating the informal e-waste dismantling was a significant source. The seasonal variations of PAH concentrations at the two sites were similar, exhibiting noticeably unimodal distributions in winter, predominantly associated with the strengthened e-waste dismantling activities. Three molecular diagnostic ratios (MDRs) can be collectively used as potential markers of field informal e-waste burning sources. The dispersion model revealed that regional atmospheric transport from this e-waste site was a source of PAHs in the background air. Some MDRs significantly changed at the background site compared to the source site but could not be explained by the lifetime and/or gas-particle partition of the isomers. The differences complied with recent theories about the multiphase reactivity and evaporation of PAHs on aerosols. It was proposed that in warm and humid climates, the losses of PAHs from PM2.5 were dominated by their phase separation or diffusion, which was n-octanol/water partition coefficient (KOW) dependent. This hypothesis was further supported by data in the literature.

Inhalation Bioaccessibility of Polycyclic Aromatic Hydrocarbons in PM2.5 under Various Lung Environments: Implications for Air Pollution Control during Coronavirus Disease-19 Outbreak.

Global spread of coronavirus disease-19 (COVID-19) is placing an unprecedented pressure on the environment and health. In this study, a new perspective is proposed to assess the inhalation bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in PM2.5 for people with various lung health conditions. In vitro bioaccessibility (IVBA) was measured using modified epithelial lung fluids simulating the extracellular environment of patients with severe and mild lung inflammation. The average PAH IVBA in PM2.5 of 24.5 ± 4.52% under healthy conditions increased (p = 0.06) to 28.6 ± 3.17% and significantly (p < 0.05) to 32.3 ± 5.32% under mild and severe lung inflammation conditions. A mechanistic study showed that lung inflammation decreased the critical micelle concentrations of main pulmonary surfactants (i.e., from 67.8 (for dipalmitoyl phosphatidylcholine) and 53.3 mg/L (for bovine serum albumin) to 44.5 mg/L) and promoted the formation of micelles, which enhanced the solubilization and competitive desorption of PAHs from PM2.5 in the lung fluids. In addition, risk assessment considering different IVBA values suggested that PAH contamination levels in PM2.5, which were safe for healthy people, may not be acceptable for patients with lung inflammation. Because of the large number of COVID-19 infections, and the fact that some survivors of COVID-19 were observed to still show symptoms of interstitial lung inflammation, the finding here can provide important implications for both the scientific community and policy makers in addressing health risk and air pollution control during the COVID-19 outbreak.

Variations in traffic-related polycyclic aromatic hydrocarbons in PM2.5 in Kanazawa, Japan, after the implementation of a new vehicle emission regulation

A three-year sampling campaign was conducted at a roadside air pollution monitoring station in the urban area of Kanazawa, Japan. Due to a new emission regulation, PAHs levels decreased over the sampling campaign, exhibiting values of 706 ± 413 pg/m3 in 2017, 559 ± 384 pg/m3 in 2018, and 473 ± 234 pg/m3 in 2019. In each year, similar seasonal variations in PAHs levels were observed, with higher levels observed in winter and lower levels in summer. Among the PAHs isomer ratios, we observed that the ratio of benzo[b]fluoranthene (BbF) and benzo[k]fluoranthene (BkF), [BbF]/([BbF] + [BkF]), and the ratio of indeno[1,2,3-cd]pyrene (IDP) and benzo[ghi]perylene (BgPe), [IDP]/([BgPe] + [IDP]), showed stability over the sampling campaign and were less affected by the new emission regulation, seasonal variations, and regional characteristics. When using the combined ratio ranges of 0.66 - 0.80 ([BbF]/([BbF] + [BkF]) and 0.26-0.49 ([IDP]/([BgPe] + [IDP]), traffic emissions were clearly distinguished from other PAHs emission sources. Principal component analysis (PCA) and positive matrix factorization (PMF) were also performed to further analyse the characteristics of traffic-related PAHs. Overall, this study affirmed the effectiveness of the new emission regulation in the reduction of PAHs emissions and provided a combined range for identifying PAHs traffic emission sources.

Polycyclic aromatic hydrocarbons in PM2.5 in the metropolitan zone of Mexico Valley: Impact of air quality management programmes

Atmospheric fine particulate matter ≤2.5 μm (PM2.5) is the main driver of air pollution's burden of disease worldwide. Polycyclic aromatic hydrocarbons (PAHs) are part of PM2.5 and most of them are toxic to human health. In this study, the PAHs in PM2.5 around the Metropolitan Zone of Mexico Valley (MZMV), determined in 2016–2017, were compared against PAHs determined a decade ago in 2006. Decreases of 34 ± 9% in carcinogenic PAHs and 60 ± 7% in benzo[ghi]perylene were observed. This behaviour is consistent with the decreasing trend of primary Atmospheric Criteria Pollutants in the same period. PAHs reductions were observed despite increases in population, vehicle fleet and demand for fuel consumption. PAHs diagnostic ratios (DRs) identified stationary/area sources, and vehicular sources based on a pair of DRs and a range of DR values, rather than on individual values. Greater diversity of stationary and area sources in 2016–2017 was identified. Changes in DRs related to vehicular sources were observed over a decade, associated with improvements in gasoline vehicle technology and the use of better-quality fuels in recent years. Air quality management programs related to reducing pollutant concentrations mainly emitted by gasoline vehicles are discussed. However, future efforts on controlling the emissions from diesel combustion sources is suggested. Finally, a brief comparison of PAHs with other cities around the world is described.

Seasonality, atmospheric transport and inhalation risk assessment of polycyclic aromatic hydrocarbons in PM2.5 and PM10 from industrial belts of Odisha, India

This study is the first attempt to assess the presence of 16 priority polycyclic aromatic hydrocarbons (PAHs) enlisted by the US Environmental Protection Agency in PM2.5 and PM10 from industrial areas of Odisha State, India. During 2017-2018, bimonthly sampling of PM10 and PM2.5 was carried out for 24h in the industrial and mining areas of Jharsuguda and Angul in Odisha during the pre-monsoon, monsoon, and post monsoon seasons. Highest mean concentration of ∑16PAHs in PM2.5 was observed during the post monsoon (170ng/m3) period followed by pre-monsoon (48ng/m3) and monsoon (16ng/m 3) periods, respectively. A similar trend of ∑16PAHs was also observed in PM10 with higher levels observed during post monsoon (286ng/m3) followed by pre-monsoon (81ng/m3) and monsoon (27ng/m3) seasons. Diagnostic ratios and principal component analysis suggested diesel, gasoline and coal combustion as the major contributors of atmospheric PAH pollution in Odisha. Back trajectory analysis revealed that PAH concentration was affected majorly by air masses originating from the northwest direction traversing through central India. Toxic equivalents ranged between 0.24 and 94.13ng TEQ/m3. In our study, the incremental lifetime cancer risk ranged between 10-5 and 10-3, representing potential cancer risk.

Human health risk assessment for PAHs, phthalates, elements, PCDD/Fs, and DL-PCBs in PM2.5 and for NMVOCs in two East-Mediterranean urban sites under industrial influence

This study evaluates the carcinogenic and the non-carcinogenic health risks related to non-methane volatile organic compounds (NMVOCs) and elements, dioxins, furans, dioxin-like polychlorobiphenyls, phthalates and polycyclic aromatic hydrocarbons in PM2.5 samples collected during a one-year field campaign in two urban industrial areas in the East Mediterranean region. The health risk was assessed for the three exposure pathways (ingestion, inhalation and dermal contact) and for different age categories (newborns, children, adolescents, and adults). The non-carcinogenic risk calculated for the different species showed that benzene and n-heptane explained 78–94% of the total hazard index (HI) for NMVOCs at both sites. The total HI for NMVOCs varied between 2.9 and 26.8 at Zouk and between 0.8 and 6.6 at Fiaa for adults and newborns respectively exceeding the recommended USEPA limit of 1 for most age categories. PM2.5-bound elements had values higher than the recommended USEPA limit for newborns with Mn, Pb, V, and Ni as the major contributors. The other species under study presented moderate risk values. The lifetime cancer risk due only to the exposure to NMVOCs was 170 and 46 times higher than the threshold limit at Zouk and Fiaa, respectively. PM2.5-bound PAHs, As, Co, Cr(VI), Ni and V concentrations showed lifetime cancer risk exceeding the threshold limit of 10−6 with 58 and 28 additional cancer cases per million habitats at Zouk and Fiaa, respectively. To our knowledge, this assessment is a first evaluating the health risk of several classes of compounds from both particulate and gas phases.

Polycyclic aromatic hydrocarbons in PM2.5 atmospheric particles in Shiraz, a city in southwest Iran: sources and risk assessment

Polycyclic aromatic hydrocarbons in PM2.5 atmospheric particles in Shiraz, a city in southwest Iran: sources and risk assessment

Emission factors, characteristics, and gas-particle partitioning of polycyclic aromatic hydrocarbons in PM2.5 emitted for the typical solid fuel combustions in rural Guanzhong Plain, China

Solid fuel is a the most dominant energy source for household usages in developing countries. In this study, emission characteristics on organic carbon (OC), elemental carbon (EC) and fifty-two polycyclic aromatic hydrocarbons (PAHs) in gaseous and particulate phases from seven fuel-stove combinations were studied in a typical rural village in northwest China. For the PAHs, the highest gaseous and particulate phase emission factors (EFs) were both observed for bituminous coal with one-stage stoves, ranging from 459 ± 154 to 1.09 ± 0.36 × 103 mg kg−1. In contrast, the PAHs EFs for the clean briquette coal with two-stage stoves were two orders of magnitude lower than those of the bituminous coals. For parent PAHs (pPAHs) and total quantified PAHs (∑PAHs), they mainly contributed in gaseous phases with compositions of 69–79% and 64–70%, respectively. The gas-to-particle partitioning was mostly governed by the absorption. Moreover, the correlation coefficient (r) between EC and ∑PAHs, OC and parent PAHs (pPAHs), OC and nitro PAHs (nPAHs) were 0.81, 0.67 and 0.85, respectively, supporting that the PAHs species were potential precursors to the EC formation during the solid fuel combustion. The correlation analyses in this study further deduced that the formations of pPAHs and nPAHs were more closely related to that of OC than alkylated PAHs (aPAHs) and oxygenated PAHs (oPAHs). Diagnostic ratios of selective PAHs were calculated and evaluated as well. Among those, the ratio of retene (RET)/[RET + chyrene (CHR)] was found to be an efficient tool to distinguish coal combustion and biomass burning. In general, it was found that the amounts of pollutant emissions from clean briquette coal combustion were definitely lower than those from bituminous coal and biomass combustions. It is thus necessary to introduce and recommend the use of cleaner briquette coal as energy source.

Characteristics and unique sources of polycyclic aromatic hydrocarbons and nitro-polycyclic aromatic hydrocarbons in PM2.5at a highland background site in northwestern China☆.

Polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) in PM2.5 were first observed at a background site (Yuzhong site: YZ site) in the northwestern highlands of China in five seasonal campaigns. Compared with major northwestern cities, PAHs and NPAHs at the YZ site were at a lower level but showed consistent seasonal differences. The PAH and NPAH concentrations peaked in the winter campaigns, which were 36.11±6.54ng/m3 and 418.11±123.55pg/m3, respectively, in winter campaign 1 and 28.97±10.07ng/m3 and 226.89±133.54pg/m3, respectively, in winter campaign 2. These values were approximately a dozen times larger those in other campaigns. The diagnostic ratios indicate that vehicle emissions were the primary source of the PAHs throughout the five campaigns, and coal and biomass combustion also contributed during the winter, summer, and fall campaigns. Among NPAHs, 2-nitrofluoranthene and 2-nitropyrene were generated through OH radical-initiated reactions during atmospheric transport, while 1-nitropyrene came from combustion sources. There is an observation worth pondering, which is that the ratio between pyrene and fluoranthene increased abnormally in the spring and fall campaigns, which is presumably caused by the burning of Tibetan barley straw in the northwestern highlands. The backward trajectories over Tibetan areas in Qinghai and southwestern Gansu are consistent with this hypothesis. In addition, this study reported for the first time that the burning of Tibetan barley straw has become a seasonal contributor to air pollution in northwestern China and is participating in the atmospheric transport of air pollutants driven by the monsoon in East Asia, which urgently requires further research.