Levels, characteristics and health risk assessment of VOCs in different functional zones of Hefei

Risk-oriented source apportionment and implications for mitigation strategies of VOCs in industrial parks: Insights from odor pollution and health risks

A typical industrial park in the upper reaches of the Yangtze River Economic Belt, which is 70 km from the Chongqing urban center, was used to investigate the occurrence and exposure of harmful volatile organic compounds (VOCs). An exposure risk method and a risk-oriented source apportionment approach were performed to assess the inhalation risks and apportion VOC sources, respectively. The quantitative relationships between risk factors and pollution sources were established, identifying key pathogenic and odorous VOCs. The quantitative emission reduction strategies were developed based on risk thresholds. Residents within the industrial parks face potential health risks due to pathogenic VOCs and nuisance odors, and workers in specific sectors experience two to six times higher risks than those in residential areas. Six risk sources were identified in the industrial park, ranked according to their contribution to VOC concentrations as follows: industrial sewage treatment (IST) (32.59 %), natural gas chemical industry (NGCI) (27.77 %), diesel vehicle exhaust (DVE) (12.04 %), pharmaceutical manufacturing industry (PMI) (11.14 %), chemical raw materials manufacturing (CRMM) (9.96 %), and iron and steel industry (ISI) (6.5 %). Among these, NGCI, IST, and CRMM were the top contributors to pathogenic risks, with contributions of 32.13 %, 29.71 %, and 21.71 % to non-carcinogenic risks, and 18.15 %, 19.87 %, and 27.99 % to carcinogenic risks, respectively. DVE produced significantly higher odor pollution compared to other sources, with intensities that were 3 to 10 times greater. The key pathogenic and odorous VOCs differ by source, resulting in varying control priorities for different VOC species. Reducing emissions from these six sources for 20 high-risk species (e.g., acrolein, 2-chlorotoluene, 1,2-dibromoethane, dichloromethane, and p-diethylbenzene) will simultaneously lower pathogenic and odor risks, with cumulative reduction rates ranging from 4.11 % to 93.75 %. This study provides quantitative control targets for VOCs from a health risk perspective, offering valuable guidance for developing risk management policies in industrial parks.

Temporal Variation and Industry-Specific Differences of the Use of Volatile Organic Compounds from 2018 to 2023 and Their Health Risks in a Typical Industrially Concentrated Area in South China

The risk of occupational exposure to organic solvents varies across industries due to factors such as processing materials, ventilation conditions, and exposure duration. Given the dynamic nature of organic solvent use and occupational exposures, continuous monitoring and analysis are essential for identifying high-risk hazards and developing targeted prevention strategies. Therefore, this study aims to analyze the use of organic solvents and volatile organic compounds (VOCs) in different industries in Bao'an District, Shenzhen, China, from 2018 to 2023, to understand their temporal variation and industry-specific differences and to identify high-risk occupational hazards. This study includes 1335 organic solvent samples, used by 414 different industry enterprises, and 1554 air samples. The result shows that the usage of organic solvents in various industries decreased with the outbreak of the pandemic and, conversely, increased as the situation improved. The most frequently detected volatile components in organic solvents were alkanes, followed by aromatic hydrocarbons. The ratios of the detection frequency of VOCs to the total number of detected categories increased year by year after 2020, indicating a tendency towards reduction and concentration of the types of organic solvents used in industrial production. Among the 8 high-risk VOCs, toluene (22.5%), n-hexane (22.0%), xylene (16.1%), and ethylbenzene (15.3%) have relatively high detection rates, suggesting that they need to be focused on in occupational health. Through air samples, the results show that trichloroethylene and xylene pose a high risk to human health (HQ > 1). We recommend that industry should strengthen monitoring of these two VOCs.

Spatiotemporal variations, sources, and atmospheric transformation potential of volatile organic compounds in an industrial zone based on high-resolution measurements in three plants

Industrial emissions are significant sources of volatile organic compounds (VOCs). This study conducted a field campaign at high temporal and spatial resolution to monitor VOCs within three plants in an industrial park in southern China. VOC concentrations showed significant spatial variability in this industrial zone, with median concentrations of 75.22, 40.53, and 29.41 μg/m3 for the total VOCs in the three plants, respectively, with oxygenated VOCs (OVOCs) or aromatics being the major VOCs. Spatial variability within each plant was also significant but VOC-dependent. Seasonal variations in the VOC levels were governed by their industrial emissions, meteorological conditions, and photochemical losses, and they were different for the four groups of VOCs. The temporal and spatial variations in the VOC compositions suggest similar sources of each class of VOCs during different periods of the year in each plant. The diurnal patterns of VOCs (unimodal or bimodal) clearly differed from those at most industrial/urban locations previously, reflecting a dependence on industrial activities. The secondary transformation potential of VOCs also varied temporally and spatially, and aromatics generally made the predominant contributions in this industrial park. The loss rate of OH radicals and ozone formation potential were highly correlated, but the linear relationship substantially changed in summer and autumn due to the intensive emissions of an OVOC species. The lifetime cancer and non-cancer risks via occupational inhalation of the VOCs in the plants were acceptable but merit attention. Taking the secondary transformation potential and health risks into consideration, styrene, xylene, toluene, trichloroethylene, and benzene were proposed to be the priority VOCs regulated in the plants.

VOC source apportionment, reactivity, secondary transformations, and their prioritization using fuzzy-AHP method in a coal-mining city in India

This study assessed the air quality status in different functional zones of Dhanbad-a coal-mining and industrial hub, based on the measurement of aromatic and halogenated volatile organic compounds (VOCs) using gas chromatography. The study encompasses source apportionment of VOCs and their chemical reactivity in terms of OH radical loss rate (LOH), ozone-forming potential (OFP), and their secondary organic aerosol forming potential (SOAp). Furthermore, prioritization of VOCs based on a fuzzy-analytical hierarchical process (F-AHP) has also been done. The results found xylene species to have the highest concentration in all three seasons across traffic-intersection and industrial zones and toluene at the institutional zone. The study identified four sources using positive matrix factorization (PMF) model, viz., mixed traffic exhaust (35%), coal combustion sources (30%), industrial (26%), and solvent usage (9%). LOH and SOAp were ~ 16 times more at the industrial and traffic-intersection zone than the institutional zone. The aromatic species contributed 97% to the OFP, and many species exhibited less contribution to the mixing ratio of VOCs but displayed a high contribution to LOH, OFP, and SOAp, suggesting the need to prefer reactivity-based strategies in addition to concentration-based strategies in the future for their regulation. The F-AHP-based priority component analysis identified 16 species out of 29 in the priority watch list (nine in tier-1, four in tier-2, and three in tier-3). The paucity of data and lack of ambient air quality standards on VOCs (except benzene) make it difficult to determine which aspect should be dealt with first and which species require more attention. Therefore, the F-AHP method used in this study could help identify the influencing parameters to be considered while devising efficient VOC management policies.

Release characteristics of volatile organic compounds at residential garbage collection points: a case study of Hangzhou, China

With the implementation of garbage classification, perishable waste has become increasingly concentrated. This has led to a significant change in the VOC release characteristics at residential garbage collection points, posing a potential risk with unknown characteristics. This study investigated the release characteristics, odor pollution, and health risks of VOCs at garbage collection points under different classification effectiveness, seasons, garbage drop-off periods, and garbage collection point types. The results showed that the average concentration of VOCs released from the garbage sorting collection points (SPs) was 341.43 ± 261.16 μg/m3, and oxygenated compounds (e.g., ethyl acetate and acetone) were the main VOC components. The VOC concentration increased as the community classification effectiveness improved, and it was higher in summer (followed by spring, autumn, and winter). Moreover, the VOC concentrations were higher in the evenings than in the mornings and at centralized garbage collection points (CPs) than at SPs. Further, odor activity value (OAV) assessments indicated that acrolein, styrene, and ethyl acetate were the critical odorous components, with an average OAV of 0.87 ± 0.85, implying marginal odor pollution in some communities. Health risk assessments further revealed that trichloroethylene, benzene, and chlorotoluene were the critical health risk substances, with an average carcinogenic risk (CR) value of 10-6-10-4, and a non-carcinogenic risk (HI) value < 1. These results indicated that HIs were acceptable, but potential CRs existed in the communities. Therefore, VOC pollution prevention and control measures should be urgently strengthened at the garbage collection points in high pollution risk scenarios.

Molecular mechanisms of 1,2-dichloroethane-induced neurotoxicity

The production of industrial solvents and adhesives often utilizes 1,2-dichloroethane (1,2-DCE), a highly toxic halogenated hydrocarbon compound. Occupational 1,2-DCE poisoning occurs frequently and is a public health concern. Exposure to 1,2-DCE can damage the brain, liver, and kidneys. The main and most severe damage caused by exposure to 1,2-DCE is to the nervous system, especially the central nervous system. Current research on 1,2-DCE mainly focuses on the mechanism of brain edema. Several possible mechanisms of 1,2-DCE neurotoxicity have been proposed, including oxidative stress, calcium overload, blood-brain barrier damage, and neurotransmitter changes. This article reviews the research progress on 1,2-DCE neurotoxicity and the mechanism behind it to provide a scientific basis for the prevention and treatment of 1,2-DCE poisoning.

Identify Primary Air Pollution Sources of BTEX by Using Positive Matrix Factorization (PMF): A Case Study of Ho Chi Minh City, Vietnam

Ho Chi Minh City (HCMC) is one of the main socioeconomic and financial centers of Vietnam. The city also faces serious air pollution. However, the city polluted with benzene, toluene, ethylbenzene, and xylene (BTEX) has rarely been studied. We used positive matrix factorization (PMF) to analyze BTEX concentrations measured at two sampling locations to identify the main sources of BTEX in HCMC. The locations represented residential area (i.e., To Hien Thanh) and industrial area (i.e., Tan Binh Industrial Park). At the To Hien Thanh location, the average concentrations of benzene, ethylbenzene, toluene, and xylene were 6.9, 14.4, 4.9, and 12.7 µg/m3, respectively. At the Tan Binh location, the average concentrations of benzene, ethylbenzene, toluene, and xylene were 9.8, 22.6, 2.4, and 9.2 µg/m3, respectively. The results showed that PMF was a reliable model for source apportionment in HCMC. Traffic activities were the main sources of BTEX. Besides, industrial activities also contributed to BTEX emissions, especially the location near the industrial park. The majority of BTEXs at the To Hien Thanh sampling site come from traffic sources accounting for 56.2%. Activities from traffic and photochemical reactions (42.7%) and industrial sources (40.5%) were the main sources affecting BTEX emissions at the sampling site of Tan Binh Industrial Park. This study can be used as a reference for mitigation solutions to reduce the BTEX emission in HCMC.

BTEX in Ambient Air of Zarand, the Industrial City in Southeast of Iran: Concentration, Spatio-temporal Variation and Health Risk Assessment

The existence of several industries in Zarand, a city in Southeastern Iran, caused challenges for the residents about air pollutants and associated health effects. In the present study, the concentration of benzene, toluene, ethylbenzene, and xylene (BTEX), spatio-temporal distribution and related health risks were evaluated. Passive samplers were used to collect 30 samples in the over the hot and cold periods in 2020. The ordinary Kriging method was used to predict the spatio-temporal distribution of BTEXs. Also, the Monte Carlo simulation was used to evaluate the related carcinogenic and non-carcinogenic risks of BTEX for adults. The ranking of mean concentration of overall toluene, xylene, ethylbenzene, and benzene followed as 82.49 ± 26.86, 30.91 ± 14.04, 4.75 ± 3.28, and 0.91 ± 0.18 µg/m3, respectively. The mean value of lifetime carcinogenic risk (LTCR) for residents related to benzene was 7.52 × 10- 6, indicating a negligible carcinogenic risk for them. Furthermore, the ranking of non-carcinogenic risk calculated through hazard quotient (HQ) for investigated BTEX compounds followed as xylene > benzene > toluene > ethylbenzene over the hot period and xylene > toluene > ethylbenzene over the cold period which all points had HQ < 1. Additionally, according to the findings of the sensitivity analysis, the concentration of benzene was the main contributor in increasing the carcinogenic risk. According to our results, it can be stated that the existence of several industries in the study area could not possibly occur the significant carcinogenic and non-carcinogenic risks to the adults residents in the study period. Human studies are recommended to determine definite results.

Emission characteristics and quantitative assessment of the health risks of cooking fumes during outdoor barbecuing

Given the increasing popularity of outdoor barbecue activities and the disregard for barbecue fumes, this study systematically investigated barbecue fume emission characteristics for three types of grilled meats. Particulate matter and volatile organic compounds (VOCs) were continuously measured, and polycyclic aromatic hydrocarbons (PAHs) were isolated from the particulate matter. Cooking emission concentrations depended strongly on the type of meat being cooked. Fine particles were the main particles detected in this study. Low and medium-weight PAHs were the dominant species for all cooking experiments. The mass concentration of total VOCs in the barbecue smoke of the three groups showed significant differences (p < 0.05) and was 1667.18 ± 10.49 μg/m³ in the chicken wing group, 904.03 ± 7.12 μg/m³ in the beef steak group, and 3653.37 ± 12.22 μg/m³ in the streaky pork group. The results of risk assessment showed that the toxicity equivalent quality (TEQ) of carcinogenic PAHs in the particulate matter was significantly higher in the streaky pork group than in the chicken wing and beef steak groups. The carcinogenic risk of benzene exceeds the US EPA standard (1.0E-6) in all types of fumes. Although the hazard index (HI) was below one in all groups for noncarcinogenic risks, it was not cause of optimism. We conjecture that only 500 g of streaky pork would exceed the noncarcinogenic risk limit, and the mass required for carcinogenic risk may be less. When barbecuing, it is essential to avoid high-fat foods and strictly control the fat quantity. This study quantifies the incremental risk of specific foods to consumers and will hopefully provide insight into the hazards of barbecue fumes.

Profile of atmospheric VOC over the Yellow Sea, China: A tale of distribution, constraints, and sources

In the winter of 2018-2019, 75 air samples were collected through four ship-borne measurements in the Yellow Sea (YS) to assess the levels, confinement processes, and source distribution of volatile organic compounds (VOCs). A total of 41 were eventually detected, which mainly were non-methane hydrocarbons (NMHCs), volatile halogenated hydrocarbons (VHCs), oxygenated volatile organic compounds (OVOCs), and volatile organic sulfur compounds (VSCs). Aromatics (31.93 %) and alkenes (11.04 %) in the atmosphere of the YS accounted for a larger proportion of NMHCs compared with the coastal areas. C3-C5 alkanes, propylene, and chloroform exhibited strong latitudinal gradients and opposite latitudinal distributions in the North and South YS, highlighting the strong contribution of regional outflow to YS's atmosphere. The level of Σ41VOCs increased significantly during the heavy pollution period with some chemical monomers detected, which was further enhanced by the emissions from industrial parks near the Liaodong Peninsula and the Shandong Peninsula. Five main VOC sources were identified by the Positive matrix factorization (PMF) model, which were industrial emissions (13.33 %), fuel use and volatilization (6.67 %), Freon R-22 emissions (33.33 %), oil and gas production (20.00 %), and solvent volatilization (26.67 %). These observations revealed the strong causal relationship between coastal air mass transport and the atmosphere in the marginal sea and emphasized that full attention should be paid to the unintentional and unorganized emission of chemical monomers in the industrial process.

Improving VOC control strategies in industrial parks based on emission behavior, environmental effects, and health risks: A case study through atmospheric measurement and emission inventory

Industrial parks have a very important impact on regional economic development, but the extremely complex and relatively concentrated volatile organic compound (VOC) emissions from industrial parks also result in it being difficult to control VOCs. In this study, we took a large integrated industrial park in the upper reaches of the Yangtze River as an example, conducted a 1-year monitoring campaign of ambient air VOCs, and established a speciated VOC emission inventory based on the measured chemical profiles of the key industries. The comprehensive control index (CCI) of 125 VOCs was evaluated using the entropy weighting method based on comprehensive consideration of three aspects, namely, emission behavior, environmental effects, and health risks of VOCs, to identify priority VOC species and their key sources for VOC control in industrial parks. The total estimated VOC emissions in the industrial park in 2019 were 6446.96 t. Steel production, sewage treatment, natural gas chemical industry, pharmaceuticals, and industrial boilers were the main sources of VOC emissions. In terms of VOC components, halocarbons, aromatics, and OVOCs were the largest groups of VOCs emitted from the industrial park, accounting for 73.75 % of the total VOC emissions. Using the entropy weighting method, we evaluated the index weights of five parameters: emissions, ozone formation potential, secondary organic aerosol formation potential, hazard quotient, and lifetime cancer risk. Based on the CCI, five control levels for VOC species were further established. The VOC species in Level I and Level II, which contain species such as naphthalene, 2-chlorotoluene, benzene, acrolein, and chloroform, should be considered as extremely important priority control species. These results serve as a reference for the development of precise control strategies for VOCs in industrial parks.

Exposure to Volatile Organic Compounds in Paint Production Plants: Levels and Potential Human Health Risks

A wide range of volatile organic solvents, including aliphatic and aromatic hydrocarbons, alcohols, and ketones, are used in the production of paints, and they comprise more than 30% of the ingredients of paints. The present study was designed to evaluate the occupational exposure to 15 volatile organic compounds (VOCs, including benzene, toluene, ethylbenzene, xylene, styrene, n-hexane, n-heptane, n-nonane, trichloroethylene, tetrachloroethylene, n-butyl acetate, n-octane, n-decane, dichlorofluoromethane, and acetone) in Iranian paint production factories and subsequently, the associated health risks. The samples were collected from the respiratory zone of workers using the NIOSH 1501 method, and their qualitative and quantitative characterization was performed using gas chromatography-mass spectrometry and gas chromatography-flame ionization detector, respectively. The individual concentrations of VOCs ranged from 23.76 ± 0.57 µg m^-3 (acetone) to 92489.91 ± 0.65 µg m^-3 (m,p-xylene). The predominant compounds were m,p-xylene (up to 92489.91 ± 0.65 µg m^-3), ethylbenzene (up to 91188.95 ± 0.34 µg m^-3), and toluene (up to 46088.84 ± 0.14 µg m^-3). The non-cancer risks of benzene, n-nonane, trichloroethylene, tetrachloroethylene, xylene, and ethylbenzene surpassed the reference value in most of the sectors. In addition, total lifetime risks of cancer were in the range of 1.8 × 10^-5-3.85 × 10^-3, suggesting that there was a risk of carcinogenesis in all studied sections, mainly due to ethylbenzene and benzene. Considering their high exposure concentrations and their associated non-carcinogenic and carcinogenic risks, biological monitoring of workers and the use of technical and modern engineering control measures are recommended.

Occupational health risk assessment of the benzene exposure industries: a comprehensive scoring method through 4 health risk assessment models

Benzene is one of the most common occupational hazards in the working environment which was in the list of group 1 carcinogens. This study applied four occupational health risk assessment models: EPA model; MOM model of Singapore; the International Council on Mining and Metals (ICMM) model, and the Technical guide WS/T 777-2021 of China. The models assessed both non-carcinogenic and carcinogenic effects of benzene for 1629 employees in 50 factories in Jiangsu Province (China) who were exposed to benzene in the working environment and analysis the risk between industries by principal component analysis (PCA) method. The highest occupational health hazard of benzene among the five industries is petroleum processing industry, then followed by chemical products manufacturing industry, special equipment manufacturing industry, wood processing and products industry, and at last the pharmaceutical manufacturing industry. The population of abnormal routine blood parameters in the subjects was mostly in the "wood products industry" group, and the concentration of benzene in "wood products industry" group is the lowest in 5 groups. The industries with low exposure concentration have higher blood abnormality rates; this may be caused by the fact that blood damage is more secretive under low occupational health risk.

Health risk assessment of volatile organic compounds (VOCs) in a refinery in the southwest of Iran using SQRA method

Oil industries, such as oil refineries, are important sources of volatile organic compound production. These compounds have significant health effects on human health. In this study, a health risk assessment is carried out on volatile organic compounds (VOCs) in the recovery oil plant (ROP) unit of a refinery in southwest Iran. It was performed using the SQRA method including respiratory risk for chronic daily intake (CDI) of VOCs and cancer risk and non-cancer risk indices. Five locations in the area of oil effluents and five locations in the refinery area (control samples) were considered for evaluation. The sampling was done according to the standard NIOSH-1501 and SKC pumps. The gas chromatography/flame ionization detector (GC/FID) method was used to extract VOCs. The cancer slope factor (CSF) and respiratory reference dose (RFC) were calculated in addition to the respiratory risk (CDI). The end result shows that a significant difference was observed between the concentrations of volatile organic compounds in the two groups of air (P < 0.05). The SQRA risk assessment showed that the risk levels of benzene for workers in the pit area were very high (4-5). Health hazard levels were also evaluated as high levels for toluene (2-4) and moderate levels for xylene and paraxylene (1-3). The cancer risk assessment of volatile organic compounds recorded the highest level of cancer risk for benzene in the range of petroleum effluents (>1). Also, a non-cancer risk (HQ) assessment revealed that benzene had a significant health risk in the range of oil pits (2-3). Based on the results, petroleum industries, including refineries, should conduct health risk assessment studies of volatile organic compounds. The units that are directly related to the high level of VOCs should be considered sensitive groups, and their employees should be under special management to reduce the level of exposure to these compounds and other hazardous compounds.

Characteristics, influence factors, and health risk assessment of volatile organic compounds through one year of high-resolution measurement at a refinery

From January 2020 to December 2020, high-resolution data of volatile organic compound (VOC) concentrations were monitored by online instruments at a petroleum refinery. The measurement results showed that the external contaminants, meteorological conditions and photochemical reactions had a great influence on the VOC data measured in the petroleum refineries. Some significant differences were observed in the emission composition of different refineries, while propene (34.2%), propane (10.2%), n-butane (5.6%), i-pentane (5.0%) were the dominant species emitted from the refinery in this study. The correlations between compounds with similar atmospheric lifetimes were strong (R² > 0.9), which indicated that the diagnostic ratios of these compounds could be used as indicators to identify the refinery emission source. Chronic health effects of non-carcinogenic risk results showed that acrolein had the highest non-carcinogenic risk and other compound-specific health risks may be of less concern in the refining area. Halogenates and aromatics accounted for 97.4% of the total carcinogenic risk values, while 1,2-dibromoethane, chloromethane, benzene, trichloromethane, 1,2-dichloroethane contributed approximately 80% of the total carcinogenic risk assessment values. This research has recorded valuable data about the VOC emission characteristics from the perspective of the high-resolution monitoring of the petroleum refinery. The results of this work will provide a reference to accurately quantify and identify the emission of petroleum refineries and further throw some light on effective VOC abatement strategies.

Reconciling the bottom-up methodology and ground measurement constraints to improve the city-scale NMVOCs emission inventory: A case study of Nanjing, China

Reliable emission estimate of non-methane volatile organic compounds (NMVOCs) is important for understanding the atmospheric chemistry and formulating control policy of ozone (O₃). In this study, a speciated emission inventory of anthropogenic NMVOCs was developed with the refined "bottom-up" methodology and best available information of individual sources for Nanjing in 2017. The total NMVOCs emissions were calculated at 163.2 Gg. It was broken down into the emissions of over 500 individual species and aromatics took the largest fraction (33.3% of the total emissions). Meanwhile, 105 compounds were measured at 5 sites representing different functional zones of Nanjing for one year. The annual mean concentration of totally 105 species varied from 48.5 ppbv to 63.7 ppbv, and alkanes was the most abundant group with its mass fractions ranging 37.2-40.1% at different sites. Constrained by the emission ratios of individual species versus carbon monoxide (CO) based on ground measurement, the total emissions of 105 species (NMVOCs-105) was estimated at 195.6 Gg, 81.1% larger than the bottom-up estimate of NMVOCs-105 (108.0 Gg). The constrained emissions indicated an overestimation of aromatics and underestimation of OVOCs and halocarbons in the bottom-up emission inventory because of the uncertainties in source profiles. O₃ simulation with Community Multi-scale Air Quality (CMAQ) model was conducted for January, April, July and October in 2017 to evaluate the bottom-up and constrained emission estimates. The mean normal bias (MNB) and mean normal error (MNE) values were generally within the criteria (MNB ≤ ±15% and MNE ≤ 30%) for both inventories. The model performance was improved when the constrained estimates were applied, indicating the benefit of ground observation constraints on NMVOCs emission estimation and O₃ simulation. Based on the O₃ formation potential (OFP), 12 key NMVOCs species mainly from surface coating, on-road vehicles and oil exploitation and refinery were identified as the priority compounds for O₃ reduction.

Human health risk assessment and distribution of VOCs in a chemical site, Weinan, China

The study assessed the volatile organic compound (VOC) pollution characteristics in a chemical site in Weinan, China. The results indicated that chloroform, benzene, trichloroethylene, 1,2-dichloroethane, ethylbenzene, 1,2-dichloropropane, and 1,2,3-Trichloropropane exceeded the soil standard limit for soil contamination of development land (GB36600, PRC). Using pollution index, ambient severity, and correlation coefficient revealed industrial production and relocation activities as sources of VOCs contamination in the site. The carcinogenic risk assessed by human exposure to site VOCs through ingestion, respiration, exposure, etc., exceeded the potentially acceptable level (1.0 × 10−6). 1,2,3-trichloropropane has the highest carcinogenic risk across all pathways, regions, and populations. The long-term exposure and emission of VOCs in the investigated sites could likely pose an adverse health risk to site staff and the surrounding sensitive groups. Therefore, it is necessary to carry out strict investigation and evaluation of the site, and timely repair and control to protect the water, soil, and air environment and to avoid the long-term cumulative exposure risk to human health caused by VOCs emission.

Characteristics and health risks of benzene series and halocarbons near a typical chemical industrial park

Health risks of typical benzene series and halocarbons (BSHs) in a densely populated area near a large-scale chemical industrial park were investigated. Ambient and indoor air and tap water samples were collected in summer and winter; and the concentration characteristics, sources, and exposure risks of typical BSH species, including five benzene series (benzene, toluene, ethylbenzene, o-xylene, m,p-xylene) and five halocarbons (dichloromethane, trichloromethane, trichloroethylene, tetrachloromethane, and tetrachloroethylene), were analysed. The total mean concentrations of BSHs were 53.32 μg m^-3, 36.29 μg m^-3, and 26.88 μg L^-1 in indoor air, ambient air, and tap water, respectively. Halocarbons dominated the total BSHs with concentrations relatively higher than those in many other industrial areas. Industrial solvent use, industrial processes, and vehicle exhaust emissions were the principal sources of BSHs in ambient air. The use of household products (e.g., detergents and pesticides) was the principal source of indoor BSHs. Inhalation is the primary human exposure route. Ingestion of drinking water was also an important exposure route but had less impact than inhalation. Lifetime non-cancer risks of individual and cumulative BSHs were below the threshold (HQ = 1), indicating no significant lifetime non-cancer risks in the study area. However, tetrachloromethane, benzene, trichloromethane, ethylbenzene, and trichloroethylene showed potential lifetime cancer risk. The cumulative lifetime cancer risks exceeded the tolerable benchmark (1 × 10^-4), indicating a lifetime cancer risk of BSHs to residents near the chemical industry park. This study provides valuable information for the management of public health in chemical industrial parks.

Urinary metabolites of multiple volatile organic compounds among general population in Wuhan, central China: Inter-day reproducibility, seasonal difference, and their associations with oxidative stress biomarkers

General population are concurrently and extensively exposed to many volatile organic compounds (VOCs), including some Group 1 human carcinogens, such as 1,3-butadiene. However, only a few studies assessed internal exposure levels of VOCs; particularly, very limited studies have examined associations between the urinary concentrations of multiple VOC metabolites (mVOCs) and oxidative stress biomarkers (OSBs) among the general population. In this study, 21 mVOCs and three OSBs including 8-hydroxy-2'-deoxyguanosine (8-OHdG; for DNA), 8-hydroxyguanosine (8-OHG; for RNA), and 4-hydroxy nonenal mercapturic acid (HNEMA; for lipid) were measured in 406 urine samples collected from 128 healthy adults during autumn and winter of 2018 in Wuhan, central China, including repeated samples taken in 3 d from 75 volunteers. Inter-day reproducibility for most mVOCs was good to excellent; urinary concentrations of mVOCs in winter were generally higher than those in autumn. Risk assessment was conducted by calculating hazard quotients for the parent compounds, and the results suggested that acrolein, 1,3-butadiene, and cyanide should be considered as high-priority hazardous ones for management. After false-discovery adjustment, 16 of the studied mVOCs were positively associated with 8-OHdG and 8-OHG (β values ranged from 0.04 to 0.48), and four mVOCs were positively associated with HNEMA (β values ranged from 0.21 to 0.78). Weighted quantile sum regression analyses were used to assess associations of mVOC mixture and OSBs, and we found significantly positive associations between the mixture index and OSBs, among which the strongest mVOC contributors for the associations were 2-methylhippuric acid for both DNA (20%) and RNA (17%) oxidative damage, and trans,trans-muconic acid (50%) for lipid peroxidation. This study firstly reported good to excellent short-term reproducibility, seasonal difference in autumn and winter, and possible health risk in urinary concentrations of multiple mVOCs among the general population.

Characteristics, sources and health risks assessment of VOCs in Zhengzhou, China during haze pollution season

Zhengzhou is one of the most haze-polluted cities in Central China with high organic carbon emission, which accounts for 15%-20% of particulate matter (PM_2.5) in winter and causes significantly adverse health effects. Volatile organic compounds (VOCs) are the precursors of secondary PM_2.5 and O₃ formation. An investigation of characteristics, sources and health risks assessment of VOCs was carried out at the urban area of Zhengzhou from 1^st to 31^st December, 2019. The mean concentrations of total detected VOCs were 48.8 ± 23.0 ppbv. Alkanes (22.0 ± 10.4 ppbv), halocarbons (8.1 ± 3.9 ppbv) and aromatics (6.5 ± 3.9 ppbv) were the predominant VOC species, followed by alkenes (5.1 ± 3.3 ppbv), oxygenated VOCs (3.6 ± 1.8 ppbv), alkyne (3.5 ± 1.9, ppbv) and sulfide (0.5 ± 0.9 ppbv). The Positive Matrix Factorization model was used to identify and apportion VOCs sources. Five major sources of VOCs were identified as vehicular exhaust, industrial processes, combustion, fuel evaporation, and solvent use. The carcinogenic and non-carcinogenic risk values of species were calculated. The carcinogenic and non-carcinogenic risks of almost all air toxics increased during haze days. The total non-carcinogenic risks exceeded the acceptable ranges. Most VOC species posed no non-carcinogenic risk during three haze events. The carcinogenic risks of chloroform, 1,2-dichloroethane, 1,2-dibromoethane, benzyl chloride, hexachloro-1,3-butadiene, benzene and naphthalene were above the acceptable level (1.0  ×  10^-6) but below the tolerable risk level (1.0  ×  10^-4). Industrial emission was the major contributor to non-carcinogenic, and solvent use was the major contributor to carcinogenic risks.

Quantitative and Semiquantitative Health Risk Assessment of Occupational Exposure to Styrene in a Petrochemical Industry

Background

Styrene is one of the aromatic compounds used in acetonitrile-butadiene-styrene (ABS) producing petrochemicals, which has an impact on health of workers. Therefore, this study aimed to investigate the health risks of styrene emitted from the petrochemical industry in Iran.

Methods

Air samples were collected based on NIOSH 1501 method. The samples were analyzed by the Varian-cp3800 gas chromatograph. Finally, risk levels of styrene's health effects on employees were assessed by the quantitative method of the U.S. Environmental Protection Agency (U.S. EPA) and the semiquantitative way by the Singapore Occupational Safety and Health Association.

Results

Based on the results, the employees had the highest average exposure to styrene vapors (4.06 × 10 - 1 m g . ( k g - d a y ) - 1 ) in the polybutadiene latex (PBL) unit. Therefore, the most top predictors of cancer and non-cancer risk were 2.3 × 10 - 4 and 7.26 × 10 - 1 , respectively. Given that the lowest average exposure (1.5 × 10 - 2 m g . ( k g - d a y ) - 1 ) was in the dryer unit, the prediction showed a moderate risk of cancer (0.8 × 10 - 6 ) and non-cancer (2.3 × 10 - 3 ) for the employees. The EPA method also predicted that there would be a definite cancer risk in 16% and a probable risk in 76% of exposures. However, according to the semiquantitative approach, the rate of risk was at the "low" level for all staff. The results showed that there was a significant difference (p < 0.05) between the units in exposure and health risk of styrene (p < 0.05).

Conclusion

Given the high risk of styrene's health effects, appropriate control measures are required to reduce the exposure level.

A wavelet-based random forest approach for indoor BTEX spatiotemporal modeling and health risk assessment

This study reports on BTEX concentrations in one of the largest parking garages in Iran with a peak traffic flow reaching up to ~9300 vehicles in the last few days of the Nowruz holidays. Samples were obtained on different days of the week at three main locations in the Zaer Parking Garage. A novel wavelet-based random forest model (WRF) was trained to estimate BTEX concentrations by decomposing temperature, day of the week, sampling location, and relative humidity data with a maximal overlap discrete wavelet transform (MODWT) function and subsequently inputted into the WRF model. The results suggested that the WRF model can reasonably estimate BTEX trends and variations based on high R2 values of 0.96, 0.95, and 0.98 for training, validation, and test data subsets, respectively. The carcinogenic (LTCR) and non-carcinogenic health risk (HI) assessment results indicated a definite carcinogenic risk of benzene (LTCR = 2.22 × 10-4) and high non-carcinogenic risk (HI = 4.51) of BTEX emissions. The results of this study point to the importance of BTEX accumulation in poorly ventilated areas and the utility of machine learning in forecasting air pollution in diverse airsheds such as parking garages.

Environmental status of an Italian site highly polluted by illegal dumping of industrial wastes: The situation 15 years after the judicial intervention

In 2008 the Italian government classified the Bussi sul Tirino area (Central Italy) as Site of National Interest destined to remediation which, unfortunately, has not yet begun. The decision followed >20 years of illegal dumping of industrial wastes, lasting from 1984 to 2005, that generated the biggest illegal toxic waste disposal site in Europe. The contamination profile of the site was mainly characterized by PCDD/Fs, PCBs, PAHs, chlorinated solvents, Hg, and Pb. Due to the health concern of the population and local authorities, an extensive monitoring and biomonitoring campaign was carried out in 2017-2018, checking the site-specific pollutants in local food (free-range hens' eggs, milk from grazing sheep and goats, wild edible mushrooms, and drinking water), environmental (air and freshwaters) and biological (human urine) matrices. A total of 314 samples were processed, obtaining 3217 analytical data that were compared with regulatory limits, when available, and values reported by international literature. The sum PCDD/Fs and DL-PCBs ranged from 0.24 to 3.6 pg TEQ g^-1 fat, and from 0.46 to 8.3 pg TEQ g^-1 fat, respectively in milk in eggs, in line with the maximum levels established by CE Regulations except for an egg sample. As regards PAHs, all our results were lower than the literature data, as well as for Hg and Pb. Outdoor air showed levels of chlorinated solvents ranging from <LOD to 36 μg m^-3, and freshwaters from 0.21 to 2.8 μg L^-1. All drinking water samples resulted compliant with the maximum levels established by the current EU directive. Despite the severe pollution of the illegal dumping site and the remediation not yet carried out, the local environment and the population living in Bussi and surroundings seem not to be affected by significant exposure to the toxics characterizing the landfill.

Protective effects of resveratrol against the cardiac developmental toxicity of trichloroethylene in zebrafish embryos

Trichloroethylene (TCE), a prevalent environmental contaminant, has been shown to induce cardiac malformations. Resveratrol (RSV) is a natural polyphenolic compound exhibiting protective effects on heart development. To investigate if RSV could protect against TCE-induced heart defects, we exposed zebrafish embryos to TCE (10 ppb) in the presence or absence of RSV (1 μg/mL). Our results showed that RSV significantly attenuated TCE-induced heart defects in zebrafish embryos. The TCE-induced ROS (reactive oxygen species) generation, 8-OHdG (8-hydroxy-2`-deoxyguanosine) formation and cell proliferation were significantly counteracted by RSV. Moreover, RSV attenuated the TCE-induced changes in mRNA expression or activity of genes involved in AHR and Nrf2 signal pathways. We further showed that RSV might inhibit TCE-enhanced cell proliferation by rescuing the downregulation of the p53/p21 axis. In conclusion, our data demonstrates that RSV protects against the cardiac developmental toxicity of TCE by inhibiting AHR activity, oxidative stress and cell proliferation.

High energy efficient degradation of toluene using a novel double dielectric barrier discharge reactor

A double dielectric barrier discharge (DDBD) reactor was established to decompose toluene with high energy efficiency. Differences in discharge characteristics including visual images, voltage-current waveforms, Lissajous figures, and temperature variation, were determined between the DDBD and SDBD reactors. Removal efficiency, mineralization rate, CO₂ selectivity, and energy yield were used to evaluate the toluene abatement performance of the two reactors. Compared to the SDBD reactor, the DDBD reactor exhibited more uniform and stable discharges due to a change in discharge mode. In addition, the DDBD reactor's dissipated power and reactor temperature (including the gas, barrier and ground electrode) were significantly lower than those in the SDBD reactor. At 22-24 kV, the DDBD reactor showed a higher toluene removal efficiency and mineralization rate, while at 14-16 kV, the SDBD reactor exhibited higher respective value. The energy efficiency of the DDBD was 2.5-3 times that of the SDBD reactor, and the overall energy constant k_overall of the DDBD reactor (1.47 mL/J) was significantly higher than that of the SDBD reactor (0.367 mL/J) as revealed by the kinetics study. Lastly, a plausible toluene degradation mechanism in the DDBD and SDBD reactors was proposed based on organic intermediates that formed during toluene decomposition.

Multi-scale volatile organic compound (VOC) source apportionment in Tianjin, China, using a receptor model coupled with 1-hr resolution data

The multi-scale chemical characteristics and source apportionment of volatile organic compounds (VOCs) were analysed in Tianjin, China, using 1-hr resolution VOC-species data between November 1, 2018 and March 15, 2019. The average total VOC (TVOC) concentration was 30.6 ppbv during the heating season. The alkanes accounted for highest proportion of the TVOC, while the alkenes were the predominant species forming ozone, especially ethylene. Compared to the clean period, the concentration of acetylene during the haze events showed highest increase rate, followed by the ethane; and the concentrations and proportions of alkanes and alkenes were highest during the growth stage (GS) of haze events. The multi-scale apportionment results suggested petrochemical industry and solvent usage (PI/SU, 31.2%), vehicle emissions and liquefied petroleum gas (VE/LPG, 20.5%), and combustion emissions (CE, 19.1%) were the main VOC sources during the heating season. Compared to the clean period, the contributions of PI/SU, VE/LPG, CE, and refinery emissions notably increased during the haze events, while that of gasoline evaporation decreased. The contributions of PI/SU and RPI showed significantly increase during the GS of haze events, whereas most sources decreased during the dissipation stage of haze events. Diurnal-variations in source contributions during the haze events were clearer than the clean period, and the contributions of PI/SU, VE/LPG, and CE during the haze events were markedly higher at night. These findings provide valuable information to inform effective VOC control and prevention measures with specific relevance for the control of ozone pollution in Tianjin.

Analysis of roadside air pollutant concentrations and potential health risk of exposure in Hanoi, Vietnam

The large number of vehicles plying in roads is the main cause of traffic jam and air pollution in Hanoi. In this study, the vehicle density and shares of different vehicle types, the traffic flow velocity and roadside air pollutants concentrations were monitored in Chua Boc street, a typical arterial road in the city. The shares of the motorcycle, car and bus fleets in the total on-road traffic in the street were 78.4-87.3, 12.3-20.2 and 0.4-1.4%, respectively. The high density of vehicles caused traffic jam during rush hours and considerably reduced the vehicle speed. The traffic flow velocity during non-rush and rush hours was found to vary from 26.4-34.5 and 10.3-12.1 km/h, respectively. The average concentrations of PM₁₀, PM_2.5, SO₂, NO₂, CO and NMVOC during the rush hours were the following: 117.1 ± 8.5, 65.2 ± 10.6, 113.5 ± 10.9, 138.5 ± 16.0, 6792 ± 998 and 451 ± 71 µg/m³, respectively, which were about 1.9-2.6 times above the levels during non-rush hours. The decrease in vehicle speed during rush hours were strongly correlated with the increase in concentration of PM₁₀ (R² = 0.732), PM_2.5 (R² = 0.685), SO₂ (R² = 0.578), NO₂ (R² = 0.738), CO (R² = 0.689) and NMVOC (R² = 0.747). High levels of these toxic air pollutants in Hanoi city posed a high health risk to humans. Facemask use was more popular among the motorcycle commuters and pedestrians, especially during rush hours, than among the people working for extended time period alongside of the street.

Understanding the sources and spatiotemporal characteristics of VOCs in the Chengdu Plain, China, through measurement and emission inventory

In order to evaluate the volatile organic compounds (VOCs) pollution characteristics in Chengdu and to identify their sources, ambient air sample collection and measurement were conducted at 28 sampling sites covering all districts/counties of Chengdu from May 2016 to January 2017. Meanwhile, a county-level anthropogenic speciated VOCs emission inventory was established by "bottom-up" method for 2016. Then, a comparison was made between the VOCs emissions, spatial variations, and source structures derived from the measurement and emission inventory. Ambient measurements showed that the annual average mixing ratios of VOCs in Chengdu were 57.54 ppbv (12.36 to 456.04 ppbv), of which mainly dominated by alkanes (38.8%) and OVOCs (22.0%). The ambient VOCs in Chengdu have distinct spatiotemporal characteristics, with a high concentration in January at the middle-northern part of the city and a low concentration in September at the southwestern part. The spatial distribution of VOCs estimated by the emission inventory was in good agreement with ambient measurements. Comparison of individual VOCs emissions indicated that the emissions of non-methane hydrocarbon species agreed within ±100% between the two methods. Both positive matrix factorization (PMF) model results and emission inventory showed that vehicle emissions were the major contributor of anthropogenic VOCs in Chengdu (31% and 37%), followed by solvent utilization (26% and 27%) and industrial processes (23% and 30%). The large discrepancies were found between the relative contribution of combustion sources, and the PMF resolved more contributions (20%) than the emission inventory (6%). Overall, this study demonstrates that measurement results and emission inventory were in a good agreement. However, to improve the reliability of the emission inventory, we suggest significant revision on source profiles of oxygenated volatile organic compounds (OVOCs) and halocarbons, as well as more detailed investigation should be made in terms of energy consumption in household.

Emission of volatile organic compounds from a small-scale municipal solid waste transfer station: Ozone-formation potential and health risk assessment

Volatile organic compounds (VOCs) are the main precursors of tropospheric ozone and secondary aerosol generation, posing a threat to human health and affecting the environmental climate. A large quantity of VOCs can be produced in the initial decomposition stage of municipal solid waste (MSW). In this study, the atmosphere in an MSW transfer station was monitored for one year. The emission characteristics of VOCs in different seasons and working hours were analyzed, and the ozone-formation potential of VOCs was calculated through the maximum incremental reaction method, and health risks posed by the VOCs in the MSW transfer station were assessed. The results showed that the highest concentration of VOCs appeared in spring and summer, accounting for 70.6% and 26.6% of total VOCs (TVOCs) in peak working periods, respectively. Oxygenated compounds and terpenes contributed most to ozone formation, accounting for 41.0% and 50.6% of total ozone formation, respectively. The carcinogenic risks were above the safe threshold, labeled "probable risks". Tetrachloroethylene and 1,2-dichloroethane were the main contributors to carcinogenic risks. The mean non-carcinogenic risks were within the safe threshold in the MSW transfer station. From the perspective of protecting human health and ecological environmental safety, VOC control needs to be further strengthened in the transfer station.

Compositions, sources and health risks of ambient volatile organic compounds (VOCs) at a petrochemical industrial park along the Yangtze River

Petrochemical industry (PI) is an important emission sector of anthropogenic volatile organic compounds (VOCs). The health impacts of VOCs from PI have caused a wide attention by both scientists and publics. In this study, compositions, sources and health risks of VOCs at a typical petrochemical industrial park along the middle reach of Yangtze River were studied. The total VOC concentrations were in the range of 5.59 to 541 ppbv with a mean value of 54.8 ppbv. Alkanes (41.4 ± 15.7%) were the predominant group, followed by alkenes (19.9 ± 18.3%), OVOCs (14.7 ± 9.26%), halo hydrocarbon (11.2 ± 6.42%), aromatics (8.17 ± 5.08%), and acetylene (4.54 ± 2.80%). Compound-specific health risk results showed that acrolein and 1,3-butadiene had the highest non-carcinogenic risk (expressed by hazard ratio, HR: 22.8) and carcinogenic risk (expressed by lifetime cancer risk, LCR: 6.7 × 10^-3), respectively. Positive matrix factorization (PMF) model identified four VOC sources including fuel evaporation, industrial sources, ethylene industry and regional background with the average contributions of 35.6%, 12.0%, 26.5% and 25.9%, respectively. The receptor-originated approach combining the PMF model and conventional methods (HR and LCR) was used to assess the source-specific health risks. The non-cancer risks of four VOC sources were above safe level with regional background contributing most (38.3% or 4.91) to HR. The cancer risks of the four sources were below the tolerable level (<10^-4) and regional background also contributed most, with relative contribution of 58.4% (or 10^-4.22) to LCR. Our results are conductive to the formulation of countermeasures to reduce human exposure to ambient VOCs at petrochemical industrial parks in China.

Emission characteristics and health risk assessment of VOCs from a food waste anaerobic digestion plant: A case study of Suzhou, China

The process of anaerobic digestion in food waste treatment plants generates a large amount of volatile organic compounds (VOCs). Long-term exposure to this exhaust gas can pose a threat to the health of workers and people living nearby. In this study, VOCs emitted from different working units in a food waste anaerobic digestion plant were monitored for a year. Variations in VOCs emitted from each unit were analyzed and a health risk assessment was conducted for each working unit. The results show that the concentration of VOCs in different units varied greatly. The highest cumulative concentration of VOCs appeared in the hydrothermal hydrolysis unit (3.49 × 10⁴ μg/m³), followed by the sorting/crushing room (8.97 × 10³ μg/m³), anaerobic digestion unit (6.21 × 10² μg/m³), and biogas production unit (2.01 × 10² μg/m³). Oxygenated compounds and terpenes were the major components of the emitted VOCs, accounting for more than 98% of total VOC emissions. The carcinogenic risk in the plant exceeded the safety threshold (ILCR<1 × 10^-6), while the non-carcinogenic risk was within the acceptable range (HI < 1). The carcinogenic risk from the hydrothermal hydrolysis unit was the highest, reaching 4.4 × 10^-5, and was labeled as "probable risk." The carcinogenic risk at the plant boundary was 1.2 × 10^-5, indicating exhaust gases can cause a health threat to neighbors. Therefore, management VOCs in anaerobic digestion plants should receive more attention, and employees should minimize the time they spend in the hydrothermal hydrolysis unit.

In situ assembly of CQDs/Bi2WO6 for highly efficient photocatalytic degradation of VOCs under visible light

A facile strategy of the assembly of CQD/Bi₂WO₆ hybrid materials, which exhibit highly efficient photocatalytic degradation of pollutants under visible light.

Enhancing biofilm formation in biofilters for benzene, toluene, ethylbenzene, and xylene removal by modifying the packing material surface

Polyurethane (PU) sponges are popular packing material in biofilters and their smooth and hydrophobic surface often leads to an uneven distribution and detachment of biofilms. In this work, the surface of PU sponge was modified to obtain higher roughness and positive charge. The performances of two biofilters (BF1 with pristine sponge and BF2 with modified sponge) for benzene, toluene, ethylbenzene, and xylene (BTEX) removal were investigated. Total Volatile Organic Compound (TVOC) removal efficiency and CO₂ increment were 61% and 804 ppm for BF2 respectively after start-up, compared with 51% and 538 ppm for BF1. Analysis on biofilms showed that the modification of PU sponge significantly improved the microbial growth, viability and adhesive strength in biofilms, reduced extracellular polymeric substance (EPS) and changed the microbial community. These results demonstrate that modified sponge can enhance biofilm formation and BTEX removal in biofilters and may applied in large-scale applications.

BTEX compositions and its potential health impacts in Malaysia

This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) and assess the risk to health at different sites in Malaysia. Continuous monitoring of BTEX in Kuala Lumpur City Centre, Kuala Terengganu, Kota Kinabalu and Fraser Hill were conducted using Online Gas Chromatograph. For comparison, BTEX at selected hotspot locations were determined by active sampling method using sorbent tubes and Thermal Desorption Gas Chromatography Mass Spectrometry. The hazard quotient (HQ) for non-carcinogenic and the life-time cancer risk (LTCR) of BTEX were calculated using the United States Environmental Protection Agency (USEPA) health risk assessment (HRA) methods. The results showed that the highest total BTEX concentrations using continuous monitoring were recorded in the Kuala Lumpur City Centre (49.56 ± 23.71 μg/m³). Toluene was the most dominant among the BTEX compounds. The average concentrations of benzene ranged from 0.69 ± 0.45 μg/m³ to 6.20 ± 3.51 μg/m³. Measurements using active sampling showed that BTEX concentrations dominated at the roadside (193.11 ± 114.57 μg/m³) in comparison to petrol station (73.08 ± 30.41 μg/m³), petrochemical industry (32.10 ± 13.13 μg/m³) and airport (25.30 ± 6.17 μg/m³). Strong correlations among BTEX compounds (p<0.01, r>0.7) at Kuala Lumpur City Centre showed that BTEX compounds originated from similar sources. The values of HQ at all stations were <1 indicating the non-carcinogenic risk are negligible and do not pose threats to human health. The LTCR value based on benzene inhalation (1.59 × 10^-5) at Kuala Lumpur City Centre were between 1 × 10^-4 and 1 × 10^-5, representing a probable carcinogenic risk.

Temporal variations of atmospheric benzene and its health effects in Tehran megacity (2010-2013)

The main aims of the present research were (1) investigation of the temporal trends of atmospheric benzene concentrations in Tehran city during the period 2010 to 2013 and (2) assessment of carcinogenic and non-carcinogenic health risks of inhalation exposure to benzene. For the first objective, the data of ambient air benzene concentrations were derived from 15 air quality monitoring stations (AQMSs) in Tehran during the years 2010 to 2013 and they were temporally investigated after data cleaning and missing data imputation. The excess lifetime cancer risk (ELCR) and hazard quotient (HQ) were estimated to reveal the carcinogenic and non-carcinogenic health effects of exposure to ambient benzene. Our findings indicated that over 2010-2013, annual mean concentrations of benzene were in the range of 1.84 to 2.57 μg m^-3, and the highest annual mean concentration was observed in 2011 with a mean of 2.57 μg m^-3. The four-year average concentration of benzene during the period from 2010 to 2013 was 2.14 μg m^-3. Furthermore, the HQ for inhalation exposure to ambient benzene was lower than the acceptable risk level (HQ < 1) over the study time period which indicated that the non-carcinogenic effects are very unlikely to happen. In addition, health risk assessment for ELCR showed that the potential cancer risk for inhalation exposure to benzene was 1.67 × 10^-5 over the study period, which is significantly higher than the limits recommended by the U.S. EPA (1 × 10^-6). Our study clearly proves that the ambient benzene concentration in Tehran has substantially higher carcinogenic effects on the population. Appropriate sustainable control measures should be taken to reduce air benzene concentration and protect public health.

Similarities and differences in PM10 and PM2.5 concentrations, chemical compositions and sources in Hefei City, China

Atmospheric particulates were sampled in Hefei City, China from October 2016 to January 2017 to compare chemical compositions and sources of PM_2.5 (particle size smaller than 2.5 μm) and PM₁₀ (particle size smaller than 10 μm). The mean levels of PM_2.5 and PM₁₀ were 81 and 109 μg/m³, which are higher than the health threshold levels regulated by national and international standards. During the sampling period, AQI (Air Quality Index) was strongly correlated with PM_2.5 (Pearson's coefficient r = 0.94) rather than PM₁₀ concentrations. The PM_2.5/PM₁₀ ratios were approximately 0.7, revealing the characteristics of fine particle pollution. Pollution elements (S, Zn, Cu and Pb) took up a large proportion of the composition and had high enrichment factors of 437, 385, 20 and 53, respectively, in PM₁₀. Coal combustion and high-tech manufacture industry discharges were suggested to be the main pollution sources of both PM_2.5 and PM₁₀. The PM_2.5/PM₁₀ ratios of anthropogenic element concentrations were much higher than ratios of earth crust element. As compared to PM₁₀, S and Pb in PM_2.5 had larger EFs, indicating that pollution elements were predominantly enriched in PM_2.5. Furthermore, a paired sample t-test confirmed similar sources of PM_2.5 and PM₁₀. Our study provides basic database to evaluate the heavy metal pollution status of atmospheric particulates in Chinese cities.