Environmental and health risks of VOCs in the longest inner-city tunnel in Xi'an, Northwest China: Implication of impact from new energy vehicles.

Traffic source-dominated volatile organic compound (VOC) samples were collected during four time-intervals in a day (Ⅰ: 7:30-10:30, Ⅱ: 11:00-14:00, Ⅲ: 16:30-19:30, and Ⅳ: 20:00-23:00) in a tunnel in summer, 2019, in Xi'an, China. The total measured VOC (TVOC) in periods Ⅰ and Ⅲ (rush hours, 107.2 ± 8.2 parts per billion by volume [ppbv]) was 1.8 times that in periods Ⅱ and Ⅳ (non-rush hours, 58.6 ± 13.8 ppbv), consistent with the variation in vehicle numbers in the tunnel. The considerably elevated ethane and ethylbenzene levels could have been attributed to emissions from compressed natural gas vehicles and the rapid development of methanol-fueled taxis in Xi'an in 2019. The mixing ratios of benzene, toluene, ethylbenzene, and xylenes (BTEX) contributed 9.4%-12.7% to TVOCs, and the contributions were nearly 40% higher in periods Ⅰ and Ⅲ than in Ⅱ and Ⅳ, indicating that BTEX levels were strongly affected by vehicle emissions. The indicators of motor vehicle emission, namely ethylene, propylene, toluene, m/p-xylenes, o-xylene, and propane, contributed to more than half of the ozone formation potential in this study. The noncarcinogenic risks of VOCs in this study were within the international safety standard, whereas the carcinogenic risks exceeded the standard by 2.3-4.6 times, suggesting that carcinogenic risks were more serious than noncarcinogenic risks. VOCs presented 2.2 and 1.4 times noncarcinogenic and carcinogenic risks during rush hours than during non-rush hours, respectively. Notably, the carcinogenic risk in period Ⅳ was comparable with that in period Ⅲ; however, the vehicle numbers and VOC mixing ratios were the lowest at night, which may have attributed to the increasing number and proportion of methanol M100-fueled vehicles in the tunnel. Therefore, VOCs emitted by new energy vehicles should also be seriously considered while evaluating fossil fuel vehicle emissions.

Effects of domestic solid fuel combustion emissions on the biomarkers of homemakers in rural areas of the Fenwei Plain, China.

BACKGROUND: The health effects of heavy solid fuel use in winter in rural China are of concern. The effects of air pollution resulting from domestic solid fuel combustion in rural households on rural homemakers' biomarkers were revealed in this study. METHODS: In total, 75 female homemakers from rural areas of Guanzhong Basin, the Fenwei Plain, People's Republic of China, were randomly selected and divided into three groups (biomass users, coal users, and nonusers of solid fuel user [control group]). The differences in biological indicators, including 8-hydrox-2'-deoxyguanosine (8-OHdG), interlukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in urine samples as well as blood pressure (BP, including systolic BP [SBP] and diastolic BP [DBP]) and heart rate (HR) among the groups in winter and summer were investigated using statistical analysis. RESULTS: IL-6, 8-OHdG, HR, SBP, and DBP were significantly higher in winter than in summer (P < 0.05) owing to the poor air quality resulted from the excessive use of solid fuels in winter. Significant seasonal differences in 8-OHdG were observed for both coal and biomass users. After the influence of confounders was removed, only IL-6 levels in the urine of solid fuel users were significantly higher than that of the control group. CONCLUSIONS: IL-6 is a sensitive biomarker representing inflammatory responses to particulate matter emitted through household solid fuel combustion. Locally, excessive use of solid fuels in winter posed serious PM2.5 pollution in this area and adverse effects on inflammatory biomarkers in these rural homemakers and induced DNA damage related to oxidative stress.

Characterizations of PM2.5-bound organic compounds and associated potential cancer risks on cooking emissions from dominated types of commercial restaurants in northwestern China.

Cooking emissions are both indoor and outdoor sources for fine particulate matter (PM2.5) but their contributions are often ignored. The PM2.5-bound organic compounds, including alkanols, alkanes, monocarboxylic acids, dicarboxylic acids, and polycyclic aromatic hydrocarbons (PAHs) were determined in the emissions from the most popular types of restaurants in the capital city of northwestern China. The mean concentration of total quantified organic compounds (ΣPM_O) ranged from 1112 to 32,016 ng m-3, with the maximum for the Chinese barbecue restaurants. The ΣPM_O accounted for an average of 11% of PM2.5 mass, demonstrating their significances in the cooking emissions. Hexadecanoic acid (C16) and 1-hexadecanol (C16) were considered as the tracers for stir-frying, steaming, and boiling which are usually applied in the traditional Chinese cuisines; 1-undecanol (C11), 9-fluorenone, and indeno[1,2,3-cd]pyrene were found to be potential markers for grilling and deep-frying which are widely applied in the Western style cooking method. The PAH diagnostic ratios also illustrated their representatives to distinguish the emissions from traditional Chinese cuisines and the Western-style restaurants. The estimated carcinogenic risks for the restaurants that consumed a large amount of oils and employed high temperature cooking methods (e.g., barbecuing and deep-frying) were 2.6-4.2 times exceeded the international safety limit. The organic profiles obtained in this study could be contributed to refine PM2.5 source apportionment in urban areas in northwestern China. The estimations of potential cancer risks urge the establishment of more stringent legislations to protect the health of the catering staffs.

Personal exposure to PM2.5-bound organic species from domestic solid fuel combustion in rural Guanzhong Basin, China: Characteristics and health implication.

Domestic solid fuels combustion produces a mass of fine particulate matter (PM2.5). PM2.5-bound organics, including polycyclic aromatic hydrocarbons (PAHs), oxygenated-PAHs (OPAHs), phthalate esters (PAEs) and hopanes, were quantified in indoor, outdoor and personal exposure samples collected in rural Guanzhong Basin, China. The average concentration of total quantified PAHs in personal exposure samples was 310 ±â€¯443 ng m-3, 1.5 times of those of indoor (211 ±â€¯120 ng m-3) and outdoor (189 ±â€¯115 ng m-3). Similar observations were found for the OPAHs and PAEs, i.e., much higher concentrations were seen in personal exposure samples. Hopanes average personal exposure concentration (13 ±â€¯9.7 ng m-3) was comparable to indoors (15 ±â€¯9.7 ng m-3) and outdoors (13 ±â€¯9.6 ng m-3). Among four common heating ways applied in Chinese dwelling, the highest exposure levels to PAHs, OPAHs and PAEs were found for indoor coal chunks stoves. Concentration under electric power was 1.2-4.5 folds lower than those with solid fuels in this study, proved to be the cleanest energy for the household heating. The exposures to PM2.5 on cell viabilities were also investigated. The largest reduction of 70% on cell viabilities was seen for indoor coal chunks stove housewives, indicating that the emissions from coal combustion had the greatest cytotoxic effects. The results evidenced that the heating ways in rural area could greatly impact on the housewife health in northwestern China. Advanced heating technology and protection should be conducted to reduce the personal exposures to PM2.5 from domestic solid fuel combustions.