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The chemical and cytotoxicity properties of fine particulate matter (PM2.5) at indoor and outdoor environment were characterized in Xi'an, China. The mass concentrations of PM2.5 in urban areas (93.29~96.13 μg m−3 for indoor and 124.37~154.52 μg m−3 for outdoor) were higher than suburban (68.40 μg m−3 for indoor and 96.18 μg m−3 for outdoor). The PM2.5 concentrations from outdoor environment due to fossil fuel combustion were higher than indoor environment. An indoor environment without central heating demonstrated higher organic carbon-to-elemental carbon (OC / EC) ratios and n-alkanes values that potentially attributed to residential coal combustion activities. The cell viability of human epithelial lung cells showed dose-dependent decrease, while nitric oxide (NO) and oxidative potential showed dose-dependent increase under exposure to PM2.5. The variations of bioreactivities could be possibly related to different chemical components from different sources. Moderate (0.4 < R < 0.6) to strong (R > 0.6) correlations were observed between bioreactivities and elemental carbon (EC)/secondary aerosols (NO3−, SO42−, and NH4+)/heavy metals (Ni, Cu, and Pb). The findings suggest PM2.5 is associated with particle induced oxidative potential, which are further responsible for respiratory diseases under chronic exposure. [ABSTRACT FROM AUTHOR]

To insight the urban volatile organic compound (VOC) profiles and its contribution to ozone, four-time per day (8:00–9:00, 15:00–16:00, 19:00–20:00, and 23:00–24:00) off-line VOC samples were collected from 16th July to 28th July 2018 for a summer investigation campaign over Xi'an, China. The diurnal variation was significant that the lowest TVOC concentrations were observed in the midnight period (28.4 ± 25.6 ppbv) while the highest was shown in the morning (49.6 ± 40.1 ppbv). The differences of total non-methane VOCs (TVOCs) between weekdays and weekend were also significant that the weekend showed significantly high VOC levels than weekdays (p < 0.05) but did not lead to significant ambient O3 increase (p > 0.05). Isopentane, a general marker for vehicle exhaust, showed descending concentrations from morning to midnight and good correlation with vehicle numbers on road, indicating a potential source to the VOCs at this site. The results from PMF proved that vehicular exhaust was the largest source to the VOCs in this study (64.4%). VOC categories showed a reverse sequence in abundance of concentrations and OFP contributions that alkenes showed the highest OFPs although with the lowest abundance in TOVCs due to their high reactivity in photochemical reactions. High OFPs from ethylene and isopentane indicated that vehicular emissions could be the largest potential OFP source in this site. OFPs from isoprene (from 1.85 to 13.4 ppbv) indicated that biogenic VOCs should not be negligible in urban Xi'an city when controlling O3 pollutants. Comparison of two OFP methods was conducted and MIR method was proved to be more reasonable and scientific in summer Xi'an. Therefore, vehicular emission, the largest contributor to ambient VOCs and also OFPs, as well as biological source should be priority controlled in guiding VOC emissions and reducing O3 control policies. [ABSTRACT FROM AUTHOR]

Three urban environments, office, apartment and restaurant, were selected to investigate the indoor and outdoor air quality as an inter-comparison in which CO, particulate matter (PM) concentration and particle size ranging were concerned. In this investigation, CO level in the apartment (623 ppm) was the highest among the indoor environments and indoor levels were always higher than outdoor levels. The PM (333 µg/m), PM (213 µg/m), PM (148 µg/m) concentrations in the office were 10-50 % higher than in the restaurant and apartment, and the three indoor PM levels all exceeded the China standard of 150 µg/m. Particles ranging from 0.3 to 0.4 µm, 0.4 to 0.5 µm and 0.5 to 0.65 µm make largest contribution to particle mass in indoor air, and fine particles number concentrations were much higher than outdoor levels. Outdoor air pollution is mainly affected by heavy traffic, while indoor air pollution has various sources. Particularly, office environment was mainly affected by outdoor sources like soil dust and traffic emission; apartment particles were mainly caused by human activities; restaurant indoor air quality was affected by multiple sources among which cooking-generated fine particles and the human steam are main factors. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) attached to particulate matter can affect respiratory health, especially the health of children, but information on the air quality in schools is generally lacking. This study investigated the PAH concentrations in a naturally ventilated classroom in Xi'an, China, from 16 to 31 May 2012. Particulate PAH concentrations were measured for samples collected on five-stage cascade impactors deployed inside the classroom and outside. PM-bound PAH concentrations were 53.2 ng m indoors and 72.9 ng m outdoors. PAHs attached to very fine particles (VFPs) accounted for ~70 % of the total PAHs. The PAH concentrations indoors were affected by the students' activities, cleaning, and smoking, while outdoors, the main sources were motor vehicle emissions and contaminated road dust. Particle-bound PAHs infiltrated the classroom through open windows, but the activities of the students and staff were also associated with an increase of PAHs attached to particles larger than 1.0 µm, most likely through resuspension. Cycles in the sources led to PAH concentrations 2-3 times higher on weekdays compared to weekends, both indoors and outdoors. PAH toxicity risks inside the classroom were substantially lower than those outdoors, and the highest risks were associated with VFPs. [ABSTRACT FROM AUTHOR]

The chemical and bioreactivity properties of fine particulate matter (PM 2.5) in indoor and outdoor environments in Xi'an were characterized, and the lung function of various participants was investigated. The concentrations of polycyclic aromatic hydrocarbons (PAHs), oxygenated polycyclic aromatic hydrocarbons, and nitrated polycyclic aromatic hydrocarbons were higher in outdoor environments than in indoor environments; in addition, urban areas had higher concentrations of these compounds than did suburban areas, with fossil fuel combustion likely being the primary source. Moreover, PM 2.5 -induced inflammation was higher in urban areas than in suburban areas. Indoor environments with coal combustion emissions showed relatively higher oxidative potential and inflammation. Moderate (phenanthrene) to strong (acenaphthylene and benzo(a)pyrene) correlations were observed between selected PAHs against interleukin 6 (IL-6), 8-hydroxy-desoxyguanosine (8-OHdG), and necrosis factor-α (TNF-α). Moreover, 9-fluorenone, 9,10-anthraquinone, and 5,12-naphthacenequinone exhibited higher oxidative stress and inflammation than did their parent PAHs. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV 1) were negatively correlated with 8-OHdG, and FEV 1 /FVC was negatively correlated with TNF-α and IL-6. These findings—which integrates PM 2.5 with lung function and bioreactivity analyses—suggest that coal burning, especially indoors, could elevate the cytotoxicity of PM 2.5 to the occupants and that chronic exposure may lead to a decline in lung function. • PCAs levels were higher in outdoor than indoor and higher in urban than in suburban. • Urban areas and indoor with coal burning showed higher PM 2.5 -induced inflammation. • Correlations were observed between selected PAHs with 8-OHdG, IL-6 and TNF-α. • Lung function was negatively correlated with DNA damage and inflammation markers. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) in urban fugitive dust, known for their toxicity and ability to generate reactive oxygen species (ROS), are a major public health concern. This study assessed the spatial distribution and health risks of 15 PAHs in construction dust (CD) and road dust (RD) samples collected from June to November 2021 over the cities of Tongchuan (TC), Baoji (BJ), Xianyang (XY), and Xi'an (XA) in the Guanzhong Plain, China. The average concentration of ΣPAHs in RD was 39.5 ± 20.0 μg g−1, approximately twice as much as in CD. Four-ring PAHs from fossil fuels combustion accounted for the highest proportion of ΣPAHs in fugitive dust over all four cities. Health-related indicators including benzo(a)pyrene toxic equivalency factors (BAP TEQ), oxidative potential (OP), and incremental lifetime cancer risk (ILCR) all presented higher risk in RD than those in CD. The multilayer perceptron neural network algorithm quantified that vehicular and industrial emissions contributed 86 % and 61 % to RD and CD BAP TEQ , respectively. For OP, the sources of biomass and coal combustion were the key generator which accounted for 31–54 %. These findings provide scientific evidence for the direct efforts toward decreasing the health risks of fugitive dust in Guanzhong Plain urban agglomeration, China. [Display omitted] • Fossil fuels combustion was the dominate source to PAHs in fugitive dust. • Monte Carlo simulated that dermal contact in dust was the main exposure pathway for human health risks. • Vehicle exhausts were the main source to RD BAP TEQ while industrial-related sources were dominated in CD BAP TEQ. • Biomass and coal combustion promoted the dust oxidation potential (OP) generation. [ABSTRACT FROM AUTHOR]

[Display omitted] Atmospheric PAHs (polycyclic aromatic hydrocarbons) and their derivatives are a global concern that influences environments and threatens human health. Concentrations of 52 PAHs and the main derivatives in six Chinese megacities were measured in the winter of 2019. The concentrations of ∑PAHs (sum of 52 PAHs) ranged from 19.42 ± 7.68 to 65.40 ± 29.84 ng m−3, with significantly higher levels in northern cities (Harbin [HB], Beijing [BJ], and Xi'an [XA]) than southern ones (Wuhan [WH], Chengdu [CD] and Guangzhou [GZ]). Source apportionment of ∑PAHs was conducted by the PMF model and results showed coal combustion and traffic emissions were the two dominant sources, which dominated ∑PAHs in northern and southern cities, respectively. Biomass burning was also characterized as a crucial source of ∑PAHs and showed extremely high contributions in XA (42.5%). Assisted by the individual PAH source apportionment results, the source-depend TEQ (total BaP equivalent) and incremental lifetime cancer risk (ILCR) were firstly reported in these cities. The results highlighted the contributions of coal combustion and biomass burning to both TEQ and ILCR, which were underestimated by ∑PAHs source apportionment. Secondary organic aerosol-derived PAHs were demonstrated to increase the TEQ compared with the fresh PAHs and three parameters, namely temperature, relative humidity, and O 3 concentrations were characterized by multiple linear regression as the principal factors influencing secondary reactions of PAHs in winter. This study provides accurate human health-orientated results and potential control measures to mitigate the toxicity of secondary formed PAHs, and significantly decrease the uncertainty level of traditional methods. The results also revealed great progress in air pollution control by the Chinese government in the past 20 years, but still a long way to go to formulate strict emission control strategies from both environmental and human health-protective perspectives. [ABSTRACT FROM AUTHOR]