[Measurement Analysis and Superposed Effect of Residential Indoor Air Pollutants in Xi'an].

To understand the levels of indoor air pollution and protect public health, our research group conducted monitoring of the concentrations of indoor pollutants (formaldehyde, benzene, toluene, xylene, total volatile organic compounds (TVOC), n-butyl acetate, ethylbenzene, styrene, and undecane) and a health effect assessment for 830 households of Xi'an City from December 2017 to December 2020. Simultaneously, the superposed effect of pollutants was analyzed. The results showed that the exceedance rates of formaldehyde, benzene, toluene, TVOC, and xylene were 92.1%, 39.7%, 11.7%, 8.9%, and 1.2% respectively, among which formaldehyde was the most serious pollutant. There was no significant difference in pollutant concentration and exceedance among different room types. The concentration of pollutants was the highest in summer due to the influence of temperature, humidity, and other factors. The results of the human health risk assessment showed that there were carcinogenic risks of formaldehyde and benzene for different age groups (children, adolescents, adults, and the elderly); children and the elderly were more at risk, whereas xylene, ethylbenzene, and toluene were at low risk (HI<1). The superposed effect of pollutants showed that superposition between indoor pollutants did exist, resulting in the obvious increase in pollutant toxicity. This study provides data reference and scientific basis for the characteristics and healthy effects of indoor residential pollutants in Xi'an City.

Inflammatory and oxidative stress responses of healthy elders to solar-assisted large-scale cleaning system (SALSCS) and changes in ambient air pollution: A quasi-interventional study in Xi'an, China.

An outdoor solar assisted large-scale cleaning system (SALSCS) was constructed to mitigate the levels of fine particulate matter (PM2.5) in urban areas of Xi'an China, providing a quasi-experimental opportunity to examine the biologic responses to the changes in pollution level. We conducted this outdoor SALSCS based real-world quasi-interventional study to examine the associations of the SALSCS intervention and changes in air pollution levels with the biomarkers of systemic inflammation and oxidative stress in healthy elders. We measured the levels of 8-hydrox-2-deoxyguanosine (8-OHdG), Interlukin-6 (IL-6), as well as tumor necrosis factor alpha (TNF-α) from urine samples, and IL-6 from saliva samples of 123 healthy retired participants from interventional/control residential areas in two sampling campaigns. We collected daily 24-h PM2.5 samples in two residential areas during the study periods using mini-volume samplers. Data on PM10, gaseous pollutants and weather factors were collected from the nearest national air quality monitoring stations. We used linear mixed-effect models to examine the percent change in each biomarker associated with the SALSCS intervention and air pollution levels, after adjusting for time trend, seasonality, weather factors and personal characteristics. Results showed that the SALSCS intervention was significantly associated with decreases in the geometric mean of biomarkers by 47.6% (95% confidence interval: 16.5-67.2%) for 8-OHdG, 66% (31.0-83.3%) for TNF-α, 41.7% (0.2-65.9%) and 43.4% (13.6-62.9%) for urinary and salivary IL-6, respectively. An inter-quartile range increase of ambient PM2.5 exposure averaged on the day of the collection of bio-samples and the day before (34.1 µg/m3) was associated, albeit non-significantly so, with 22.8%-37.9% increases in the geometric mean of these biomarkers. This study demonstrated that the SALSCS intervention and decreased ambient air pollution exposure results in lower burden of systemic inflammation and oxidative stress in older adults.

[Concentration Analysis and Health Risk Assessment of Air Pollutants in Newly Decorated Public Places in Xi'an].

In order to understand the levels of indoor air pollution and health risks in public places, our research group conducted air quality monitoring and human health risk assessments for five types of public places (offices, classrooms, laboratories, banks, and hospitals) in Xi'an City from December 2017 to July 2020. The test items included formaldehyde, benzene, toluene, xylene, n-butyl acetate, ethylbenzene, styrene, n-undecane, and total volatile organic compounds (TVOC). The results showed that formaldehyde had the highest exceedance rate (59.4%), followed by toluene, TVOC, benzene, and xylene. Among the five types of public places, hospitals had the highest rate of pollutants exceeding the standard (46.7%), and the main pollutants exceeding the standard were formaldehyde, benzene, and toluene. The results showed that the concentrations of formaldehyde and TVOC were positively correlated with temperature and humidity. The health risk assessment results showed that there were carcinogenic risks of formaldehyde and benzene in different places; people working in banks had a higher risk of formaldehyde carcinogenesis, and those working in hospitals had a higher risk of benzene carcinogenesis. This study provides a reference for the level of indoor air pollution in public places in Xi'an City, and is of great significance to the health risk research of related populations.

The rural carbonaceous aerosols in coarse, fine, and ultrafine particles during haze pollution in northwestern China.

The carbonaceous aerosol concentrations in coarse particle (PM10: Dp ≤ 10 µm, particulate matter with an aerodynamic diameter less than 10 µm), fine particle (PM2.5: Dp ≤ 2.5 µm), and ultrafine particle (PM0.133: Dp ≤ 0.133 µm) carbon fractions in a rural area were investigated during haze events in northwestern China. The results indicated that PM2.5 contributed a large fraction in PM10. OC (organic carbon) accounted for 33, 41, and 62 % of PM10, PM2.5, and PM0.133, and those were 2, 2.4, and 0.4 % for EC (elemental carbon) in a rural area, respectively. OC3 was more abundant than other organic carbon fractions in three PMs, and char dominated EC in PM10 and PM2.5 while soot dominated EC in PM0.133. The present study inferred that K(+), OP, and OC3 are good biomass burning tracers for rural PM10 and PM2.5, but not for PM0.133 during haze pollution. Our results suggest that biomass burning is likely to be an important contributor to rural PMs in northwestern China. It is necessary to establish biomass burning control policies for the mitigation of severe haze pollution in a rural area.