| Volatile organic compounds (VOCs) are important air pollutants in theatmosphere, which have been known as major precursors in the formation ofphotochemical smog and ground level ozone as well as primary health riskfactor in both indoor and ambient air. Therefore, the study of exposurecharacteristics, environmental health effects and source apportionment of VOCsin ambient air pollution are of great significance. Presently, related research havebeen conducted in many domestical and international urban areas, but notinclude Taiyuan, so this paper designed to study the human exposurecharacteristics of atmospheric VOCs in public places in Taiyuan with the majorresults are listed below:1. A total of55species of VOCs were monitored by using SUMMA canistersfor air sampling, and Entech7100-Agilent7890A gas chromatography/5975Cmass selective detector (GC-MSD) for analyzing, including alkanes (55.18%),aromatics (28.07%), alkenes (12.72%) and alkynes(4.03%). The averageexposure level of the total VOCs of the target compounds was89.37μg/m3inTaiyuan, while the exposure level of benzene (6.49μg/m3) had exceeded theannual concentration standard (5μg/m3) required by the European Communityby nearly1.30times, which is also higher than that in many domestic andforeign cities. The highest and lowest VOCs exposure levels were found inChildren Park and Fenhe Park, respectively. The difference may attribute to thedifferent geographic characteristics of the two places. Children Park is located inthe largest business district in Taiyuan, and surrounded by dense constructions,which severely prevent the dispersion of air VOCs pollutants, while the openterrain of Fenhe Park benefit their spread. The concentration of VOCs in thenight was higher than the daytime, and higher at weekends than workdays infive parks, reflecting the influence of human activities on the exposure level ofVOCs in the atmosphere. The seasonal variation of total VOCs indicated that theconcentrations of VOCs were73.69、79.56、72.99and63.18μg/m3in January,May, September and December, respectively. The annual variation of total VOCs indicated that the concentration in2013was lower than2012, whichindicating that a series of pollution control measures adopted by the Taiyuangovernment for improving the air quality are very effective.2. Based on the internationally recognized four-step evaluation model ofhealth risk assessment, volatile pollutants would not cause non-carcinogenichealth to the exposed population on the workdays and weekends. It isnoteworthy that the benzene associated cancer risk at weekends was1.29×10-6,which exceeded its carcinogenic threshold suggested by US EPA and may causepotential harm to human health. Then both maximum incremental reactivity（MIR）and equivalent propylene concentrations were used to estimate theVOCs ozone formation potential(OFP). The results showed alkenes were thelargest contributions to the OFP among all kinds of VOCs, followed byaromatics and alkanes.3. From the results of correlation analysis, concentration ratios and principalcomponent analysis, the VOCs pollutants in Taiyuan were mainly contributed bycoal combustion, vehicle exhaust emissions, industrial process and solvent usage.It could be seen from the back trajectories that air VOCs pollution in Taiyuanwas major from the emission of local plants (Thermal power plants, Taiyuansteelworks, Cement plants) and the small-scale atmospheric transmission fromperipheral coking plants in Taiyuan Basin.Our study enriches the Shanxi local databases of environment pollution statusand human health risk factors, which will contribute to governmentdecision-making and targeted pollution control. |
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