Exposure Assessment Of Fine Particulate Matter(PM_2.5) For The Typical Sub-population In Guangzhou City

In recent years, while the rapid development of industrialization and urbanization hasimproved the living conditions of the citizens in Guangzhou, the accompanying degradationof local air quality, especially atmospheric fine particulate pollution, has also arousedwidespread concern. Epidemiologic studies have shown that long-term exposure to PM_2.5has enormous impacts on human health. Compared to ambient concentrations and exposureconcentrations, the potential population exposures to PM_2.5have more direct associationswith human health. Meanwhile, in-depth understanding of human exposure to atmosphericparticulate matter is essential for policymaking and for development of risk reductionmeasures. Up to now, there have been few studies reported to estimate potential populationexposures to PM_2.5and its compositions in Guangzhou.Accordingly, we chose the residents located in the downwind area of a steel plant,pupils and university students as the study objectives in Guangzhou, investigated theirtime-activity patterns and basic personal information, monitored indoor and outdoor PM_2.5simultaneously in typical microenvironment where people activated, analyzed chemicalcomposition in PM_2.5, identified the pollutant sources of indoor and outdoor PM_2.5, assessedpotential exposure doses of PM_2.5and chemical components, and discussed influencingfactors of the potential exposure doses of PM_2.5.The main results were shown as follows:（1）Built basic database on time-activity patterns and personal information of typicalsub-population in Guangzhou.（2）Monitored indoor and outdoor concentrations of PM_2.5and I/O values in typicalmicroenvironment where people activated, and identified the sources of indoor PM_2.5. Theresults showed that it was highly polluted in every typical microenvironment in Guangzhou;ventilation had a great influence on indoor PM_2.5, while population density and generalactivities had small influences on indoor PM_2.5.（3）Analyzed chemical components of PM_2.5in the elementary school （close to trafficarteries） and the community （in the downwind area of a steel plant）, and identified the sources of outdoor PM_2.5. The results indicated that high PM_2.5concentration in thecommunity was possibly due to the upwind industrial emission sources, while PM_2.5concentration in the elementary school was influenced by mobile emission sources nearbyand regional industrial emission sources. The average OC/EC ratios indicated the possiblepresence of secondary organic aerosols in both sampling sites. Strong OC-EC correlationssuggested that the emissions of OC and EC were likely attributed to common emissionsources. The average NO3-/SO₄^2-ratios suggested that stationary sources were significantcontributors to atmospheric particles.（4）Based on PM_2.5mass concentrations and chemical components in typicalmicroenvironment, time-activity patterns of targeted sub-population, and inhalation ratefrom literatures, we assessed potential exposure doses and exposure concentrations of PM_2.5for typical sub-population, and identified various activities and microenvironmentcontributing to potential exposure doses. The results showed that the potential exposuredose and daily exposure concentration of PM_2.5for the university students were smaller thanthose for the downwind residents, but greater than those for the pupils. The daily exposureconcentrations of PM_2.5for the university students and downwind residents both exceededthe24-h limits of Ambient Air Quality Standard for PM_2.5. Daily averaged potentialexposure doses of POM and SO₄^2-for the residents in the community and pupils at schoolwere much larger than those of other chemical components in PM_2.5.（5）Investigated influencing factors of the potential exposure doses of PM_2.5usingSpearman rank correlation analysis.