| In this study, hospitals were selected to investigate and their indoor PM2.5/PM10 were focused on. This is based on three considerations. Firstly, hospital is regarded as a special and important type of public place in China. The number of people is much higher in hospital every day than in other public places. Therefore, effect of hospital IAQ to people is more significant than other public places. Secondly, epidemiological studies showed hospital-acquired respiratory system infection (HARSI, refer to diseases infected from hospital) is well affinity with hospital indoor aerosol which is the carrier for germs and virus diffusion by adhering to aerosol particles. Thus, assessment of PM10 and PM2.5 levels assumes significance from epidemiology. Finally, there are few studies that focused on the indoor air quality of hospitals and few measurements for particulate matter and their chemical composition in hospitals are available in China. The sources and loading of RP in hospitals are presently poorly known. Therefore, our study aimed to: (1) characterize the indoor RP concentrations and associated chemical species in hospitals, (2) investigate the potential indoor sources and (3) assess PM2.5 exposure to hospital human health risk.Indoor air PM2.5 and PM10 samples were collected at the different types of indoor environment in the four hospitals and their adjacent outdoor environments in Guangzhou, China during the summertime, and their associated chemical species including OC/EC, water soluble ions, elements, PAHs were also quantified. The results reached the following conclusions:(1) Hospital indoor and outdoor particulate pollution in Guangzhou was severe and their PM2.5 concentrations were over the standard limit (65μg/m~3, USEPA) by 85.9% and 87.5, respectively. Indoor fine particles were richer than outdoors. The contribution of PM2.5 to PM10 reached 70～83%. Therefore, the human health risk of hospital indoor PM2.5 was higher than outdoors.(2) Indoor PM2.5 and PM10 were well correlated with outdoors (R~2 = 0.81～0.98), indicating that indoor PM2.5 and PM10 were significantly affected by outdoors. In addition to outdoor factors, indoor ventilation types and human activities also contributed to indoor particulate levels.(3) Carbonaceous species (OC and EC) were main components in hospitals indoor and outdoor particles. The TC accounted for 40～58% of PM2.5 mass. 80-94% of OC and 74-94% of EC were found in PM2.5 fraction. The indoor OC levels were 1～3 times higher than outdoors, indicating indoor OC pollution was very severe. All the OC/EC ratios were higher than 2, showing the presence of secondary OC (SOC). The I/O ratios of SOC were over 1, while those of FOC and EC were less than 1.(4) Hospital indoor and outdoor water soluble ions contributed to particles with a high percent of 24.4～45.0%. The sulfates were most important component of the secondary aerosol and they presented in form of ammonium-sulfate in hospitals, but contribution of nitrate to secondary aerosol was much limited. Except the hospital of SJ, the acidity of indoor air was lower than outdoors in observed hospitals. There were good correlations between indoor and outdoor for sulfate, nitrate and ammonium, indicating indoor ions were mainly derived from outdoors. But high I/O ratios of ions also show the impact of human activites.(5) The contribution of total elements to PM2.5 and PM10 mass was 3～10%. Levels of Na, Mg, Al, K, Ca, Zn and Pb were significantly higher than other elements, which accounted for 90% of total elements mass. 18 elements could be classified into two groups according to their sources: crustal elements (Na, Mg, Al, K, Ti and Mn) from natural sources and trace elements (Zn, Cd, Sn, Pb, As, Se, V, Cr, Ni, Cu) from anthropogenic sources. Crustal elements were found in coarse particulate fraction, while anthropogenic elements in fine fraction. The analysis of richment factor (EF) indicated that anthropogenic elements possessed considerably high EF values (100～10000), compared with crustal elements (EF < 20). There was no significant difference between indoor and outdoor for elements (p value > 0.5, T-test), indicating that hospital indoor elements came form outdoor penetration. The factor analysis show that the main sources of elements were natural dust and vehicle exhaust.(6) Indoor and outdoor 3～4-ring PAHs contributed to∑PAHs mass with a low percent and their concentrations were not significant different in all observed hospitals, while for 5～7-ring PAHs, their contributions to∑PAHs were relatively high (45～80%) and the difference of their concentrations in all hospitals were significant. The diagnosis ratios of PAHs indicated that they mainly originated from diesel vehicle exhaust and coal combustion. I/O ratios and factor analysis showed that factors of indoor-to-outdoor penetration, indoor particulate resuspension and gas-particle partion could influenced indoor PAHs levels.(7) The involved exposure assessment of PM2.5 to hospital persons indicated that person's exposure levels to PM2.5 were arranged in order: in-patients > doctors > out-patients. Potential doses of PM2.5 for patients were obviously lower than exposure levels, while for doctors, the differences were not significant. The average applied doses of PM2.5 to patients were found to be much higher than doctors. |
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