Emission characterizations from major indoor sources and carbonyls investigation in four Chinese mega-cities

People spend 80-90% of their time indoors, so exposure during time spent indoors can account for most of the total personal exposure of people to these pollutants. With the recent rising environmental and health awareness, people are paying more attention to the quality of indoor air. Due to the fact that many indoor activities generate toxic air pollutants (TAPs), indoor concentrations of many volatile organic compounds (VOCs), and carbonyl compounds are found substantially higher than outdoors. VOCs and carbonyl compounds are emitted from building materials, furnishings, indoor combustion (incense burning, smoking, mosquito coils burning, etc.) and consumer products. The release of air pollutants from these sources can adversely affect the indoor air quality and the 'well being' of occupants. In order to correctly characterize the indoor air quality, emissions from a variety of sources, including building materials, and indoor combustion activities, must be considered. The main objective of this research project is to both characterize the emissions from common indoor sources and investigate the carbonyls levels in indoor environment in four Chinese mega-cities. The emission experiments of major indoor combustion activities including burning of incense, mosquito coils, and candles, and cigarette smoking are carried out in a large environmental chamber. The carbonyl compounds emissions from architectural coatings are also carried out in a micro-environmental chamber. The air pollutant levels in temples during peak and non-peak periods are characterized. In addition, the indoor and outdoor carbonyls levels in dwellings in four Chinese mega-cities (Beijing, Shanghai, Xi'an, and Guangzhou) are investigated. Finally, a chemical mass balance (CMB) receptor model is adopted to identify sources apportionment of carbonyls species. The emission data obtained in this study could be used to estimate the population exposure to the target air pollutants emitted, and to reduce the exposure through proper selection of indoor materials such as incense, candle, mosquito coil, cigarette, and architectural coating or by avoiding certain indoor combustion activities. The results will also advance general knowledge of the carbonyl compounds levels in dwellings. The control of these carbonyls would lead to reducing the health risks of building occupants.