PM_2.5 Indoor And Outdoor Pollution In Tianjin: Characterization And And Influencing Factors

Fine particulate matter(PM2.5) pollution has been one of the most primary atmospheric pollutants at present in China. Because of its potential harm to human body, it has been identified as carcinogens by International Agency for Research on Cancer(IARC). Considering the fact that people spent about 80% time indoors per day, PM2.5 indoor pollution and its relations with outdoor pollution have caused wide attention at home and abroad. As a large city, Tianjin is growing fast and has high population density, so it is very important to study PM2.5 indoor and outdoor pollution in Tianjin. In order to understand PM2.5 indoor and outdoor pollution characteristics and the effect of weather conditions on it, we monitored atmospheric PM2.5 concentrations and collected samples in the heating season since November, 2013 in Nankai and Beichen districts of Tianjin. In addition, indoor and outdoor PM2.5 were monitored and collected in the offices and residential rooms of Nankai and Beichen districts from April to June in 2014, as well as the corresponding meteorological data. PM2.5 pollution characteristics and its influence factors were studied further by using ion chromatograph and thermal light carbon analyzer. The main contents and innovative points are summarized as follows:1. The indoor and outdoor PM2.5 mass concentrations were monitored in Tianjin. Then the spatial and temporal variation characteristic of outdoor PM2.5 mass concentration was analyzed. Moreover, correlation and delay time of indoor and outdoor PM2.5 mass concentrations distributed in 4 different indoor places located in urban and rural. Meanwhile, the effect of meteorological factor on atmospheric PM2.5 mass concentration and I/O ratio were analyzed based on the synchronous meteorological data, such as temperature, humidity, air pressure, wind speed, wind direction, rainfall, etc.2. The water soluble ion contents in indoor and outdoor PM2.5 was studied, involving the spatial and temporal distribution characteristic of outdoor PM2.5 water soluble ion content. Then the change features of indoor and outdoor PM2.5 water soluble ion contents were investigated for 4 indoor sample places in urban and rural. Furthermore, the correlation of ion concentration between inside and outside was studied and the possible ways of composition of water soluble salt components were confirmed via calculating the different ion correlation in different time and different places.3. The concentrations of organic carbon(OC) and elemental carbon(EC) in indoor and outdoor PM2.5 were measured. Simultaneously, the spatial distribution characteristic of OC and EC in PM2.5 was summarized. Some analyzing methods including linear regression, correlation analysis and so on were applied to explore the interrelation of carbon fraction between inside and outside. Besides, the second organic carbon(SOC) content was estimated. In order to further analysis the carbon sources of indoor and outdoor PM2.5, principal component analysis(PCA) was used for the eight elements of carbon fraction and the differences of carbon sources discussed.