| Fine particulate matter(PM2.5) has small size, large specific surface area, easy to enrichment characteristics of toxic and hazardous and long-standing in environment, has a large content changes in ambient air.PM2.5 can enter to lungs through breathing and even to heart head blood-vessel and cause serious damage to human body health, so relevant concentration of PM2.5, pollution characteristics,and the crowd exposure risk research received with increasingly wide attention by scholars. Now people in the society with more than 80% of the time is spent indoors, statistics show that PM2.5 concentrations in some ambient air may far more than outdoor, so indoor pollution characteristics of fine particulate matter is more closely related to human health.At present,there were some problem of China urban air,for example the PM2.5 pollution,population exposure and health risk assessment were not clear. The research on PM2.5pollution in air pollution control has become a hot topic,but there were few public indoor PM2.5 pollution characteristics and depth exploration of harm to human. This study obtained the urban population in Guangzhou through questionnaire time- activity patterns and health information, and select the typical indoor micro-environment, analyzes and discusses the typical indoor pollution characteristics and chemical characteristics of fine particulate matter,evaluated the typical polycyclic aromatic hydrocarbons(PAHs) in indoor air by breathing exposure process lead to human body health of the risk of cancer.The main conclusions are as follows:1. According to the result of recycling questionnaire, combined with the percentage of time spent indoors with survey population, screening to determine the typical indoor environment for monitoring, namely smoking office, printing office, residential, office people,Single offices and laboratories.2. In the research of typical indoor PM2.5 in ambient air concentrations ranging from18.75 to 121.11μg·m-3, outdoor concentration range from 55.09 to 87.04μg·m-3.With a stable weather condition,the weekend outing made a significantly increased to outdoor PM2.5concentrations. The concentration of PM2.5 in smoking and printing office were more than the daily average concentration limit of 1.48 and 1.35,the pollution degree were heavier, It recommended strengthening the ventilation control room source emissions and other measures to reduce pollution.3. Research measured that OC/EC and water-soluble ion were the main composition of PM2.5,and the proportion was larger as 17.27%~41.58% and 6.91% ~23.80% respectively. By OC / EC ratio analysis that laboratory and single offices exist active process of secondary pollution.Water soluble ion of PM2.5 concentrations were 6.91 ~ 23.80%, one of the highest concentrations of SO42- were 20.16 ~ 62.37% of total ion, the sum of three kinds of hydrophilic stronger ion were 77.24 ~ 89.56% of total ion concentration,by good correlation coefficient of SO42-, NO3-, Na+, Cl-, K+analysis that they may come from the same stationarysources.4.The average concentration order of metallic elements in indoor PM2.5 as: Fe> Zn> Al>V> As> Mn> Cr> Pb> Se> Sb> Ni> Cd, All the samples As chroma of elements of serious, Pb content is lower than the average concentration limit.Using correlation analysis and principal component analysis showed that Most have obvious correlation between elements,the metal elements were derived from surrounding industrial areas, traffic sources and combustion sources. The concentrations of polycyclic aromatic hydrocarbons in PM2.5 range from 0.38 to8.57ng·m-3, and low-ring PAHs accounted for the vast majority,the Acy, Ace, DahA monomer were detected, and Phe, Ant, BaA, were small amounts of checked out. Through polycyclic aromatic compounds ratio we got a rough judgment that the indoor environment mainly effected with oil and coal combustion sources, the outdoor atmosphere mainly existed coal combustion sources.5. With reference to the EPA recommended toxicity equivalent method measured,in this study, the typical indoor PAHs toxicity equivalent in the range were 0.0004 ng · m-3 to0.6218ng·m-3, and the risk value were acceptable to crowd within 8.12×10-9 to 1.33×10-5.Refer to the manual exposure,we estimated the life expectancy loss caused by PAHs in typical indoor air were up to 82.92 min in printing office and outdoor life expectancy loss were5.67 min.Due to population, area, personal life, eating habits, such as large differences,estimate the results of research may be some differences with the actual situation of our country crowd, this has increased the exposure through breath only lead to uncertainty of lifetime cancer risk assessment, so this study can be regarded as the typical indoor environment in guangzhou in the human body through breathing exposure to PAHs due to preliminary assessment of health risk. |
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