A Typical Dose Evaluation Of Xi'an City Traffic NOx Pollution Characteristics Microenvironment And Exposure

With the increase of economic development and the improvement of people’s living standard of xi’an, motor vehicle ownership increased nearly10times more in ten years, usage rate also increased,which leading to xi’an traffic jam phenomenon more and more serious.Thus causing a high concentration of vehicle exhaust pollutant accumulation in the street and stay longer when people riding in the car. As a result, the car traffic environment is good or bad in quality are becoming more and more closely in the relationship between the traffic environment and people,and gradually become the focus of the people. In this paper, taking the typical pollutants NOx in the traffic micro-environment as the main research object, through the experiment monitoreing, analying and the methods of questionnaire, access to obtain xi’an NOx pollution data within a and population exposure parameter data. Through the data, explored the typical traffic micro space-time distribution characteristics and causes of NOx in the typical traffic micro-environment, and evaluated the size of exposure dose of different age stages of xi’an citizens who exposed in the traffic environment.Based on monitoring results in this paper, the results showed that the daily average concentration of NOx in xi’an six kinds of typical traffic microenvironment of private car, taxi, air conditioning bus, no-air conditioning bus, subway, bus stop respectively are:0.664mg/m3,0.474mg/m3,0.514mg/m3,0.282mg/m3,0.248mg/m3and0.175mg/m3. Research results show that it has an obvious peak in the morning and evening of daily variation, high concentrations of on Monday and Friday in a week, a "valley" season change-Summer and fall lower, spring winter higher in the traffic microenvironment of xi’an.Rain and snow, wind and other special weather, NOx pollution is lighter.In space, on the horizontal direction, the car front is serious polluted than the back of the bus.As far away from the station, the smaller NOx density in the bus station. On the people breathe with different heights, NOX concentration of1.5m is lower than0.8m in the bus station. Lateral comparison research conclusion is:the private cars, air conditioning bus, taxi were the most polluted, the subway environment quality is better. Different ventilation mode, the maximum NOx concentration inside the car when open the window, do not open the window inner loop pollution is relatively small. Research found that the concentration of micro-environment difference is directly related to the number of cars, fuel, ventilation mode, vehicles and other sources, diffusion conditions, the temperature and human activity rules.Reference for the different exposure dose of parameters of xi’an during infant, primary and middle school students and young adults and the elderly the weight of different ages, respiratory rate, exposure time, exposure frequency.exposure to environmental pollutants concentration,etc. Using exposure risk evaluation model, evaluated the exposure dose to different age exposure-crowd. The results are as follows:among people exposed to levels of up to59.78×10-3mg/(kg·d), infants and young children second by32.7×10-3mg/(kg×d), exposure to the lowest levels of primary and middle school students,20.08×10-3mg/(kg×d), center exposure risks for the elderly, upto19.47x10"3mg/(kg-d). the traffic micro-environment quality of subway is the best.This research from technology, traffic planning, government policy and related laws and regulations formulation, citizen consciousness of environmental protection four aspects put forward the control measures to xi’an traffic urban traffic micro-environment. In this paper, the results of the study will lay a foundation for the further research of the urban traffic environment, provide a reference for government department decision-making and the overall urban planning, to alleviate the urban traffic congestion, traffic pollution and improving urban environment quality has the reference value.Which will have positive significance for building of xi’an international metropolis and the physical and mental health of residents.