Influencing Factors And Prediction Model Of PM2.5 Concentration In Office Buildings

Particulate matter in the air can do harm to human health and affect atmospheric visibility,among which epidemiological and toxicological studies have shown that population mortality and the incidence of various diseases are closely related to the concentration of particulates in the air.At present,the atmospheric haze pollution of the grim situation makes the pollution of particulate matter management without delay,compared with the outdoor environment,the control of indoor air particles is more urgent,because there are more than 80% of the time are spent in a limited space in the room for people,indoor air quality has greater impact on people’s health than ambient.Therefore,in the main pollutants the PM2.5 is regarded as the research focus,to start on the indoor and outdoor PM2.5 concentration between the correlation and indoor PM2.5 concentration factors related to research,is conducive to improve the indoor air quality and reduce the indoor staff of the risk of exposure to contaminants.In this article,the air quality monitoring platform is used to know the air pollution situation in the main city of Chongqing.Taking an office building in Shapingba District of Chongqing as the object of study,the PM2.5 daily average concentration of indoor and outdoor are monitored under different forms of air conditioning types in summer,and the indoor,outdoor PM2.5 concentration and kinds of environment parameters are measured under different ventilation condition and different indoor PM2.5 dispersion source in winter.The correlation between PM2.5 concentration in indoor and outdoor is determined by correlation analysis.PM2.5 concentration and influencing factors are confirmed,and the specific PM2.5 concentration control measures are put forward.Finally,the indoor PM2.5 concentration is evaluated and the prediction model of PM2.5 concentration is put forward according to the mass balance equation.And the accuracy of the model prediction is proved by using the measured data.The main results and conclusions of this paper are:(1)The daily average PM2.5 concentration of Chongqing’s office building in the centralized air conditioning,split air conditioning and non air conditioning office rooms is 86.3μg/m3,74.0μg/m3 and 100.8μg/m3 respectively,the value of I/O ratio is 0.96,0.59 and 0.81,respectively,and the correlation coefficients is 0.94,0.77 and 0.92,respectively.The correlation between indoor and outdoor PM2.5 concentration is related to the form of air conditioning system.Among those conditioning forms under discussion,the most significant is under the type of centralized air conditioning,and when under split air conditioning,with minimum correlation.(2)In winter,the indoor PM2.5 concentration in Chongqing which are under window opening,window closing and air conditioning opening is 81.0μg/m3,71.2μg/m3 and 81.6μg/m3,respectively,and the value of I/O ratio is 0.96,0.82 and 0.69,the correlation coefficients is 0.91,0.72 and 0.69 respectively.The concentration of PM2.5 in the room is 70.9 ± 2.8μg/m3,150 ± 9.1μg/m3,207.3 ± 8.8μg/m3 respectively when there is no obvious,mild and moderate PM2.5 emission sources.The concentration difference of PM2.5 in indoor and outdoor is-15.8μg/m3,36.2μg/m3 and 95.5μg/m3,respectively;According to hourly variation diagram of indoor and outdoor PM2.5 concentration,the delay time tdy of indoor and outdoor PM2.5 transmission process under different indoor environment was obtained.(3)In the correlation analysis of winter,for the office building in Chongqing the environmental parameters related to the indoor PM2.5 concentration are: indoor and outdoor temperature,indoor and outdoor relative humidity and outdoor wind direction when the window is open;indoor and outdoor temperature and humidity when the air conditioner is turned on;indoor temperature,outdoor temperature,outdoor relative humidity and outdoor wind direction;low emission source intensity,the parameters are not significant;indoor moderate distribution of the source when there is room temperature and relative humidity.(4)According to the influencing factors of indoor PM2.5 concentration,the control measures of PM2.5 concentration for window opening,window closing,air conditioning opening,indoor low and moderate PM2.5 emission source are put forward,which can effectively reduce the indoor PM2.5 concentration,so as to ensure the health of the staff in the office.(5)Based on the measured indoor PM2.5 concentration and residence time in the interior of indoor environment,the average synthesis exposure amount for PM2.5 of personnel 1and 2 is 78.5μg/m3 and 78.6μg/m3 respectively.The respective mean dose of ET,BB and AI for office-holder 1 is 409.91μg,248.69μg and 108.62μg,for office-holder 2: 421.37μg,255.78μg and 117.5μg.Based on the indoor PM2.5 mass balance equation and the factors related to the indoor PM2.5 concentration determined by the correlation analysis,the prediction model of indoor PM2.5 concentration was put forward when the window is closed and there is no obvious dispersion in the room.The accuracy of the model in indoor PM2.5 concentration prediction was verified by data analysis.