Diffusion Characteristics Of Particles And Pollutants Under The Closed And Open Space

Air quality has increasingly been a great concern all over the world,and the good command of indoor and outdoor air qualities is of benefit to the air pollution alleviation by various measures.As a major resource of air pollution in urban area,the motor vehicle exhaust has attracted more and more attentions due to its growing amount.It is of benefit to the pollutant control to make clear the transportation characteristics of vehicle exhausts.In this work,the Portable Aerosol Spectrometer was adopted to measure the particle number concentration and size distribution,the air quality monitoring system was used to monitor the gas pollutant concentration,ambient temperature,humidity and other meteorological data.The results are shown as follows:The indoor and outdoor particle concentration distributions of a typical meeting room during haze and clear-sky days were measured.The results show that the mass concentrations of the indoor and outdoor PM₁?PM_2.5?PM₁₀ in heavy haze day are 114±1.8,135.5±3.2,161.7±12.8?g/m3 and 146.4±8.4,192.3±10.2,431.4±34.8?g/m3 respectively,corresponding to 39.3±1.5,58.5±2.5,127.9±10.5?g/m3 and 54.5±4.0,77.8±6.0,173.4±21.6?g/m3 in clear-sky days.Both in the haze and clear-sky days,the number distribution of particles reaches its peak value at the diameter of 0.25?m,but the particle number concentration in the haze day is two times greater than the clear-sky day.The indoor particle concentration is not uniform with the peak value at the corner,which can be effectively alleviated by the air cleaner.The transportation characteristics of vehicle exhaust pollutants are investigated by means of the on-site measurement based on a typical Beijing expressway-Badaling expressway?G6 state expressway?.The concentrations of CO?NOx?SO₂ and particles near the expressway were obtained,by which the variations of the particle number and mass concentrations,as well as the gas pollutant volume concentrations in the vicinity of the roadways with the distance from the expressway were fitted.The results show that the gas pollutant concentrations and particle concentrations decrease almost exponentially with the distance from the expressway.