The Investigation On The Diffusing Mechanism And Prevention Of Inhalable Particulate Matter In The Roadside Residential District

With the rapid development of China’s urbanization and the increase of carownership，urban roadway air pollution problem has become increasingly prominent.Inhalable particulate matters become main pollutant which has a great influence onambient air. Deterioration of the urban roadway air can not only influence outside airquality, but inside air quality of the roadside buildings. Greening has an important rolein Dust detention effect, which is an significant measures to improve the environment.Residential districts are important settlement and places for residents, in which the airquality closely linked with human life and in the area seriously polluted. Thus, it isnecessary to study the diffusion regularity of PM10in the residential district, anddiscuss the effects of different greening types to the PM10distribution.The article proposed some methods which add the source term in the greeningareas by analyzing the particle and settlement mechanics, and built pollutant diffusionmodels considering the role of the absorption of PM10by trees. A roadside residentialdistrict was chosen to test, and the effectiveness of the proposed algorithm was verifiedby the comparison results. The effect of gravity and wind speed on PM10diffusion wasstudied using numerical simulation. Found on this, the effect of gravity and differentgreening patterns on PM10diffusion was studied, and compared with the PM10diffusion without greening. At the same time, the PM10diffusion with greening wasstudied, and analyzed the effects of different greening types to the PM10distribution,focusing on the purification percentage of PM10.The approximation of numerical resulted to the spot test results demonstrates the effectiveness of the proposed model. Considering the gravity or not had little effect onthe concentration distribution. At the same point PM10concentration decreased with theincrease of the height,8m above the ground, PM10concentration of each point closedto zero. The maximum PM10concentration was near ground closely to roadside, whileit didn’t appear to be much different around the building. Under a definite winddirection, spreading range of PM10would expand as the wind speed becomes greater.Decline rate of PM10concentration increased with wind speed increases during thesame distance. Single row trees caused a15.1%decrease, and single row shrub17.1%compared with no greening. The dust blocking effect of shrub was superior to trees, theaverage PM10removal percentage was increased3.31%. The dust blocking effect oftwo row trees was superior to single row trees, two row trees type causes a11.9%decrease, tree-shrub type causes16.7%decrease, and shrub-tree type causes18.6%decrease. The dust blocking effect of shrub-tree type was the best, and PM10removalpercentage increased8.66%and3.92%compared with two row trees type andtree-shrub type.