Numerical Simulation Study Of Urban Road Sweeping On The Concentration Of Atmospheric Suspended Particulars

Atmospheric suspended particulate is a primary air pollutant in the world.Especially,inhaled particulate matter has been regarded as a pollutant resulting in adverse effects on the human health,environment and climate.In most cities of our country,road sweeping is manual and causes secondary fugitive dust.Those particulates result in repeated pollution and may cause negative effects on passers-by and residents.The distribution characteristics of atmospheric suspended particulates in campus far from the road traffic and three typical urban road: street canyon,open roads,one side open roads were measured with Dustmate at different heights?1.5 and 1m?in Hefei city and then simulated with RANS ke modeling.The results are as follows:?1?Concentration of typical urban roads atmospheric suspended particulates takes markedly diurnal variation feature.The daily distribution characteristics of atmospheric suspended particulates were higher at night than at noon.?2?Road sweeping might be one reason of the particulate concentration peak during the day.Site observation during road sweeping showed that the street canyon concentrations of PM₁₀ and TSP were about 5000 ?g/m³,which was higher than the open roads and one side open roads.Sweeping causes two peaks of particulate matter concentration.One of the reasons is sweeping,and the other by the cleanup of stacked rubbish.The impact of urban road sweeping on atmospheric suspended particulates should not be neglected.?3?Generally speaking,the concentration of TSP and PM₁₀ at 1 m is higher than that of 1.5 m.The PM₁₀ concentration played a main role in affecting the value of TSP in the air of traffic roads.More over,PM₁₀ and TSP concentrations in the air of typical roads had positive linear correlations in different high.?4?Results of the numerical simulation show that PM₁₀ concentration has a peak during sweeping.PM₁₀ is relatively low at first.But it rapidly increases when sweeping,and then drops at different high of three typical roads.?5?Further three-dimensional numerical simulations indicate that under the influence of weak wind along the street,in a time interval of 30 s,road sweeping brings up a pollution zone about 30x3 square meters.The pollution zone grows short as wind gets stronger,but change little in its width.This study shows that road sweeping results in a wide pollution zone whose PM₁₀ is over State Standard 2012 2^nd class standard,and its center over even20 times,thus being great potential to human health.We suggest based on this study that road sweeping should be avoided as possible as it can be.