Study On The Influence Of Garbage Odor Source Location And Balcony Design On Pedestrian-level Exposure Risk In Residential Community

Residential areas are the main places for people to live and rest.With the improvement of residents’demand for quality of life and health,residents have put forward certain requirements for the ambient air quality in their residential areas.The intensification of urbanization has led to the formation of high-density residential buildings,which results in poor ventilation in residential areas.Especially in the hot summer,the household garbage not removed in time will produce harmful odor gas,which makes it difficult to fully diffuse and dilute around the poorly ventilated residential buildings.These malodorous gases accumulate in the dead corner of the residential area,further increasing the exposure risk of residents during outdoor activities.Although there have been some reports and studies on the diffusion of pollutants in residential areas and blocks,most of them are harmful gases（CO,NO_X）from automobile exhaust as pollutants,and there are few quantitative analysis reports on the diffusion of odor produced by wet garbage in residential areas with the wind.Therefore,understanding the source location and diffusion path of municipal solid waste odor in residential areas,as well as the influence of building balcony design on its diffusion and pedestrian exposure risk,can provide technical reference for measures to reduce municipal solid waste（MSW）odor harm to residential residents’health.This study is mainly carried out from the following four aspects:1)A community in southwest Shanghai was selected as the test site,and this study analyzed the factors affecting the change of odor concentration by testing the odor concentration generated by domestic garbage in the residential area and the surrounding environmental parameters.The test results in this study show that the concentration of methanethiol（CH₃SH）produced by domestic garbage in this residential area is higher than that the concentration of hydrogen sulfide（H₂S）,and the change of odor concentration is related to the waste content,wind speed and temperature.However,compared with CH₃SH,H₂S is the main odor contributors,so this paper chooses H₂S as the tracer gas for the subsequent simulation study.2)The RNG k-εturbulence model was used to simulate for the computational fluid dynamics（CFD）.By comparing the simulation results with the wind tunnel test results,it is found that the simulation results are in good agreement with the wind tunnel test data,which indicates that the RNG k-εmodel and numerical method are suitable for predicting the windborne diffusion of odor in the residential area and can be applied to the simulation of the subsequent cases in this study.3)Taking the typical residential areas in Shanghai as the object of field research,it is found that the waste collection points are generally located the corner of the building array’s periphery,the middle of the array’s periphery,and between two adjacent buildings in the center of building array.On this basis,simplified modeling of residential buildings was used to simulate the concentration distribution of the odor around the building array when the source is in five different locations,so as to obtain the location of the collection point in the residential area is less affected by high concentration pollutants.The results showed that the odor concentration distribution and exposure risk of residents in residential areas are easily affected by the location of the waste collection points.When the collection point is at the corner of the building array’s periphery,the local dimensionless concentration of H₂S in the pedestrian area was lower and the average personal intake fraction（）was lower than 3 orders of magnitude when it is located the middle of the array’s periphery or between two adjacent buildings in the center of building array.4)The influence of balcony design and the presence of upstream buildings on the diffusion of pollutants from different source locations in residential areas were investigated,and thewas used to assess the exposure risk of residents.The study indicates that the balcony design can effectively reduce the distribution range of the high concentration of H₂S and the average dimensionless concentration of H₂S in residential pedestrian area and between the building street canyons,and also reduce thevalue in the pedestrian area,which reduces the exposure risk of outdoor residents.At the same time,although the presence of upstream buildings of the inflow flow can reduce the diffusion range of high concentration H₂S produced in the source location between two adjacent buildings in the center of building array,it is not conducive to the rapid diffusion of high concentration H₂S when the odor source is located in the middle of the array’s periphery.