Air pollution dispersal in high density urban areas: Research on the triadic relation of wind, air pollution, and urban form

Yang, Junyan; Shi, Beixiang; Shi, Yi; Marvin, Simon; Zheng, Yu; Xia, Geyang

doi:10.1016/j.scs.2019.101941

Cited by 175 publications

(64 citation statements)

References 30 publications

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“…Among the urban microclimate elements, solar radiation and ventilation (through atmospheric wind conditions [16]) are significantly affected by the vertical urban form. High-rise buildings obstruct sunshine and wind, therefore, heat and hazardous substances cannot evaporate smoothly, causing the increase of air temperature [17,18]. In terms of building density, a compact building layout obstructs the incoming wind, reducing the wind speed and affecting the urban thermal environment [19].…”

Section: Introductionmentioning

confidence: 99%

“…The variation of building height affects the sunshine and shadows inside street blocks, changing the urban near surface temperature [22]; an extremely high building density slows down the near surface airflows, causing poor ventilation [19]. Consequently, not only air circulation and pollutant dispersion, especially in the near surface region [10,18] are obstructed [23], but also the urban climate and heat island effect are affected [24,25], which eventually leads to the loss of self-regulation ability of an urban ecosystem.…”

Section: Introductionmentioning

confidence: 99%

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Impacts of Urban Form on Thermal Environment Near the Surface Region at Pedestrian Height: A Case Study Based on High-Density Built-Up Areas of Nanjing City in China

et al. 2020

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The continuous worsening of urban thermal environments poses a severe threat to human health and is among the main problems associated with urban climate change and sustainable development. This issue is particularly severe in high-density built-up areas. Existing studies on the thermal environments (temperature data extracted from satellite remote sensing images) are mainly focused on urban canopy areas (airspace below the average height of trees or buildings) rather than the near surface region (at pedestrian height). However, the main outdoor activity space of urban residents is the area near surface region. Hence, this study aims to investigate the influence of urban form (i.e., building density, height, and openness) on thermal environment near the surface region. The high-density built-up areas of a typical megacity (i.e., Nanjing) in China were selected, and the thermal environments of 26 typical blocks were simulated using ENVI-met software. Temperature field measurements were carried out for simulation validation. On this basis, a classified and comparative study was conducted by selecting the key spatial form elements that affect thermal environments. The results showed that in actual high-density built-up areas, single urban form parameter does not determine the thermal environments near the urban surface but mainly affected by the use (function) of space. For this study, the overall thermal environment of a street block is optimal when the building density is between 40% and 50% and the average building height is between 8 and 17 stories. Nonetheless, the urban form can be improved to optimize the overall effects on building functions and thermal environments. Furthermore, function-specific urban form optimization strategies were proposed to optimize thermal environments according to specific functional needs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impacts of Urban Form on Thermal Environment Near the Surface Region at Pedestrian Height: A Case Study Based on High-Density Built-Up Areas of Nanjing City in China

et al. 2020

Self Cite

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“…The result in this paper indicates that average wind speed seems to lead to high PM10 pollution. The difference can be explained by the incomparability of high-rise buildings in high density cities [ 58 ]. For cities with larger population sizes, building heights in these high-density cities are greater, which may explain why high wind speed does not lead to a good PM environment, as this may be influenced by an increase in high-rise buildings.…”

Section: Discussionmentioning

confidence: 99%

Can the New Subway Line Openings Mitigate PM10 Concentration? Evidence from Chinese Cities Based on the PSM-DID Method

Wang

Tao

Wang

et al. 2020

IJERPH

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The large-scale construction of subway systems, which is viewed as one of the potential measures to mitigate traffic congestion and its resulting air pollution and health impact, is taking place in major cities throughout China. However, the literature on the impact of the new subway line openings on particulate matter with a diameter less than 10 µm (PM10) at the city level is scarce. Employing the Propensity Score Matching–Difference-in-differences method, this paper examines the effect of the new subway line openings on air quality in terms of PM10 in China, using the daily PM10 concentration data from January 2014 to December 2017. Our finding shows that the short-term treatment effect on PM10 is more controversial. Furthermore, for different time windows, the result confirms an increase in PM10 pollution during the short term, while the subway line openings improve air quality in the longer term. In addition, we find that the treatment effect results in high PM10 pollution for cities with 1–2 million people, while it improves air quality for cities with over 2 million people. Moreover, for cities with varying levels of GDP, there is evidence of a reduction in PM10 after the subway line openings. Mechanism analysis supports the conclusion that the PM10 reduction originated from substituting the subway for driving.

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“…Wind speed was measured there at 6, 12, and 18 UTC. The comparison of the values recorded at both stations shows the impact of urban build-up on the significant decrease of that element which largely deteriorates aerosanitary conditions inside the city area (e.g., Yang et al 2020). Additionally, each day with PM measurements was characterized with a few elements.…”

Section: Methodsmentioning

confidence: 99%

Impact of wind speed and apartment ventilation on indoor concentrations of PM10 and PM2.5 in Kraków, Poland

Ścibor

Bokwa

Balcerzak

2020

Air Qual Atmos Health

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In the period 2013-2015, PM 2.5 and PM 10 outdoor and indoor concentrations were measured on 23 days in cold half-year periods, in Kraków, Poland. Air pollution is still a serious health hazard for the inhabitants as Kraków is located in a concave landform and smog episodes occur often in the city during the heating periods, due to poor natural ventilation and frequent air temperature inversions. The PM 10 and PM 2.5 concentrations were studied for very good and very poor weather conditions concerning air pollution. Each subgroup was further divided into cases when the apartments' windows were kept open or closed. Daily courses of PM 10 and PM 2.5 concentrations were very dynamic. Weather pattern, in particular wind speed and atmospheric stability, largely determined the concentrations of PM 10 in ambient air. The share of PM 2.5 in PM 10 indoor concentrations reached around 70% for both types of weather conditions. The share of indoor PM 10 and PM 2.5 mean concentrations in the outdoor values was higher during good than during poor weather conditions by about 10%.

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Air pollution dispersal in high density urban areas: Research on the triadic relation of wind, air pollution, and urban form

Cited by 175 publications

References 30 publications

Impacts of Urban Form on Thermal Environment Near the Surface Region at Pedestrian Height: A Case Study Based on High-Density Built-Up Areas of Nanjing City in China

Impacts of Urban Form on Thermal Environment Near the Surface Region at Pedestrian Height: A Case Study Based on High-Density Built-Up Areas of Nanjing City in China

Can the New Subway Line Openings Mitigate PM10 Concentration? Evidence from Chinese Cities Based on the PSM-DID Method

Impact of wind speed and apartment ventilation on indoor concentrations of PM10 and PM2.5 in Kraków, Poland

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