PROGRESS IN GEOGRAPHY ›› 2019, Vol. 38 ›› Issue (2): 296-304.doi: 10.18306/dlkxjz.2019.02.012

• Articles • Previous Articles    

Health effects of built environment based on a comparison of walkability and air pollution:A case study of Nanjing City

Xi CHEN(), Jianxi FENG*()   

  1. School of Architecture and Urban Planning, Nanjing University, Nanjing 210093, China
  • Received:2018-05-16 Revised:2018-12-27 Online:2019-02-28 Published:2019-02-28
  • Contact: Jianxi FENG;\customXml\item1.xml
  • Supported by:
    National Natural Science Foundation of China, No. 41871135;Fundamental Research Funds for the Central Universities, No. 090214380017.


Haze problem is becoming increasingly more serious in China. Improving walkability of cities to increase outdoor physical activities of urban residents may also increase their exposure to air pollution, and the health effect is not necessarily positive. In view of this paradox, by taking Nanjing City as an example, this study measured walkability and simulated air pollutant concentration based on a land use regression model and spatial interpolation. It then compared these to evaluate the health effects of the built environment. The calculation of the walkability score includes three steps: 1) Assign weights and distance attenuation of the concerned service facilities, based on which the basic walkability score of the point of interest (POI) is obtained. 2) Obtain the single-point walkability score of the POI, considering the impact of the walking environment. 3) Obtain walkability score by spatial interpolation. It was found that the walking index of the main urban area of Nanjing City showed a multi-center axial attenuation pattern. PM2.5 and O3 were selected as representative air pollutants for concentration simulation for their significant hazard. The concentration of PM2.5 was mainly simulated by establishing a regression model with relevant geographic variables, and the O3 concentration was simulated by spatial interpolation because it showed different characteristics in space. The result indicates that there is a large area of high walkability and high pollutant exposure. These areas are mainly distributed in the urban center. In such areas, it is risky to emphasize the improvement of walking activities through modifying the built environment to promote health. The area of low walkability and low pollutant exposure is mainly distributed in the suburbs, and it is difficult to directly assess the health effects of such areas. Health-promoting area of high walkability and low PM2.5 concentration is mainly distributed around the city's large green areas. Areas of high walkability and low O3 concentration are distributed in the second circle of the city center but not inside the center. Therefore, the surrounding area of green space that is close to the city center but not at the center is more likely to become space of high walkability and low pollutant exposure, which has positive health effects. On the other hand, the semi-urbanized areas at the junction of urban and rural areas tend to become space of low walkability and high pollutant exposure because industrial expansion does not match the lagging service provision. Such areas have negative health effects. The results can provide a reference for the accurate formulation of land use policies for healthy cities.

Key words: walkability, healthy city, PM2.5, O3, Nanjing City