Community/External Quality and Safety

Climate Vulnerability (Extreme Heat)

Exposure to extreme heat can cause heat exhaustion, heat cramps, heatstroke, and death, as well as exacerbate preexisting chronic conditions, such as various respiratory, cerebral, and cardiovascular diseases (CDC, 2020). These serious health consequences usually affect more vulnerable populations such as individuals with preexisting physical or mental health conditions, people with high occupational or recreational heat exposure, young children, and seniors (Uejio et al., 2016). The occurrence of extreme heat and its adverse effects will be exacerbated by the trend of global warming. In Boston, it is expected that heat-related deaths would triple in the next thirty years (Petkova et al., 2013).


By using the climate vulnerability dataset released by Metropolitan Area Planning Council (MAPC), we present geographical disparity in vulnerability to extreme heat among different neighborhoods and regions.


The top layer of the data maps represents a census tract’s relative vulnerability to extreme heat, compared to the others in the Metropolitan Area Planning Council (MAPC) region. For example, residents in Chelsea, Dorchester and Roxbury are likely to be more vulnerable to an extreme heat event than people living in other neighborhoods in the city of Boston. According to the MAPC, vulnerability is often characterized as integrating three dimensions – exposure, sensitivity, and adaptive capacity. The vulnerability index is the average value of indices from the three dimensions (please see below the maps for more information about each layer).

Quick facts from the data maps:

  • 3 of 101(2.9%) MAPC municipalities fall in an extremely high vulnerability region: Boston, Chelsea, and Lynn.

  • Among the 175 census tracts of Boston neighborhoods, 47 are highly vulnerable to extreme heat.

[1] Exposure: this layer represents to what extent a census tract is exposed to extreme heat events. It is measured by the average temperature increase by heat islands in that census tract taking into account the number of housing units. Land cover and land use play an important role in exposure to extreme heat events. For example, individuals living in areas covered by impervious surfaces (e.g. buildings and roads) experience more heat than individuals living in areas with open space such as parks, and less buildings. Impervious surfaces retain heat and take time to cool down, creating heat islands that are substantially warmer than areas with open space.


[2] Sensitivity: this layer represents the degree to which the census tract is affected by the exposure to heat. The sensitivity to heat depends on age and health status of the resident population, occupations that are exposed to heat events, and housing conditions.


[3] (Insufficiency in) Adaptive Capacity: adaptive capacity represents ability of a census tract to anticipate, cope with, and recover from the impact of heat events. The defining indicators include race and ethnicity of the resident population, housing demographics, mobility, and access to resources, social networks, and information (e.g. about heat protection measures). *Note: the legend illustrates the levels of insufficient adaptive capacity from extremely low to extremely high.


  • CDC. (2020, February 20).

  • MAPC. (2019). Climate Vulnerability Analysis. Climate Vulnerability Analysis. Retrieved September 3, 2020, from here

  • Petkova, E., Horton, R., Bader, D., & Kinney, P. (2013). Projected Heat-Related Mortality in the U.S. Urban Northeast. International Journal of Environmental Research and Public Health, 10, 6734–6747. 

  • Uejio, C. K., Tamerius, J. D., Vredenburg, J., Asaeda, G., Isaacs, D. A., Braun, J., Quinn, A., & Freese, J. P. (2016). Summer indoor heat exposure and respiratory and cardiovascular distress calls in New York City, NY, U.S. Indoor Air, 26(4), 594–604.