SCIENCE SPOTLIGHT

The “heat island effect” disproportionately impacts communities of color.

As temperatures are increasing across the globe, certain areas are heating up faster than others. Concrete and asphalt surfaces that make up city centers bake in the sun and re-emit heat more than natural landscapes such as forests and wetlands, preventing urbanized areas from cooling off, even at night. As a result, urban areas become heat islands, anywhere from 1 to 7 degrees fahrenheit hotter than surrounding rural areas. 

The heat island effect contributes to a range of health concerns, including heat-related mortality which accounts for up to 1,500 deaths each year. Other consequences include heat strokes, dehydration, loss of labor, and decreased learning [1]. So, who is suffering the most from these consequences and overwhelming heat? 

Researchers from the University of North Carolina, Arizona State University and Yale mapped high-resolution satellite-based temperature data to demographic information from the US census across the 175 largest urban areas in the continental US. They found that the average person of color lives in a census tract with higher summer daytime surface urban heat island (SUHI) intensity than non-Hispanic whites in all but 6 of the 175 areas. 

In addition to experiencing disproportionate amounts of heat, people of color under the age of 5 or over the age of 65, the most vulnerable age groups to health-related consequences, are exposed to the same or greater level of heat.

Interestingly, they found the average person of color faces a higher summer daytime SUHI intensity than the average person living below poverty. This finding suggests that this inequality may not be explained by income alone, but perhaps fueled by historic redlining and inequal distribution of and access to resources based on race.

Redlining is the practice of systematically withholding services and resources from residents in specific neighborhoods based on race or ethnicity. It not only limits residents from living in places with more green spaces and tree cover, but designs systems that divide communities in ways that impact health and safety. This practice was common through the sixties (and continued beyond). Repercussions of redlining—like entrenched neighborhood racial segregation and economic disparities—are still felt in many U.S. cities today [2].

Some experts argue that creating more green spaces and planting more trees in redlined communities might actually cause an increase in home value, displacing individuals that the effort is meant to serve. Egede at al., state that the only sustainable path forward is one that simultaneously targets housing, education, healthcare, economic empowerment, the built environment, and access to healthy foods [3].