Heat takes a disproportionate toll on low-income communities of color that often live in neighborhoods that have older, lower quality building stock, less tree cover, and fewer buildings with air conditioning.

Studies like Jesdale 2013 highlight the significant racial differences in the populations who are experiencing elevated heat risks. That study found that Black Americans are 52% more likely to live with elevated heat risks than White Americans. Many cities have undertaken heat vulnerability analyses of their neighborhoods, taking into account health conditions, social connectivity, prevalence of air conditioning, tree cover, and reflectivity. In almost all cases, the most vulnerable areas are also the least wealthy.

Comparisons of heat-related deaths by racial or ethnic groups show mixed results. Kalkstein and Davis (1989) found strong correlations between heat mortality and percent non-white only in southern U.S. cities. In Detroit, nonwhites had a higher risk of death on hot days (O’Neill et al. 2003; Schwartz 2005), and during the 1995 Chicago heat wave, non-Hispanic blacks had higher death rates than did non-Hispanic whites (Whitman et al. 1997). In a case–control study, blacks had a higher death rate than did whites; however, both had higher rates than did Hispanics (Basu 2009). Modification of the relationship between heat and mortality by race, however, has not been found in all studies (Braga et al. 2002). Differential mortality rates may be partially explained by differences in air conditioning (AC) prevalence in homes by race.  64% of the disparity in heat-related mortality between blacks and whites from four U.S. cities may be explained by the prevalence of central AC in homes (O’Neill et al. 2005).

Heat health and wealth are highly correlated. The graph below shows the annual heat-related emergency room visits per million compared against a neighborhood’s percentage of residents under the poverty line. The poorest neighborhoods interact with the emergency health system for heat ailments over two times more frequently than wealthy neighborhoods.

In addition to direct heat-related illnesses, heat exacerbates a wide variety of conditions like renal, cardiopulmonary, and respiratory diseases.

Heat stress and stroke are only the tip of the pyramid of heat health impacts. Heat puts significant additional stress on people already suffering from diseases of the heart, lungs, kidney or diabetes. On the positive side, new field research in Louisville finds that reduced heat and green barriers to roadways led to measurable improvements in the body chemistry of school children at a school that had just had the urban heat mitigation technologies deployed.

Heat is a potent but silent killer.  In 2015, Scientific American reported that 9 out of the 10 deadliest heat events in history have occurred since 2000 and have led to nearly 130,000 deaths.

Cooler temperatures make better conditions for picnics, exercise, and outdoor time with friends and family.

A study evaluating the exercise habits of 1.9 million Americans found that very hot weather led to a substantial decline in physical activity. (Obradovich 2017)