A pair of studies released this week show heat exposure and pollution are disproportionately harming people of color and low-income communities. In all but six of the largest 175 U.S. cities, people of color experienced more exposures to heat than white residents, a study published in Nature Communications found. The term ‘heat island’ describes how concrete and asphalt in cities soaks up more heat, making cities hotter than the rural areas around them. The legacy of racist redlining policies, including the dearth of greenspace that worsens heat islands, exacerbates extreme heat in neighborhoods predominantly populated by people of color. Those researchers found heat island effects increased temperature in white neighborhoods by 2.6°F (1.47°C), less than half the 5.6°F (3.12°C) heat exposure increase experienced by Black communities.

“We thought [the heat exposure disparity] would be explained by income,” T.C. Chakraborty, the study’s co-author and a PhD candidate at Yale University, told the Washington Post. “But it was not.”

However, the second study, published in the Proceedings of the National Academy of Sciences, which focused on income and employment disparities, found the lower a ZIP code’s median income, the higher chances were its residents would be hospitalized for unscheduled respiratory issues resulting from heat and ozone spikes. Extreme heat and heat waves are some of the clearest impacts of climate change, kill as many as 5,600 people living in the U.S. every year, and are often worst in historically redlined neighborhoods. (Both: Washington Post $; Nature: AP; The Verge; Climate Signals background: Extreme heat and heat waves)