Summer can bring sweltering heat waves. And that’s not just unpleasant. It can cause heat stroke or make people’s heart or kidney problems worse.

“We talk about it a lot as a silent killer. You know, it’s not people directly dying from heat as often as indirect effects,” says health data analyst Jackson Voelkel.

Voelkel researched extreme heat while at Portland State University. He says urban residents face the hottest temperatures. Dark pavement and roofs absorb heat, so cities tend to get warmer than surrounding areas. But even within a city, temperatures can vary widely depending on tree cover, vegetation, and building types.

For example, Voelkel’s research shows that the hottest areas in Portland, Oregon, tend to be where low-income people of color live.

“It also lined up with education,” he says. “People with lower education also lived in hotter areas.”

He says other environmental disparities may get more attention because they’re more visible.

“If they built a coal-burning power plant next to your house, you’d be very aware of that,” he says.

But extreme heat is also a serious threat, and it’s growing as the climate warms. So he says vulnerable residents need to know the risks and have access to solutions.

Reporting credit: ChavoBart Digital Media.