Cooler Heads - The deadliest environmental threat to city dwellers worldwide isn't earthquakes, tornadoes, flooding, or fire. It's heat.

The deadliest environmental threat to city dwellers worldwide isn't earthquakes, tornadoes, flooding, or fire. It's heat. In Phoenix, Arizona, where almost 400 people died from heat exposure last year-and where falling on the pavement can leave a third-degree burn-the question isn't whether this summer's temperatures will kill people, it's how many.

- By Camille Bromley- illustration by Johanna Goodman

In Phoenix, Arizona, where almost 400 people died from heat exposure last year-and where falling on the pavement can leave a third-degree burn-the question isn't whether this summer's temperatures will kill people, it's how many.

The answer hinges, in part, on a small team the city created in 2021 to deliver aid during heat emergencies: handing out supplies, opening relief centers, and even driving a bus to bring cool air to where it's most needed. The team is also trying to make Phoenix cooler over the long haul by finding space for shade trees-which is a major challenge in the city center. As the adage goes, the best time to plant a tree is 20 years ago.

So in the meantime, there's triage.

Here, one member of the city's Heat Response and Mitigation Office tells WIRED what it's like to go out on the streets day after day in temperatures that reach 110 degrees or higher.

When a tornado comes through, you can see houses are ruined. With heat the damage is not as visible. You see it in the numbers. Everyone's like "dry heat this" and "dry heat that", but it's dangerous.

I'm constantly trying to keep my body ready for those higher temperatures. I drink electrolytes 24/7, year round.