The danger of urban ‘heat islands’

Heat is sneaky. It worsens pre-existing conditions, such as heart and lung disease, kidney problems, diabetes and asthma, more often than it kills directly. “People end up going to the hospital because heat affects their health, makes their asthma worse or something worse,” says David Eisenman, a professor of medicine and public health at UCLA. “But it’s not technically coded as that in the records. It’s coded as ‘worsening asthma.’ So we really undercount the number of cases where heat is a factor.”

“There’s been this assumption that we can all cool off somehow. And in some ways that might have been true 100 years ago,” Eisenman says. “We don’t have access to the natural cooling environment like we did before.” 

The landscape’s cooling elements disappeared long before Edwin Díaz and his mother arrived in the valley. Their Pacoima neighborhood derives its name from the Native Tongva word for a place of running water. (These days, the now concrete-locked Pacoima Wash, a flood-control channel, is often dry.) After World War II, the neighborhood boomed when developers marketed boxy homes to African-Americans shut out of other parts of the valley by racial covenants.

Today, Pacoima is overwhelmingly Latino. And its single-family homes have produced a complex urban density, says Max Podemski, planning director for the community advocacy group Pacoima Beautiful. Lawns have given way to paved-over yards. Second-dwelling units, divisions within ranch homes, and modified garages can house several families together.

To understand more about how heat moves through Pacoima housing, last summer I built small electronic sensors to record dozens of heat and humidity measurements an hour, during parts of August, September and October: the hottest months in Los Angeles. One sensor went in Edwin’s bedroom.

In early afternoon, that sensor recorded temperatures equal to those recorded outside, at the weather station at Van Nuys Airport. Evening temperatures in Edwin’s room were up to 9 degrees higher than outside.

But the ways buildings respond to climate vary. In Herrera’s apartment, a lack of insulation, common in older California houses, may be the key factor. In the evening, she says, “We can feel the warmth in the walls.”

The blanket of heat smothering LA hasn’t escaped City Hall’s notice. Mayor Eric Garcetti has set an ambitious goal to lower the city’s overall temperature 3 degrees in 20 years. LA’s Office of Sustainability is studying where and how to deploy landscape-level cooling strategies, such as planting trees and developing cooler pavements. But it will take years to even know whether the goal is achievable.

In the meantime, renters like Herrera’s family battle excessive heat mostly alone. According to the Census Bureau’s National Housing Survey, half as many rental properties in Los Angeles have central air as do owner-occupied units. Coping costs money. In summer, Herrera’s power bill can be as high as $200 a month.

As temperatures rise in the Southwest, so do the stakes for city dwellers. In Phoenix, the Maricopa County Health Department has closely tracked heat-related death for more than a decade, producing an exhaustive report each year breaking down cases by age, ethnicity, economic background and other risk factors. 

Arizona State University researchers are working with Maricopa and Los Angeles counties to better understand how heat causes sickness and death, and how to counteract it.

“Many of us believe that no one should die prematurely because of heat, and there are significant public costs associated with heat just in the health-care sector alone,” says David Hondula, an ASU climatologist who studies heat impacts. Heat-associated deaths are climbing in Phoenix, but the reasons remain unclear. “If we can’t even answer that question, figuring out the best strategy to keep Phoenicians safe, or residents of Los Angeles safe, in a future that is expected to be warmer than it is today, would seem almost impossible,” Hondula says.

Paying for this has meant skimping elsewhere: fewer outings, no new clothes. Herrera worries that tight finances will force them to turn the air conditioners off. Still, “all the changes we’ve made are helping us,” she says. “It’s better to invest a bit more because health comes first.”

[This story was originally published by High Country News.]

[Photo by Doc Searls via Flickr.]