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Park inequality in Southern California creates health risks, especially during the heat

April 12, 2026

Rod McThompson is only weeks away from earning a master’s degree in engineering, but he says that doesn’t mean he knows anything about how sensors mounted on the International Space Station, orbiting 250 or so miles above the earth, can measure the surface temperatures of strips of land not much bigger than the parcel under his two-bedroom home in South Gate.

Or about how that technology produced the data used in a new report, conducted by researchers from UC Irvine and Chapman University, that shows how parks in South Los Angeles are hotter — by about 15 degrees, on average — than the parks in West Los Angeles.

What McThompson does know is this: If he wants to take his 3-year-old daughter, Jada, to the park closest to their house, they have to drive. And once they get to the park, he needs to make sure Jada is wearing a long-sleeve top and what the toddler describes as, “My tiny, tiny, tiny yoga pants.”

“The slides get hot. The swings, the monkey bars, all that (stuff); it’s all hot,” McThompson said during a recent hot spring day at Circle Park in South Gate. “If she got burned, she’d be upset. And of course I’d be upset. And my wife would be…”

He laughed.

“Let’s just say it wouldn’t be good for me, either.”

The McThompsons make the best of a situation that’s common and complex: park inequality.

Some elements of the problem aren’t new. Cities throughout Southern California — sometimes even multicity regions — can be divided into unofficial zones: park haves and park have-nots.

Residents and city planners intuitively understand this, and recent data bears it out.

In Santa Ana, only about 3% of the city’s land is devoted to parks, one of the lowest parkland ratios of any big city in the nation. In Irvine, the parkland ratio is about 27%, according to the 2025 City Park Facts report by the Trust for Public Land, a nonprofit aimed at developing and preserving urban open space.

Other data, from the cities themselves, show other park discrepancies throughout the region.

Baldwin Park has roughly a quarter acre of parkland for every 1,000 residents while in Whittier, just across the freeway, the ratio is about 3.4 acres per 1,000 residents. (Both cities fall well under the national standard, which is 10 acres of park per 1,000 people.) Manhattan Beach, a city of about 33,400, has 81 acres of park. Nearby, Lawndale has about 30,160 people and roughly 30 acres of park. In Pasadena, officials approved spending $25.8 million on parks in 2024. In South Pasadena, the city plans to spend $8.8 million on parks over the next five years. And so on.

This slice of the park problem — the simple existence or non-existence of parks in a given community, often described as “park accessibility” — has been known and debated long enough that there’s already been a concerted public effort to fix it.

In 2016, Los Angeles County voters approved a spending plan (Measure A) that allocated more than $1 billion to city parks. In 2018, California voters approved the “Parks, Environment, and Water Bond Act” (Proposition 68), which allocated $4.1 billion statewide to build more urban parks. About 20% of that money was aimed at communities deemed historically disadvantaged, park-wise, including the McThompsons’ hometown, South Gate.

Both programs have created some parks and open space that are helping to alleviate, if not fix, the basic issue of park access.

But the report released this month from UCI and Chapman, the one using satellites and heat sensors and lots of public input, reveals a different slice of the park problem.

Not all parks, it turns out, are created equal.

Public threat

The parks used by the McThompsons and others in South Los Angeles include a lot of heat-trapping materials — artificial turf, concrete, hard plastics, rubber mats. Also, because they’re often newer or carved out of land in or near industrial zones, the parks in South Los Angeles don’t have as many mature, shade-generating trees as the parks in West Los Angeles.

The upshot is that some parks offer residents a sanctuary they can use to dodge extreme heat, which is the biggest factor in climate-related illness and injury. Others don’t.

During summer days from 2021 through 2024, the surface temperature in dozens of parks and open spaces and school yards in Los Angeles averaged about 105.8 degrees Fahrenheit, or roughly 14 degrees hotter than similar temperatures at parks in West Los Angeles, which averaged 91.6, according to the new report.

Those differences aren’t trivia. The report found that roughly 1 in 3 parks in South Los Angeles routinely got hot enough to exceed the human pain threshold which, on land, is about 111 degrees. None of the parks in West Los Angeles hit that mark.

A potential factor, of course, is the ocean breeze. It blows through much of West Los Angeles; it doesn’t in South Los Angeles.

It also doesn’t matter.

“Think of it like when you’re walking on the beach, in, say, Santa Monica, and you’re barefoot on the sand. The wind and the ocean are making you cool, but your feet might be burning. It doesn’t matter what the breeze is doing; that sand is hot as hell,” said Joshua Fisher, a climate scientist and associate professor at Chapman University who helped lead the report.

“At the parks in South L.A., it doesn’t matter what the breeze is doing, that place is soaking up energy,” he added.

“If you’re a kid going down a slide, you might have the breeze to cool off your face, but your skin is going to burn.”

Prior to taking a job at Chapman about five years ago, Fisher spent a dozen years working at NASA’s Jet Propulsion Laboratory near Pasadena. He helped create and run the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (a.k.a. ECOSTRESS), which uses devices mounted on the International Space Station to track the daily surface temperatures of small patches of earth, at different times and days. Information as diverse as plant hydration and urban hot zones — the temperature spikes that happen in places like Phoenix, Las Vegas and Inglewood — are tracked and stored for public use via the ECOSTRESS system. And everybody from climatologists and firefighters to farmers and urban planners use that data to help make decisions.

The information about the parks in South Los Angeles, he noted, dovetails with other ECOSTRESS data about where heat tends to pose the most danger to the most people.

“The places where parks are super hot also are places where residents don’t have as much access to places where they can get relief from the heat. And it’s happening at a time when heat is becoming an increasingly common threat,” Fisher said.

“So it’s bigger than parks.”

Jason Douglas, UC Irvine associate professor and vice chair of health, society and behavior, conducts fieldwork measuring the surface temperatures of park equipment. (Photo by William Pomeroy)

Useful data

It’s also bigger than wonky talk about climate science and global warming.

The parks report was launched, in part, by what Fisher and a UC Irvine public health expert, Jason Douglas, heard during meetings with people who live near the parks in South Los Angeles. Douglas, along with others connected with the study, hopes the findings can be used in ways that go beyond academic research.

“This whole project really began after we went into the community and heard about these issues from the people who experience them,” said Douglas, an associate professor and vice chair at UCI’s Joe C. Wen School of Population & Public Health who specializes in working with historically marginalized communities to investigate public health issues.

“We eventually worked with more than 100 residents to map, specifically, where the problems were,” he added.

“Our philosophy was that all this NASA tech is amazing, but it can’t tell us how residents experience these places, and what the ramifications of climate change — extreme heat, in this case — are in their lives.”

Chapman University student Ashley Agatep is the lead author of a study that found Los Angeles parks in lower socioeconomic areas are 15 degrees hotter because of fewer trees and available shade. She is pictured at the university in Orange on Wednesday, April 8, 2026. (Photo by Mindy Schauer, Orange County Register/SCNG)

The paper’s lead author — Ashley Agatep, a 20-year-old junior at Chapman — agreed. She said she first got interested in using the ECOSTRESS mapping data to study parks in disadvantaged communities three years ago, when she heard about the idea from a graduating senior who didn’t have time to finish the project. After that, she said, she became more motivated by what she heard from people who use the parks.

“I was recording a lot of the testimonies from residents, and they were talking about what it was like for their kids to go to the park. One kid, the bottom pieces of his soccer cleats had melted,” Agatep said.

Now, she added, she’s excited about the idea that the report might be used by some residents to push city and county officials for better parks.

“This paper shows the role that science can fill for communities,” she said. “It isn’t getting lost in Google Scholar; it’s being used to make a difference.”

Agatep added that she plans to pursue a doctorate, probably in environmental science.

“I’ve fallen in love with research,” she said. “I just want to make sure my science serves my community.”

Park inequality in Southern California creates health risks, especially during the heat Orange County Register

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Park inequality in Southern California creates health risks, especially during the heat

Public threat

Useful data

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