People who live near active or dormant oil wells have poorer lung function than those whose homes are farther away, according to a study of two predominantly low-income Black and Latinx neighborhoods in South Los Angeles.

The researchers surveyed and tested nearly 1,000 people and found that residents living near an active drilling site were also more likely to report symptoms such as wheezing. The findings were published March 29 in the journal Environmental Research. 

"This helps provide epidemiological evidence about potential impacts of having oil-drilling operations in neighborhoods," said Jill Johnston, an assistant professor of preventive medicine at the Keck School of Medicine of the University of Southern California and first author of the study. "We need to think about how to better protect public health and how to address some of the existing health disparities, which may be exacerbated by the presence of these industrial operations inside communities."

There are approximately 40,000 oil fields globally with the potential to affect more than 600 million people nearby, Johnston and her colleagues wrote in the study. In the United States, an estimated 8.6 million people live within 1,600 meters from an active oil-extraction site, many of them in California, Texas, North Dakota and Alaska.

The nation's largest urban oil field is found in Los Angeles, with thousands of active oil and gas wells located near homes, schools and parks. About one-third of the 10 million residents of Los Angeles County live within a mile of an active drilling site, and some live as close as 60 feet. Multiple air pollutants have been linked to petroleum extraction, including carcinogens such as benzene, formaldehyde, sulfuric acid and particulate matter, which are known to cause breathing problems, dizziness, headaches and fatigue. 

"Because oil-drilling markets will fluctuate, we have some places in the city where they're actively extracting wells and other places where it's not fully closed or shut down, but they're in this stage of being idle or inactive, so they could start operating at any time," Johnston said. "So that remains a concern for the community, to have these idle oil wells there."

She and her team focused on the neighborhoods atop the Las Cienegas oil field, where about three-quarters of households live below 200% of the federal poverty line. After an increase in oil production in recent years, residents began to report foul odors and symptoms such as nosebleeds and headaches, similar to those described by people living near natural gas and hydraulic-fracturing sites in more rural areas.

"Most people who live in this neighborhood didn't know what was happening behind these cement walls, so they didn't realize they were living next to these oil-drilling operations," Johnston said. "That community lived experience is what prompted not only a larger awareness across Los Angeles about how these oil-drilling operations are happening in neighborhoods, but also a call for research to document what some of these health impacts could be."

Johnston's team visited two neighborhoods within the oil field. The North University Park neighborhood housed 21 idle wells, and the Jefferson Park neighborhood had an active site with 28 active wells. The researchers partnered with community health workers to recruit 961 residents between the ages of 9 and 85 living within 1 kilometer of oil wells. 

The participants answered a detailed survey about their health symptoms and blew into a device called a spirometer, which measures how much air people can exhale and how quickly they can do it. 

These markers, Johnston said, have been shown to be related to chronic respiratory disease or early mortality, "so they're kind of early indicators of potential health problems among people that have lower lung function."

She and her colleagues found that people living near the active drill site were two to three times more likely to report symptoms that included wheezing, sore throat, chest tightness, dizziness and eye or nose irritation than people living near the idle site. People living downwind or within 200 meters of either site generally had lower lung function than those who lived farther away.

"We saw this pattern in both neighborhoods, which suggests that some of these impacts of oil and drilling operations can lead to chronic effects," Johnston said. The magnitude of the reduction in lung function, she says, was on par with what researchers have reported in people who are regularly exposed to secondhand smoke or live near freeways.

The findings suggest that "there could be these respiratory health impacts that expand to other communities that are facing similar types of oil and gas development," Johnston said. 

However, she points out, the researchers weren't able to account for potential other reasons the participants might have been exposed to hazardous substances. For their next steps, they hope to follow up with participants over time and monitor levels of methane, which is a marker of oil extraction, in the communities to gather more detailed information about when and where people might be exposed to pollutants.

"There's a lot of community organizing happening and conversations both in the city of Los Angeles and in the state of California to think about public-health protections that could be a part of permitting of oil and gas facilities, as well as their operations," Johnston said. 

The Los Angeles City Council is considering an ordinance that would outlaw oil drilling within the city. Another important step is reducing the emissions from drilling sites.

"You see that some well sites are fully enclosed; they are operating inside a building in neighborhoods such as Beverly Hills," Johnston said. "But when you look at South Los Angeles, they're surrounded by a wall, but they're essentially operating in open air, which increases the potential for these toxins to transmit to nearby areas."

The study, "Respiratory health, pulmonary function and local engagement in urban communities near oil development," published March 29 in Environmental Research, was authored by Jill E. Johnston, Temuulen Enebish and Sandrah P. Eckel, University of Southern California; Sandy Navarro, L.A. Grit Media; and Bhavna Shamasunder, Occidental College.