When Elle Wiernik bought her new home in 2020, she didn’t know about the abandoned gas well in the woods, some 1,000 feet from her house at the Lafayette Meadow development in South Fayette.

But she smelled it as soon as she moved in — and on and off for nearly two years, until the decades-old hazard was finally plugged under an emergency contract from the Pennsylvania Department of Environmental Protection.

What she still didn’t know until this week is that the well was leaking not just methane, the main component of natural gas, but substantial volumes of benzene, a known carcinogen.

It was the biggest emitter of benzene, along with other toxic air contaminants, in the findings of a recent study in the journal ACS Omega, in which researchers reported the discovery of harmful volatile organic compounds, or VOCs, leaking from 48 abandoned wells in Western Pennsylvania. The emissions from the South Fayette well were so pungent and irritating that researchers cautioned anyone taking air samples at the site to wear protective respiratory gear.

Scientists have long known from studies of active drill sites that oil and gas wells produce a wide range of hazardous air pollutants.

Yet until now, no independent researchers had systematically measured toxic air contaminants from any of the more than 3 million abandoned oil and gas wells scattered across the nation.

In the study, researchers with the nonprofit research and policy institute PSE Healthy Energy measured both the emission rates and the concentrations of harmful VOCs coming from abandoned wells in the heart of the nation’s largest gas field, the Marcellus Shale.

“Our study is the first to thoroughly identify that there is a benzene hazard associated with abandoned wells,” said the lead author, Seth Shonkoff, the executive editor of the research institute, PSE Healthy Energy.

Many were releasing benzene, a well-established cause of cancer, along with compounds that damage the nervous, immune and respiratory systems, the researchers reported. They found air concentrations as high as 250 parts per million—250,000 times the California safety threshold of 0.001 parts per million, which public health experts use as a gold standard because it tends to protect the most vulnerable populations, such as children.

The U.S. Environmental Protection Agency classifies benzene as a known human carcinogen for every route of exposure, whether inhaled, ingested or absorbed through the skin, and the World Health Organization has concluded that no safe level of exposure to benzene exists.

VOCs like those found at the abandoned wells are also well-established precursors of smog, or ground-level ozone. Exposure to ozone is linked to diverse health problems, including uncontrolled asthma requiring emergency room visits and hospitalization, and cardiovascular and respiratory disease leading to premature deaths.

While some of the abandoned wells investigated for the study are buried in remote areas, 93 percent are within 3,280 feet of buildings and homes, the team found. Nearly a quarter are just 328 feet from buildings and homes—less than the length of a football field.

Joan Casey, an environmental epidemiologist with the University of Washington’s School of Public Health who was not involved in the study, said the article’s findings were disappointing but not surprising.

“Most of our health studies to date have focused on residential proximity to active oil and gas wells and have completely ignored this subset of abandoned wells,” said Ms. Casey.

That means the public health community is missing “this whole other set of exposures” in evaluating the impact of oil and gas wells, she said.

“If what is found in this study is generalized to all of our abandoned wells, we definitely don't want people living near them.”

Often, the Only Option: Testing Wells on Public Lands

The fact that some abandoned wells are releasing a carcinogenic compound at very high levels raises serious concerns about air quality, groundwater quality and people who could be exposed to problems with both, Mr. Shonkoff said. And it adds to a larger body of research on what makes up natural gas as it travels through the oil and gas supply chain, from wells to the pipelines that supply homes and buildings.

“What we've found across all these studies, which has actually been quite surprising, is that all of this gas is not just methane,” he said. Almost every single sample of gas across the supply chain, including abandoned wells, contains cancer-causing benzene, his studies have found.

Industry research has already identified emissions of benzene and other gases from active oil and gas wells, said Kyle Ferrar, a public health expert with the nonprofit FracTracker Alliance.

Pennsylvania regulators believe that some 200,000 wells that have been abandoned since the first was drilled in the 1850s are missing from state databases. Some remain unaccounted for because they predate modern well-permitting and plugging requirements.

For others, historical records indicate that the wells existed but lack coordinates to show where they were, said Neil Shader, a spokesperson for the Pennsylvania Department of Environmental Protection.

“We can account, for sure, for about 27,000,” he said. “But the rest are lost to history, buried in dead leaves and dirt, paved over, et cetera.”

Staff members from the DEP helped Mr. Shonkoff’s researchers locate the 48 wells so they could collect and analyze gas. Because most were on public land, the team didn’t need permission to gain access to the sites.

The results demonstrate that the geology underlying the wells affects what comes out of them. When the researchers compared their Pennsylvania readings to spot samples taken in other oil and gas formations across the country, they saw that benzene concentrations varied considerably by location.

“This information should be taken into consideration as we think about which wells to prioritize plugging first, with the limited amount of resources we have to address this massive problem,” he said. That would mean identifying the abandoned wells with the highest emissions of harmful substances and then determining which are closest to communities and their drinking water sources.

In one case, the researchers discovered that an unplugged abandoned well sat as little as 33 feet from the rented home of a family that had no idea that the pipe in the backyard was an old gas well. The team did not detect benzene at the site but recorded daily methane emissions high enough to pose the risk of a fire and explosion.

Many residences and buildings in oil- and gas-producing regions across the country are built on top of abandoned wells, unbeknownst to the owner or builder, Mr. Shonkoff said.

A Trillion-Dollar Problem

Last year the Biden administration announced a $4.7 billion program to clean up abandoned wells under the 2021 Infrastructure Investment and Jobs Act. Mr. Shader of the Pennsylvania DEP said the agency had received $25 million so far in federal funds to plug abandoned wells and hoped to secure nearly $400 million in all.

But plugging thousands of abandoned wells in the state would likely cost billions.

Operators in Pennsylvania must post a bond of $2,500 to drill a new well (and up to $25,000 to cover all wells they drill). They forfeit the money to the state if they abandon the well without plugging it, Mr. Shader said. But state officials estimate that it costs an average of $33,000 to plug a well, and as much as $800,000 if the job requires clearing years of debris.

The Pennsylvania Independent Oil and Gas Association did not respond to requests for comment on the study.

Given that many of the wells sampled were emitting harmful gases, sometimes at very high rates, near homes, the study’s authors wrote, “further investigation is necessary to determine whether gas emissions pose an inhalation risk to people living, working, or congregating near abandoned wells.”

This story is published in partnership with Inside Climate News, a nonprofit, independent news organization that covers climate, energy and the environment.

The Post-Gazette’s Anya Litvak contributed.

First Published: June 8, 2023, 9:30 a.m.
Updated: June 8, 2023, 3:48 p.m.