The odor hit Sonya Rivera when she walked out of the house Monday morning to tend to her garden on St. Croix. “It’s a foul, funky smell,” she said. Another resident said it stank like rotten eggs; yet another said it smelled like sewage.

But everyone agreed on the source: Limetree Bay Refining, on the southern shore of the island.

Environmental Protection Agency and U.S. Virgin Islands officials are investigating a second harmful mishap at the controversial refinery after it emitted noxious fumes that prompted some schools and a coronavirus vaccination site on the island to close Friday.

The release of sulfuric gases from the facility, which caused nausea and eye irritation in some residents and came shortly after the Limetree Bay refinery in February showered oil on a neighboring community, has raised fresh questions about the operation.

On Tuesday a spokesman for the EPA Region 2 office, which oversees the U.S. Virgin Islands, said the agency would “send experts and staff to the facility as soon as this week to conduct a joint investigation” of the plant with territory officials.

“It is EPA’s objective to ensure that the facility operates in compliance with all applicable legal requirements without jeopardizing public health and the environment by its operations,” said EPA spokesman John Senn in an email. “The incidents have been distressing and, in some cases, caused members of this already overburdened community to become ill.”

Limetree and territory officials gave differing accounts of what emanated from the plant. Jean-Pierre Oriol, U.S. Virgin Islands planning and natural resources commissioner, said in a statement Friday that the refinery had released hydrogen sulfide, which can cause serious health effects at high exposure levels during a short period. The company, however, said the hydrogen sulfide had been converted to sulfur dioxide before entering the atmosphere.

Oriol said that his office was “aware of a foul, gaseous smell permeating throughout the Frederiksted area for the past few days” and was looking into the matter. He urged vulnerable residents to stay indoors until the fumes had dissipated.

The Department of Planning and Natural Resources “is advising the public that persons with respiratory ailments such as allergies, lung disease and asthma should consider taking protective actions,” Oriol said. “Protective actions include staying indoors or relocating to areas less affected.”

The fumes also forced the island’s coronavirus vaccination center on the University of the Virgin Islands campus to close Friday. It reopened Monday.

The company confirmed in a statement that it had experienced an accident that began Thursday night and lasted until early Friday, “which created a strong odor detectable outside the facility. Limetree has corrected the problem and will continue to monitor any additional impact to the outside community.”

On Saturday, it clarified that a pressure relief valve was triggered, sending “an unusually high amount of sulfur-containing gases” into a flare, where they were burned before being released into the air.

“The executive management of Limetree Bay sincerely apologizes on behalf of the entire organization for the unpleasant odor that came from the refinery yesterday and for its impact on our neighbors and the community,” it added. “We are committed to investigating fully the reasons for this event in cooperation with local regulators, and to implement improvements to prevent it from happening again.”

High levels of sulfur dioxide can not only irritate the eyes, nose and throat but cause inflammation of the respiratory system. Over time, it can contribute to lung and heart disease.

“It makes you a little lightheaded,” said Rivera, adding that the odor was present all weekend, even after Limetree said the problem was resolved. “My neighbor says she feels funny. I have a slight headache. The weekend, we didn’t go out. You can’t enjoy the weather outside. You can’t enjoy the beach. I don’t think [the company is going] to be here long. It’s just one thing after another.”

The refinery, which restarted operations nearly three months ago after the plant had been shuttered for nearly a decade, is already under scrutiny for a Feb. 4 accident that sent a fine mist of oil over broad swaths of the island, settling on houses as far as three miles away. The oil settled on cars, gardens, rooftops and cisterns filled with rainwater that residents use for drinking, cooking and bathing.

Earlier this month, the EPA sent a lengthy information request to the company, instructing it to provide details on not only the February event, but also any other accidental air releases that have taken place since the fall, when the refinery began preparing to reopen.

The refinery, which is a critical source of jobs and tax revenue to the territory, has come under sharp criticism from some residents who argue it poses an environmental and public health threat. The plant’s previous owners reached a multimillion-dollar settlement with the EPA in 2011 after acknowledging that the operation had released at least 300,000 barrels of petrochemicals and polluted the island’s one aquifer.

At least three schools on St. Croix closed, according to an alert issued by the territory’s education department that said that “students and staff have reported nausea due to the smell, which was detected April 22.”

Garfield Connor, a carpenter who works around the island, called the odor “just a very awful stench. You can definitely smell it right now if you’re on the west side of the island. It smells like sewage — it’s exactly what it smells like.”

Connor lives in a two-bedroom home with his girlfriend and 2-year-old. Because of the tropical heat, they keep the windows open with several fans blowing. “Even with the fans, you can still smell it,” he said.

Territory officials must decide whether the refinery’s job creation and taxes are worth its litany of accidents and the impact on the health of residents, Connor said. “We don’t really need the plant,” he said. “We were doing just fine when it was shut down. … The amount of jobs they provide to me aren’t sufficient to have it. I don’t see that it’s doing anything great for us.”

Russell Pate, a lawyer on St. Croix who represents residents who sued the refinery’s previous owner, said in an email he has been “choking in the smell” even though he lives five miles from the plant.

“The gas smells like a combination of natural gas and hot road asphalt tar and causes headaches over time,” Pate said, adding that the effect was especially acute in poorer neighborhoods where residents lack air conditioning and keep their windows open to stay cool.

A month ago, the EPA revoked a permit that the Trump administration had awarded the company and that would have allowed it to expand operations, saying it wanted to assess what pollution controls were needed and to what extent it disproportionately harmed residents of color living closest to the refinery.

“I get up early to do my garden. It’s so much in your face it feels like you’re close to it,” Rivera said of the smell. “I feel for my husband because he works outside. It’s not a good thing. I’m thinking about our health. It can’t be good for us, the constant breathing of this.”