"If it becomes clear that there is a very strong lawsuit here, then it's going to affect your bidding," said Hughes, who is also the faculty director of the University of Pennsylvania's Kleinman Center for Energy Policy.

Carlyle and Credit Suisse Asset Management didn't respond to requests for comment on the refinery's benzene emissions or how they could affect the sale. Bardin Hill declined to comment and Energy Transfer Operating LP directed questions to PES, which also didn't respond to inquiries.

James Garrow, a spokesman for Philadelphia's Department of Public Health, said in a statement that "it is a well-known fact that refineries emit benzene during operation." He said that a city-run air monitor a half mile from where the refinery's highest benzene emissions were recorded didn't record excessive benzene emissions after the disaster and that any "responsible bidder" would seek out such information.

Reeves, the community organizer, was critical of the city's outreach efforts around the refinery sale.

"The same people, the same companies that allowed the stuff to happen are trying to decide what happens in the future," he said.

"Where are the people who still live here, who can't afford to leave?" he asked. "We're still getting kicked to the back."

Americans at risk

PES and most other U.S. refineries began monitoring benzene emissions on Jan. 30, 2018, to comply with a 2015 EPA rule that tightened emission standards for refineries.

In proposing the regulation, EPA argued that benzene — a naturally occurring component of crude oil and still a key ingredient in gasoline — is mainly released by leaking equipment. It's a good "indicator of other air toxics emitted from fugitive sources," the agency said.

When the rule took effect, PES was planning to go public and warned potential investors that the "fenceline monitoring requirement may lead to corrective action measures, including the installation of additional pollution controls, even if the refinery is otherwise in compliance with its air emissions permits."

The benzene monitoring requirement forced PES and other refinery operators to place air monitoring tubes around the borders of their refineries and then measure and analyze the amount of the carcinogenic gas that those monitors detected every two weeks. For refineries whose average annual emission topped the action level of 9 micrograms of benzene per cubic meter of air, the regulation required operators to determine the cause of the refinery's excess emissions and create a plan to reduce them.

"We project that no refinery should exceed that fenceline benzene concentration action level if in full compliance" with the stricter emissions standards, the rule said.

In weeks before and after the 2019 fire, some of the monitors along the fenceline repeatedly hit 190 micrograms per cubic meter. The emissions levels, however, could have been even higher since PES noted that the reading "exceeds instrument calibration range."

A sign advertising new townhouses built less than 1,000 feet from the Philadelphia Energy Solutions refinery site. Lisa Riordan Seville / NBC News

"Oh my god," said Bob Sonawane, a toxicologist who worked in EPA's Office of Research and Development for more than three decades. "The numbers that you're saying are very, very high, like some things happening in China, India and many other places."

In a corrective action plan required by the refinery rule, PES blamed many of its high benzene readings on a different company's petroleum terminal across the Schuylkill River as well as its own "benzene tanks and benzene unloading operations" that it argued are "nonrefinery operations and therefore not sources to be controlled." The refinery operator also promised to conduct additional sampling and inspections and work with the neighboring facility.

Garrow, the health department spokesman, said the city didn't receive the PES document until three days after the June 21 refinery disaster. But even then, city officials did not tell the public. At a press conference on June 25 about the refinery fire, Mayor Kenney told reporters "there are no findings that would suggest a threat to public health."

Eric Schaeffer, executive director of the Environmental Integrity Project and former head of EPA's enforcement office, cast doubt on the refinery’s attempt to explain away its high benzene readings.

"The monitoring they report is supposed to screen out background levels, including what comes from upwind sources," he said.

The plan also doesn't appear to be working. As of Sept. 25, 2019 — the last biweekly period EPA has posted online and more than two months after PES stopped producing fuel — the refinery's average annual emission level was 49 micrograms per cubic meter. That's higher than any other refinery that reported data to EPA and over five times the benzene action level.

Yet Sonawane, the toxicologist, said even the federal action level is "not protective of public health."

A hazard summary he worked on while at EPA warned that anyone exposed to air with more than 0.45 micrograms per cubic meter of benzene over their lifetime would have a greater than one in 1 million chance of developing cancer "as a direct result of continuously breathing air containing this chemical." That risk increases to more than 10 in 1 million at the level set by the federal refinery rule.

In Grays Ferry, that means residents, over a lifetime of exposure, may have been breathing air of a quality that the EPA estimates could be linked to an incidence of cancer of more than 100 adults out of a population of 1 million.

Asiya Reeves, 2, at her grandparents home in Grays Ferry. Lisa Riordan Seville / NBC News

Children in the neighborhood could be at even greater risk of developing certain cancers, Sonawane estimated, citing research published after 2003, when EPA last reviewed the health dangers posed by benzene.

For example, a 2015 analysis in the American Journal of Epidemiology found "children might be affected at lower benzene levels than adults."

Silent regulators

Public health advocates are critical of Philadelphia and EPA for staying mostly silent about the benzene levels in South Philadelphia and around the country.

"That makes no sense," said Schaeffer, with the Environmental Integrity Project. "It's bad government and bad corporate management."

Schaeffer criticized Mayor Kenney for failing to tell residents about the benzene problem and for not talking about the company's response, as the powerful investors who own the refinery try to sell it off.

Schaeffer was also critical of his former agency. While city officials may have incentives to keep quiet because of the impending sale, Schaeffer said that the "EPA shouldn't have quite the same constraints."

"That's why you have feds overseeing all these state and local programs," he said. "So they should be on the hook, too."

Public health and the environment are a top concern for EPA, the agency said in an email, and it has worked to reduce emissions from all types of facilities, including refineries. When it comes to informing the public, EPA said it often lets local partners take the lead.

Asked about the agency’s response to the PES plan to reduce benzene emissions, the agency said that it "does not comment on ongoing potential enforcement activities unless and until we take a public action."

For his part, Reeves expects little to change for the residents of Grays Ferry and other fenceline neighborhoods.

"The [bankruptcy] judge right now is making decisions without the input of the community," Reeves said while his grandchildren and a group of boys he mentors played on the street outside his home. He added that refinery workers had "told us to move."

But moving, he said, is not an option for many people in his neighborhood.