The Environmental Protection Agency building is shown in Washington. (Pablo Martinez Monsivais/AP)

Bill Wehrum, the Environmental Protection Agency’s top air policy official, continued to stay in close touch with employees at his former law firm after joining the Trump administration, according to documents released this week under the Freedom of Information Act.

The trove of emails between Wehrum and officials at Hunton & Williams — which changed its name to Hunton Andrews Kurth after a 2018 merger — shows the extent to which he communicated and socialized with his former associates even though many of them had clients with business before the EPA. The documents were released Monday as part of ongoing litigation by the Sierra Club, an advocacy group.

Wehrum, who worked as a partner at Hunton between stints at the EPA under Presidents George W. Bush and Donald Trump, represented a number of industry groups during his time as a corporate lawyer. Those included American Fuel & Petrochemical Manufacturers, Duke Energy and Exxon Mobil.

In the emails, Hunton lawyers invited him to social events and kibitzed about policy matters. A week after Wehrum had joined the EPA as assistant administrator for air and radiation, an administrator at the firm, Julia Zemnick Gill, forwarded him an invitation to a 50th anniversary party for the D.C. office. On June 13, 2018, Chuck Knauss — a partner with the firm who serves on the board of the National Park Trust — invited Wehrum to attend an event at the Newseum that night honoring Sen. Martin Heinrich (D-N.M.).

Officials at Hunton, a firm that represents several clients from the oil and gas, coal, utility and chemical industry and has pressed EPA to roll back several rules and policies adopted under the Obama administration, declined to comment Wednesday.

In an interview Wednesday, Wehrum said he socialized with friends from his past job without crossing any lines and did not respond to work-related requests if they were inappropriate.

“There’s a group of people I had lunch with every single day for the last 10 years, and they’re friends of mine,” he said. “What I understand is, I can still be friends with friends of mine, if I don’t do business with them.”

At times, Wehrum’s former associates asked him for updates on EPA rulemaking or for introductions to other political appointees at the agency. On Feb. 6, 2018, Hunton special counsel David Craig Landin sent him an email asking about when a “scoping document might be expected” outlining the agency’s plans for implementing the Toxic Substances Control Act and whether Wehrum could “schedule an informal introduction” to two top EPA officials overseeing the program.

A little more than five months later, after former EPA administrator Scott Pruitt had resigned amid a slew of ethics scandals, Landin sent Wehrum a sympathy note.

“So sorry about Scott Pruitt, which I know means that your group has been going way into overtime,” Landin wrote. “Have meetings with client [sic] Tuesday and traveling tomorrow, but if a catch-up on general matters to get a sense of things is doable, let me know.”

Anybody can email me,” Wehrum said, referring to his exchanges with Landin. “The question is what I do about it, and the answer is, nothing.”

At times, according to the documents, Wehrum even joked about how the utility industry he once represented was shifting to the left. After an official from Southern Company sent him a news release on April 19, 2018, with the subject line, Southern Company is “Planning for a Low-Carbon Future,” Wehrum forwarded it the following day to Hunton partner Bill Brownell.

“Well, things sure have changed …” Wehrum wrote his former colleague.

In an email, Sierra Club Legislative Director Melinda Pierce said the documents show that Wehrum was continuing to back the same industries he worked for while in private practice.

“Wehrum’s frequent liaising with his former colleagues shows it’s not clean air or the health and safety of American families that Wehrum holds dear, but the fossil fuel industry is still number one in his heart,” Pierce said.