The announcements came as Scott Pruitt, the administrator of the E.P.A., has been denying accusations by environmental advocates that he is weak on enforcement. A recent study by the Environmental Integrity Project, based on documents obtained under the Freedom of Information Act, found the Trump administration had collected 60 percent less in civil penalties from polluters through July 31 than the previous three administrations over a similar period.
But in a recent interview with Bloomberg, Mr. Pruitt vowed to crack down on polluters, saying, “They don’t know me.”
Jeffrey H. Wood, acting assistant attorney general for environment and natural resources, said that since January the environment division has imposed more than $1.7 billion worth of civil penalties and $2.9 billion in criminal fines.
Tuesday’s settlements resolve allegations that Exxon and PDC Energy violated the federal Clean Air Act by releasing harmful pollutants.
In the case of PDC, the company has agreed to spend about $18 million to upgrade systems. The Exxon settlement is expected to reduce releases of volatile organic compounds by more than 7,000 tons per year and reduce toxic air pollutants like benzene by more than 1,500 tons per year, Mr. Wood said. The settlement also requires the company to spend $1 million to plant trees in Baytown, Tex.
Exxon’s Baytown operation came under scrutiny during Hurricane Harvey this year for releasing toxic pollutants during the storm, which battered refineries and other chemical facilities along Houston’s coastline. In one case, a sinking tank roof at Exxon’s Baytown facility resulted in the release of hazardous gases — including volatile organic compounds and benzene — above permitted levels.
“These investments, which include flare monitoring equipment and flare gas recovery systems, will help improve flare efficiency at these chemical facilities, which are among the largest petrochemical complexes in the world,” Aaron Stryk, an Exxon spokesman said in a statement. “Exxon Mobil complies with environmental laws, regulations and permits.”