The Biden administration has tightened standards for polluters that were rolled back under Trump — but it has not fully restored them to their pre-Trump levels.

The contested policies affect plants that were once considered “large” emitters of hazardous pollutants but have since taken steps to reduce their emissions.

Before the Trump administration, facilities that were once considered “major” sources of pollution were required to meet strict pollution requirements even if they reduced emissions, a policy known as “once in, always in.”

But in 2020, the Trump administration allowed polluters that had cut emissions to reclassify as smaller “area” polluters and comply with less stringent pollution control and reporting requirements.

The Biden administration’s actions restored pre-Trump requirements for facilities that are significant sources of seven types of harmful and persistent pollutants.

Removes contaminants such as mercury, a neurotoxin, as well as carcinogenic PCBs and dioxins.

But it leaves the Trump-era flexibility for other types of facilities.

Environmental and health advocates called the Biden administration’s actions a positive step, but many also called for a return to pre-Trump regulations.

“Overall, we think this is a really important step that will undo some of the damage that was done by the previous administration,” said Noha Haggag, senior staff attorney at the Environmental Defense Fund.

“While this is an important step, we would like to see the EPA ultimately take more action,” Haggag added.

Environmental Protection Agency (EPA) Administrator Michael Regan signed the final version of the rule on Friday, and it was posted on the agency’s website without much fanfare on Wednesday.

Asked for comment, an EPA spokesperson told The Hill that the rule “will ensure that sources of the top seven hazardous air pollutants continue to meet major source emission standards even if the source is reclassified as an area source.”

The Trump administration, in rolling back these protections, argued that it was encouraging polluting companies to invest in better emission control technologies and ending regulations that discouraged such investment.

Environmentalists disagree, saying the actions will likely lead to more pollution.

“Without a once-for-all policy, a large source could reduce emissions below the threshold and then legally increase emissions just below the threshold, or even exceed it, without being subject to rigorous monitoring requirements,” Haggag said on Wednesday.

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