The Environmental Protection Agency and the National Highway Traffic Safety Administration are expected to propose loosening fuel efficiency standards next week, E&E News reports.

The EPA announced in early April that it planned to "revise" Obama-era emissions standards for cars and light trucks. This move will bring up questions about the waiver that currently allows California to set its own, stricter standards. As Pacific Standard reported:

No other state can ask for a waiver, but they can all adopt California's stricter rule, and at least 15 states have done so, including Pennsylvania, Georgia, and the New York metropolitan area. In effect, the California standards now apply to more than 40 percent of the population in the U.S.

California will likely take legal action to protect the waiver.

Transportation is currently the source of more than a quarter of emissions in the United States, and environmental groups are concerned that loosening clean car standards will lead to even more pollution.