https://arstechnica.com/tech-policy/2024/06/supreme-court-puts-epas-plan-to-limit-ozone-emissions-on-hold/

On Tuesday, a slim majority of the US Supreme Court issued an emergency ruling that places a stay on rules developed by the Environmental Protection Agency, meant to limit the spread of ozone-generating pollutants across state lines. Because it was handled on an emergency basis, the decision was made without any evidence gathered during lower court proceedings. As a result, the justices don't even agree on the nature of the regulations the EPA has proposed, leading to a blistering dissent from Justice Amy Coney Barrett, who was joined by the court's three liberal justices.

The rule at issue arose from the EPA's regular process of revisiting existing limits in light of changes in public health information and pollution-control technology. In this case, the focus was on ozone-producing chemicals; in 2015, the EPA chose to lower the limit on ozone from 75 to 70 parts per billion.