A federal appeals court ruled Friday that the Environmental Protection Agency must delay implementation of pending regulations aimed at limiting harmful power plant pollution that crosses state lines.

The ruling prevents EPA from implementing the cross-state air pollution rule — which would put new limits on sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions from power plant smokestacks in 27 Eastern states — on Jan. 1, as scheduled.

EPA said the power plant emissions travel across state lines, threatening the health of thousands of people.

A coalition of utilities and industry groups that oppose the regulations petitioned the court to halt their implementation, arguing they will harm the economy and threaten the reliability of the power grid.