The EPA under the Trump era is weighing a rollback of the regional haze rule, which since 1999 has driven states to cut emissions and improve visibility in more than 150 protected parks and wilderness areas.

In early 2025, EPA Administrator Lee Zeldin signaled plans to roll back 31 landmark environmental rules, including regional haze, to ease regulatory pressure on fossil fuels and invite public comment on softening the rule.

The regional haze rule requires decade-long state plans to reduce sulfur and smog emissions, significantly improving visibility in national parks and other protected areas.

Environmentalists warn the policy could let polluting plants stay online if visibility targets are met through retirements or fuel switching, undermining the rule’s intent.

Advocates caution that the rule could let states meet benchmarks without real reductions, effectively offsetting pollution rather than cutting it.

Public comment and litigation continue as of March 2026, with the EPA’s proposed softening of the rule under challenge.

Officials argue the agency must follow the law and ensure reliable energy, while critics warn the approach could erode two decades of regional haze progress.

The EPA says it cannot approve plans that fail to meet regulatory requirements, framing the shift as protecting grid reliability even as critics call it a rollback of air-quality protections.

Critics view Biden-era signals of stricter enforcement as being replaced by a backdoor delay or avoidance of stricter pollution reductions under the current policy.

Conservation groups sue over the policy, arguing it weakens protections and risks deteriorating park air quality by allowing facilities to stay online.

In Colorado and Hawaii, the EPA has rejected or signaled rejection of plant-closure plans tied to haze compliance, arguing grid reliability and affordable energy must be prioritized.

The agency contends that maintaining reliable energy supplies is a top priority, with plant closures weighed against energy security and demand.