Extreme Heat and Air Rule Delays Exacerbate Deadly Exposures

Extreme heat fueled by climate change is boiling swaths of the US, worsening exposure to toxic air pollution while key emissions regulations remain tied up in legal battles.

Temperatures continue to reach record-breaking levels in what scientists say was the hottest July in recent memory. The stifling heat also plays a big role in worsening air pollution nationwide, especially ozone, which relies on heat to proliferate.

“It is a perfect storm in that way,” according to John Balbus, acting director of the Office of Climate Change and Health Equity for the Department of Health and Human Services.

Rules to mitigate ozone pollution in summer months are baked into National Ambient Air Quality Standards, but the Biden administration’s efforts to tighten those standards are wrapped up in litigation brought by a coalition of states and industries that claim the agency exceeded its authority.

This summer’s heat wave and pollution nexus is a “deadly mix,” according to Marvin Brown, senior attorney at Earthjustice. “It is extremely concerning that these rules are delayed.”

Challengers have successfully frozen the so-called good neighbor ozone rule within their borders, but delays in this and other air pollution rulemaking leaves people more vulnerable to illness during heat waves like this one, according to advocates.

The updated good neighbor rule—which governs ozone pollution that travels across state borders—is set to take effect on Aug. 4, but Arkansas, Kentucky, Louisiana, Mississippi, Missouri, and Texas won’t be included in the implementation until courts decide their lawsuits. On top of that, additional air pollution regulations for ozone and particulate matter remain in early or proposal stages.

“More than one in three Americans are living in areas with unhealthy levels of ozone, and that bar of what’s unhealthy is already too generous,” Natural Resources Defense Council senior scientist Vijay Limaye told Bloomberg Law.

“I’m really alarmed as a health expert,” Limaye said.

Heat and Pollution

There is a deadly “synergy” between extreme heat and air pollution especially for vulnerable urban populations around transport hubs or industrial facilities, according to Balbus, who outlined heat-health risks on a call with reporters on Tuesday.

The toxic mix can spur short-term consequences including heat stroke or pulmonary distress, but also exacerbates deadly preexisting conditions such as cardiovascular disease. Studies show that a short-term combination of pollution and high temperatures raises mortality rates, especially for marginalized communities.

Exposure to air pollution particles is a “toxic force” inside the circulatory system, “that’s why air pollution is a trigger for heart attacks, because it inflames the inside of blood vessels and causes damage,” Balbus said.

Heat waves can also create harmful ozone pollution, causing a buildup of pollution as particles under heat domes accumulate and stagnate. Wildfire smoke, which has sullied the air across the US over the last few summers, is also part of this cycle. Extreme heat creates ideal conditions for fires to spark and subsequent smoke pollution to worsen.

Ozone is created when certain volatile organic compounds bake with other particles under heat, which is why the good neighbor rule and other ozone-specific pollution limits measure and mitigate emissions during the summer months.

Good Neighbor Woes

But a deluge of court challenges from Republican-led states against tighter wandering ozone standards will hold up the rules in certain states—for this summer’s ozone season, and perhaps into the next.

“Current legal challenges are delaying EPA from fully implementing the interstate programs to support states’ meeting the 2015 standard,” Harvard Law School Environmental and Energy Law Program staff attorney Hannah Dobie said in an email. “For reference, litigation to implement the interstate transport rules for 2008 ozone NAAQS just concluded in 2023.”

Rulemaking under National Ambient Air Quality Standards usually falls under legal scrutiny once finalized, a factor that can worsen delays in reviews of pollution levels, which are supposed to occur regularly under the Clean Air Act.

Court watchers say this round of litigation against cross-border ozone standards is more unusual because challenges are springing up across regional appellate benches and not just at the U.S. Court of Appeals for the District of Columbia Circuit. “Upwind” states regulated by EPA’s good neighbor plan are required to reduce their ozone-forming emissions, which wander across borders and negatively affect air law compiance.

For the EPA’s new good neighbor rules to work, the agency had to deny multiple state air plans and impose a federal alternative. Denials of state plans usually play out in regional courts, while challenges against federal alternative programs go to the D.C. Circuit, so this good neighbor legal battle is playing out in a patchwork of lawsuits across courts nationwide.

While the EPA continues to fight off lawsuits and deliberates on pollution standards for other common pollutants, advocates worry the gap in protection is widening as cumulative climate effects get worse.

“These things all add up, and given how long it takes not just to set a standard but also to implement it, it’s incredibly important for the EPA and the administration to move quickly,” Brown from Earthjustice said. “It has been a very concerning summer.”