What defines a heat wave? The answer could decide where disaster dollars go.

Another brutal summer is shattering temperature records, broiling over a third of Americans under extended heat advisories. As smoke from wildfires begins to choke skies and death counts tick upwards, affected states say they need more help from the federal government.

During most climate-driven emergencies, such as hurricanes or floods, local governments can rely on the Federal Emergency Management Agency to fund relief efforts. But heat waves and wildfire smoke aren’t explicitly listed as “major disasters” under the law that empowers FEMA to administer emergency aid and don’t fit neatly within the disaster-declaration process — leaving affected communities without a clear pathway to access funds. Recently, in response, states and advocacy groups have been pressuring FEMA to treat heat waves and wildfire smoke as the major disasters they are.

Part of the problem comes down to semantics, and how climate-impacted events are addressed — or, more precisely, not addressed — in a 1988 law called the Stafford Act, which authorizes FEMA to administer a wide range of assistance to local and state governments following a major disaster declaration from the president. Despite listing 16 specific disasters that qualify for this declaration and the funding it unlocks, neither heat waves nor wildfire smoke are mentioned in the text of the law.

FEMA says that dangerous heat and smoke from wildfires could still qualify for major disaster declarations under what the Stafford Act refers to broadly as “any natural catastrophe.” But only three major disaster-declaration requests for heat have ever been made — all of which were rejected. Still, the agency insists heat waves and wildfire smoke are given the same level of consideration as any other disaster.

“We take every severe weather event on a case-by-case basis to understand what the impacts are to the community and what they might need from the federal government,” said FEMA Administrator Deanne Criswell in an interview with Grist. But, she added, states need to demonstrate that they’re unable to shoulder the costs on their own before FEMA will step in.

Clearing that bar hasn’t been easy, as states may struggle to make use of the funds they already have. Last summer, for example, the governor of Arizona declared a state of emergency following a statewide extreme heat event, freeing up $200,000 through the Arizona Department of Emergency and Military Affairs to help reimburse local governments for their expenses. In the end, less than 1 percent of that money was spent, due to difficulty documenting costs associated with heat, complicated rules, and poor timing.

“Our disaster framework is really geared toward protecting property and counting up damages to property,” said Juanita Constible, a senior climate and health advocate at the National Resources Defense Council. She said that because of the diffuse way heat harms human health, it’s tough to put a price tag on the toll on a community, and the death count isn’t always clear until the worst of the summer is over. Unlike the calculable wreckage of hurricanes or floods, proving financial losses from heat with health data is “much more challenging,” she said.

“There’s no quick way of tallying up the damages and demonstrating, ‘This was way too hard for us, we need your help stat,’” Constible said. She added that FEMA requires clear and specific data that documents expenses incurred during a heat wave or smoke event, which is difficult for states to provide using existing tools meant to track impacts from heat or smoke.

Tourists find shade from the sun at a cooling station, which blows cold air-conditioning and sells water, at the Hoover Dam in Boulder City, Nevada, during a heat wave in June. Jim Watson / AFP via Getty Images

Another roadblock to accessing federal aid in the wake of a heat wave or wildfire smoke is determining exactly when an event begins and ends. Whereas some disasters happen in a single powerful event, like an earthquake or a tornado, high temperatures and smoky skies can drag on for weeks. Because of this, said Constible, heat does not “fit nicely” within a typical disaster declaration process.

As climate change fuels more intense, prolonged heat waves that kill more people than any other kind of weather event, cities like Phoenix could end up losing billions of dollars per year from infrastructure damage and the loss of life and workforce productivity. Last year, over 600 people died from heat in Maricopa County, which includes Phoenix, and by mid-July this year, dozens more residents had suffered the same fate.

Pressure for FEMA to make a change to how it approves disaster aid is mounting. Last month, a multistate coalition of environmental, labor, and health organizations filed a petition to the agency, asking for amended rules that explicitly recognize extreme heat and wildfire smoke as major disasters and clear the way for getting funding requests approved. It also detailed how funding from a major disaster declaration could be used to mitigate the harmful effects of heat and wildfire smoke.

That initiative was followed last week by a July 16 letter from attorneys general in 13 states and Washington, D.C., in support of the petition. Oregon Attorney General Ellen Rosenblum, who signed the letter, said in a statement to Grist: “We need the federal government to keep up with the realities Oregonians face, and we need FEMA to have the jurisdiction to assist when we ask for help.”

Earlier this month, lawmakers Dina Titus of Arizona and Greg Stanton of Nevada — U.S. representatives from two of the hottest and hardest-hit states — introduced a bill that expands how FEMA can respond to these events.