How the massive Everglades fire affected air quality over South Florida

By Robert C. Jones Jr. [email protected] 09-02-2025

Fires that scorched nearly 50,000 acres in the Everglades during late August have been extinguished, but smoldering in the ashes are concerns about how smoke from future blazes in the River of Grass will affect air quality over South Florida, putting human health at risk.

"We can avoid certain exposures," said Cassandra Gaston, an aerosol scientist at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science. "We can choose to not eat contaminated seafood or to avoid certain dermal exposures. But we all must breathe air."

During the eight days that the massive Everglades wildfire burned, she and two members of her research group used a single-particle aerosol mass spectrometer, or SPAMS, to sample the air quality over their Virginia Key campus, discovering elevated levels of potassium, sulfates, and nitrates in the atmosphere.

"We mostly see emissions from the ocean and from the Rickenbacker Causeway," said Gaston, an associate professor of atmospheric sciences whose research group focuses on the physiochemical properties of aerosols that affect climate, the ecosystem, carbon cycling, and human health. "But during the Everglades fire, SPAMS picked up at least triple the number of particles we typically experience at the Rosenstiel School."

An air sampler device maintained by Paquita Zuidema, professor and chair of the Department of Atmospheric Sciences, also measured heavy concentrations of those chemical components in the smoke from the Everglades fire.

Though Gaston's team sampled air only over the University's Marine Campus, their readings serve as an accurate barometer of air quality for all South Florida during the time of the blaze. "We're an endpoint," she said of the Rosenstiel School's location on Virginia Key, a barrier island in Biscayne Bay. "The smoke traveled from the Everglades out toward the ocean. So, the whole area was being blanketed in smoke."

The team is still analyzing results from their sampling, comparing the quality of air in the atmosphere before and after the fire.

"We want to know what the wildfire aerosols look like," said James Christie, a Ph.D. candidate studying atmospheric chemistry and climatology. "What heavy metals are we seeing that might affect human health? And what's the size of those aerosols? And that's of particular importance because extremely fine particulate matter, usually less than 2.5 microns, can be indicative of something that could affect the blood and the lungs."

It was Christie and postdoctoral researcher Sujan Shrestha's idea to boot up SPAMS to sample the air when the Everglades fire started. "When smoke from the Canadian wildfires was making its way down, we did something similar to capture that event," he said.

Their findings on the chemical composition of the smoke from the Everglades conflagration could help health officials issue more accurate advisories for the public, especially for people with asthma and other respiratory conditions who are more vulnerable to the effects of smoke.

While air quality eventually improves after smoke events from wildfires, how quickly those conditions improve depends on the weather. "How fast are the winds dissipating the smoke? Is there a rain event? Rain tends to wash out a lot of the particle pollutants. So, the lingering effects [of smoke] really depend on the interplay between how much is being emitted and the underlying meteorological conditions," Gaston said.

Winds from Hurricane Erin, which swirled in the Eastern Atlantic Ocean at the time, blew smoke from the fire across South Florida, she noted. "And it hadn't rained in a while, which can keep emissions in the air longer," she said. "And smoke, some studies have found, can be more toxic to human health than emissions from fossil fuels."

A NASA study using satellite observations and advanced computing found that extreme forest fires in 2023 released about 640 million metric tons of carbon-comparable in magnitude to the annual fossil fuel emissions of a large, industrialized nation.

With dense brush that can quickly dry out, the Everglades are especially susceptible to wildfires that can be ignited by lightning strikes. So, more fires in the River of Grass will surely occur, Gaston said.

"Most of the research on the impacts of smoke from fires has focused on huge wildland fires on the U.S. West Coast. We don't know as much about fires in the Southeast, whether they be lightning-induced or prescribed burns," Gaston said.

Controlled burns are crucial to the Everglades, helping to clear grasses and keep water flowing through the marshes. "But there's a lot of questions right now about prescribed burn practices. They're obviously an important component in shaping the landscape, but how do we conduct them in a way that's going to be most beneficial and have the least impacts on air quality? And that's where our measurements could be of use," Gaston said.

"No two fires are the same, which makes it a challenge to forecast the impacts of smoke," Shrestha said. "We're currently analyzing data from this most recent Everglades fire. But looking at the wildfires that occurred in Los Angeles earlier this year, the smoke from those fires gave off a different signature."

Growing up in a valley in Nepal, Shrestha witnessed firsthand how urbanization impacted the air quality in his community, often standing on the rooftop of his home to look at polluted skies. "That made me inquisitive about air quality, and that's how I got started in this area of research," he said. "The measurements and data that we've collected from the Everglades fire is important because we can help people at risk."