A new study published in December 2024 found that even wildfires more than 2,000 miles away can trigger sharp increases in cardiopulmonary symptoms and emergency department visits.¹

This has life-threatening implications for the millions of people in the Los Angeles area and beyond who have been fighting a series of unforgiving wildfires since January 7. For many individuals with existing respiratory issues, the smoke damage can be as equally dangerous as the fire itself.

“I treat veterans in a pulmonary clinic, and on high smoke days, my patients were saying, ‘I can’t breathe,’ but there wasn’t a lot of good data on the health effects of wildfire smoke here in the East,” said Mary E. Maldarelli, MD, a pulmonary and critical care fellow and postdoctoral fellow in epidemiology and public health at the University of Maryland School of Medicine. “Unlike the West, we never see large wildfires and previously never saw wildfire smoke.”

That changed in June 2023, when Canada had a record-breaking wildfire season with more than 6,500 fires across more than 45 million acres of forest. Baltimore, like much of the Eastern US, was shrouded in smoke plumes from wildfires as far as 2,100 miles to the west.

Air quality across Maryland plummeted as concentrations of particulate matter 2.5 microns and smaller (PM_2.5) exceeded the toxic National Ambient Air Quality Standard of 35 μg/m.² PM_2.5 concentrations during those hotspot days of toxic air quality in Baltimore were up to 9.4-fold higher than other days. Clinicians knew to expect increases in patient visits and cardiopulmonary symptoms following high smog days, Dr. Maldarelli said, but distant wildfire smoke was a new exposure with virtually no analogues in the literature.

The research showed that compared with identical control days in prior years without wildfire smoke exposure, medical visits for cardiopulmonary symptoms increased by 18% during hotspot periods. Looking at cardiac symptoms only, there was a 20% increase in the likelihood of a medical encounter associated with wildfire smoke exposure.

“I grew up with a lot of Code Red days when it was very hot and there was bad smog in the city,” Dr. Maldarelli said. “I don’t know if you can precisely extrapolate the physiologic effects from wildfire smoke to the effects of smog because they are different sets of chemical compounds, but I had the opportunity to talk with researchers in California about their experiences with cardiopulmonary diseases on high smoke days. We saw the same effects.”

The data show wildfire smoke exposure produces similar cardiopulmonary symptoms whether the smoke source is next door or a continent away. As temperatures rise and wildfire risk increases, so does the risk of exposure to wildfire smoke from near and distant fires.

According to the US Environmental Protection Agency, climate change has already increased the frequency and intensity of wildfires, which will lead to more exposure to wildfire smoke. Patients with a history of asthma, COPD, and cardiovascular disease are at a higher risk for adverse health consequences related to wildfire smoke exposure.

“Other parts of the country, particularly the West, see wildfire smoke every year,” Dr. Maldarelli said. “Our state had never seen this before, at least not in my lifetime. We never see large wildfires or get wildfire smoke because we don’t have the same climate, geography, and forest growth. My patients are now seeing novel inhalational exposures to wildfire smoke that have never been seen before in Maryland. This shows us we really are a global community, and climate events that happen in other parts of the country, in other countries, affect us here.”

The next step for Dr. Malderelli’s group is an economic analysis of the dollars and cents cost of the 2023 wildfire smoke exposures in Baltimore. Dr. Maldarelli said she hopes the financial impact will spur policymakers to look for novel interventions to reduce the toll of future smoke and other climactic events.

“We have shown that there are people who didn’t get the care they needed during those high smoke days,” she said. “How do we help the system help them? If we send masks to people or take other steps, can we effectively reduce the health burden, deliver better care, and reduce overall costs with the next event?”

For more details on how climate change is negatively affecting pulmonary health, read the article “Where There’s Fire, There’s Smoke” in CHEST Advocates.

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References

1. Maldarelli ME, Song H, Brown CH, et al. Polluted air from Canadian wildfires and cardiopulmonary disease in the Eastern US. JAMA Netw Open. 2024;7(12):e2450759. PMID: 39671196. PMCID: PMC11645649. doi: 10.1001/jamanetworkopen.2024.50759

2. Thilakaratne R, Hoshiko S, Rosenberg A, Hayashi T, Buckman JR, Rappold AG. Wildfires and the Changing Landscape of Air Pollution-related Health Burden in California. Am J Respir Crit Care Med. 2023;207(7):887-898. doi:10.1164/rccm.202207-1324OC