Written by Nancy Lapid
(Reuters) – Wildfires are raging in Los Angeles, engulfing surrounding counties in heat from smoke that carries dangerous gases and particulates that pose a health risk.
Here’s what you need to know about the potential dangers of smoke not only in southern California but in other regions around the world where wildfires are burning:
WHAT IS CONTAINED IN THE FUEL OF FIRE?
More toxic than regular air pollution, wildfire smoke can linger in the air for weeks and travel hundreds of miles.
Wildfires can burn not only vegetation and trees but also cities, destroying cars and buildings and the environment. Along with soil particles and organic matter, wildfire smoke often contains traces of chemicals, metals, plastics and other synthetic materials.
WHAT ARE THE KNOWN HEALTH EFFECTS?
In laboratory tests, a given amount of wildfire smoke causes more inflammation and tissue damage than the same amount of air pollution, according to Kent Pinkerton, co-director of the Center for Health and the Environment at the University of California, Davis.
Studies have linked wildfire smoke to higher rates of heart attacks, strokes, and cardiac arrests, increased emergency room visits for respiratory conditions, and weakened immune systems. A study conducted in Maryland identified heart and lung disease in 2023 that was associated with wildfire smoke from a distance of 2,100 kilometers (3,380 km) in Canada.
Wildfires have also been linked to eye irritation and skin problems.
The effects of exposure can last for years. After Australia’s Hazelwood Coal Mine fire of 2014, heart disease rates remained high for two and a half years and respiratory diseases for five years, researchers have reported.
Wildfire exposure in pregnancy has been associated with pregnancy loss, low birth weight, and preterm delivery. A study from California found a link between wildfire exposure and cellular damage in first- and second-trimester placentas.
Canadian researchers reported that people who lived outside of major cities and within 50 kilometers (31 miles) of wildfires in the past decade had a 4.9% higher risk of lung cancer and a 10% higher risk of brain tumors.
Exposure to the 2018 Camp Fire in California was linked to changes in cognitive function and cognitive function six to 12 months later, possibly related to stress and trauma, according to California researchers.
Data from California also shows an increase in fungal infections in the months following exposure to wildfire smoke, possibly due to fungal spores in the smoke.
High exposure to wildfire smoke is also associated with a higher likelihood of developing dementia, according to a study of Southern California adults without early dementia. Even “a few days of really intense wildfire smoke,” with an Air Quality Index of more than 200, could add to the risk, said Joan Casey of the University of Washington in Seattle, who led the study.
WHAT IS NOT KNOWN?
More frequent wildfires related to climate change mean that people will be exposed more often and the health effects of wildfire smoke exposure over many seasons are still unclear.
“Repeated exposure is more likely to cause disease, but it is difficult to predict because it is difficult to say how many fires people will be exposed to, how long the fire will burn, or what the smoke will contain,” said Keith Bein. of the Center for Health and the Environment at UC Davis.
Researchers are also looking at the long-term effects of smoke particles on water, plants or ingested by livestock; long-term effects of urban fire smoke; effects of wildfire exposure in utero on infant neurodevelopment and respiratory outcomes; and whether wildfire smoke amplifies the adverse effects of extreme hot weather.
Nutrients carried by wildfire smoke may contribute to algal blooms, which affect drinking water and lake ecosystems, researchers warn.
WHAT CAN HELP REDUCE THE RISK?
Experts say it is best to limit outdoor activities, especially strenuous sports, and to wear an N95 mask when there is wildfire smoke.
An online course with instructions for reducing outdoor and indoor exposure to wildfire smoke is available from the US Environmental Protection Agency.
DO WE REALLY NEED TO BE WORRIED?
Doug Brugge, who chairs the Department of Public Health Sciences at the UConn School of Medicine, said wildfire smoke can be deadly. “People should… reduce their exposure, especially if they are in vulnerable areas, such as the elderly, young children or people with respiratory diseases.”
