Study - Sunlight Interacts W. Wildfire Smoke, Altering Toxicity & Worsening Lung Cell Death
Wildfire season is getting longer and more severe. The fires send smoky gases and fine particles of burnt matter drifting through the atmosphere, and their harm can be felt by lungs miles away. It’s plain that wildfire smoke is harmful, and studies have linked smoke inhalation to inflammation, cell death, and lung diseases, including asthma. But figuring out the connection between smoke inhalation and ill health is tricky—wildfire smoke comprises a complex mixture of particles and gases, and once in the atmosphere, photochemical reactions transform those components into different substances. But a research team from the University of Georgia might have a lead after testing how fresh and aged smoke differentially exerted their toxic effects.
As wildfire smoke rises into the atmosphere, sunlight spurs chemical reactions that alter the smoke’s original components (primary organic aerosols) and create new ones, so-called secondary organic aerosols, over the course of hours to days. “That smoke is hanging out there for days and days and days, and it’s getting chemically cooked,” said Anthony Wexler, a professor and the director of the Air Quality Research Center at the University of California, Davis. Wexler was not involved in the new study. “And there are interesting questions there about how that’s changing the toxicity of this stuff.”
Once they enter human airways, the different aerosols likely take different routes through the body. Secondary organic aerosols are generally more oxygenated and soluble than primary ones. Primary organic aerosols are more readily taken up by fats, whereas secondary organic aerosols better dissolve in the bloodstream. But when Rawad Saleh began researching the health effects of wildfire emissions at the University of Georgia’s College of Engineering, the associate professor was surprised by the dearth of information on how wildfire smoke toxicity changes as the smoke itself changes in the atmosphere.
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After reacting with UV light in the environmental chamber, the aged smoke from each wood differed from fresh smoke in several key ways. Aged smoke had fewer heavy metals and aromatics but did have more heavily oxygenated compounds. This, the researchers thought, drove different toxicity mechanisms. The fresh smoke’s aromatics and metals homed in on the cellular powerhouse, mitochondria, disrupting the way cells store and use energy. But in the aged smoke, oxygenated compounds led to higher levels of cell death.
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https://eos.org/articles/the-sun-bakes-wildfire-smoke-changing-its-toxicity
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