New KAUST Study Reveals Sunlight's Role In Increasing Wildfire Smoke Pollution

Wildfire smoke contributes to more air pollution than previously predicted by atmospheric models. A study in Science Advances uncovers the chemistry behind this. Researchers from King Abdullah University of Science and Technology (KAUST) and the Chinese Academy of Sciences found that wildfire smoke particles, when exposed to sunlight, become chemical factories. They produce harmful oxidants like peroxides, which are reactive pollutants contributing to smog and haze.

The study highlights how these particles can bypass traditional suppression by nitrogen oxides in polluted areas. Under sunlight, they generate oxidants internally. Professor Chak Chan from KAUST noted, "This particle-driven pathway is surprisingly efficient and faster than what classical pathways can supply." This discovery underscores the need for updated atmospheric models to better predict health risks and environmental impacts.

Colored organic molecules in biomass-burning aerosols act as photosensitizers. When they absorb sunlight, they enter excited states that trigger rapid reactions. These reactions produce peroxy radicals and then peroxides inside the particles. Although peroxides are not greenhouse gases, they influence atmospheric chemistry by driving haze and secondary particle formation, impacting respiratory health.

The findings show how wildfire smoke contributes to secondary particulate matter formation, adding to urban air pollution. Wildfires have significantly increased in size in parts of the western United States since the 1980s. Similarly, Mediterranean burn areas have more than doubled over the past two decades. As fires grow more frequent and intense globally, their smoke becomes a hidden source of air pollution worldwide.

The research also explains why field measurements detect high peroxide levels during wildfires, even in cities where normal chemical routes should be blocked by other pollutants like nitric oxide. This understanding is crucial for communities, including those in Saudi Arabia, to anticipate global warming's health risks and environmental impacts better.

By acting as radical reservoirs, peroxides affect broader climate and air-quality dynamics. The study emphasizes the importance of updating atmospheric models to reflect these findings accurately. This update is vital for predicting future scenarios related to global warming and its effects on human health and the environment.

With inputs from SPA