Wildfire smoke creates invisible ozone risks for climate and health

Recent scientific studies highlight the secondary environmental and health impacts of wildfire smoke, specifically regarding ground-level ozone formation.

In the Amazon, research published in Communications Earth & Environment indicates that smoke from fires reduces the forest's ability to absorb carbon. This occurs because ozone formed from smoke reacts with sunlight in the troposphere, damaging the leaves of surviving trees and impairing photosynthesis. On average, for every 100 tons of CO2 emitted by fires, an additional 24 tons are not captured due to this ozone effect. This damage is intensified during droughts, such as the 2023/24 El Niño period, where ozone-related damage nearly doubled compared to the previous decade's average.

Separately, research published in Science suggests that wildfire emissions are reversing progress in air quality management. In the United States, increased wildfires between 2022 and 2024 exposed an estimated 43 million people to ozone levels that failed to meet federal air quality standards. Unlike visible smoke particles, ground-level ozone is an invisible pollutant linked to respiratory and cardiovascular issues, including asthma and lung disease. The studies emphasize that even after visible smoke clears, the chemical impact on ozone can persist, posing a continued risk to human health.