The study was carried out by researchers from the University of Bristol and the Central Laser Facility at the Science and Technology Facilities Council (STFC).
The finding explains why 2,4-Dinitrophenol (DNP), a chemical compound toxic to plants, animals and humans, can remain active in the atmosphere for longer periods than previously understood.
This persistence may help explain why brown carbon from wildfires contributes to global warming for extended periods.
Understanding DNP’s atmospheric behaviour
The research team investigated how environmental conditions affect DNP’s lifespan in the atmosphere.
They found that when DNP dissolves in tiny airborne water droplets that make up mist and clouds, it becomes more resistant to the natural oxidation process that would normally break it down.
Toxic to climate and public health
DNP enters the atmosphere through multiple sources, including forest fires.
Once airborne, as part of brown carbon particles, DNP absorbs sunlight and converts it to heat, contributing to climate change.
The compound is also toxic to living organisms, making its extended atmospheric lifetime a dual concern for both climate and public health.
Sources of DNP beyond wildfires
Beyond wildfires, DNP is also produced by:
- vehicle emissions from both biofuels and fossil fuels
- residential heating fires and bonfires
- controlled agricultural burning
The broader impact of brown carbon
Brown carbon is a brownish smoke released when organic matter like forests burn and contains dangerous levels of organic chemicals that cause both short and long-term health problems.
An estimated 1.5 million people are killed annually because of wildfire smoke exposure.
The research comes as wildfire frequency increases globally, with four of history’s five worst years on record occurring since 2020.
Unusual wildfire locations such as the UK and Sweden highlight the expanding impact of climate change.
Research implications
By understanding the mechanisms that extend DNP’s atmospheric lifetime, researchers may identify methods to reduce how long these harmful compounds remain active in the environment.
This knowledge could inform both air quality management and climate modelling efforts.
Dr Igor Sazanovich, Senior Scientist at the STFC Central Laser Facility, said:
Our advanced laser techniques allowed us to observe exactly how DNP behaves at the molecular level when it encounters atmospheric water droplets.
What we discovered was surprising, the droplets actually shield these toxic compounds from breaking down. This finding could change how we model the persistence of wildfire pollutants in our climate systems.
The study was published in scientific journal ‘Proceedings of the National Academy of Sciences’ on 4 August 2025.
