“We looked into the atmospheric levels of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs) over the years, at an agricultural site in the Czech Republic. A few things stood out, for instance, concentrations of some OCPs declines over time, we found that concentrations of key pollutants like β- and γ-HCH, DDT , α-chlordane, and mirex are leveling off, which means that secondary sources, such as soil and bodies, are enhanced and release these pollutant s back to the environment over time, especially in the summer,” says main author of the publication Ludovic Mayer.
The researchers also observed that CUPs atmospheric levels mostly decreased or showed no significant changes over time, but critically, banned substances like chlorpyrifos and fenpropimorph remained detectable in the atmosphere even years after their bans took effect, highlighting their persistence.
“Our research is vital because it challenges the assumption that highly persistent banned substances disappear naturally over time; the leveling off of OCPs concentrations proves that decades-old pollution sources continue to contaminate our air, posing ongoing risks to human and environmental health. We established that environmental loads of these semivolatilecompounds persist because they degrade much slower in soils and have the capacity to revolatilise over time,” adds Ludovic Mayer.
Moreover, tracking current-use pesticides provides immediate feedback on the effectiveness of recent bans, showing that compounds like chlorpyrifos and fenpropimorph persist in the atmosphere years after they were prohibited, indicating a need for continued vigilance regarding environmental clearance and human exposure to these toxic substances. The study highlights the importance of continued long-term monitoring for CUPs, which is currently lacking, but would provide sufficient insights into their atmospheric fate and to develop accurate models to predict key environmental processes like transport and deposition.
The conclusions were reached by performing continuous biweekly air sampling at the National Atmospheric Observatory Košetice (NAOK), a rural-agricultural site in the Czech Republic, spanning 10 years for OCPs and three years for CUPs.
“We collected air samples with large air pumps that pull outdoor air through special filters, allowing us to capture both airborne particles and the pesticides that exist as gases. In the lab, we used sensitive instruments to identify and measure these pesticides very precisely. We then applied statistical methods to see how pesticide levels changed over the years and how factors like temperature affected their release back into the air from surfaces such as soil.
These findings help us better understand how pesticides behave in the environment, and they show why long-term monitoring is essential. In the future, we hope to study a wider range of chemicals and also look at the interaction, not just with air, but in soil, water, and rain/snowfall. That way we can get a clearer picture of the cycling of those compounds in the environment,” concludes Ludovic Mayer.
Learn more: https://doi.org/10.5194/acp-25-12467-2025
