Does Nitrogen Fertilizer Increase Pollen Allergies?

Recent research indicates that nitrogen fertilizer application in grasslands could be significantly influencing pollen production and allergenic potential, potentially exacerbating allergy symptoms worldwide. A study published in The Lancet Planetary Health revealed that grasslands enriched with nitrogen produce up to six times more pollen than those without fertilizer treatment. Moreover, pollen from fertilized areas appears to be more likely to trigger hay fever, suggesting a direct link between nitrogen use in agriculture and increased allergy risks.

Over the past few decades, the prevalence of pollen allergies has surged globally. While atmospheric nitrogen pollution has been recognized as a contributor—affecting pollen release and allergen content—little research has focused on how nitrogen fertilizers themselves impact pollen production and allergenicity. To shed light on this, scientists compared pollen samples from 25 nitrogen-fertilized and 25 non-fertilized grasslands in Belgium.

The findings were striking: fertilized grasslands produced an average pollen count of 3.6 mg/m², which was more than six times higher than the 0.6 mg/m² from unfertilized grasslands. Meanwhile, tests exposing immune cells from 20 individuals to these pollen samples demonstrated that immune responses—specifically basophil sensitivity—were five times stronger to pollen from fertilized areas. This suggests that pollen from fertilized grasslands is not only more abundant but also more allergenic.

The researchers emphasized the importance of further studies involving actual exposure of participants to pollen to verify how these differences translate into allergy symptoms. They highlight that this research is the first to establish a clear connection between nitrogen fertilizer use and increased pollen count and allergenic potential. These findings underscore the need for strategies to reduce nitrogen pollution, not only for environmental and biodiversity conservation but also for protecting human health from allergy-related issues.

Overall, the study calls attention to the broader health impacts of nitrogen fertilizer usage, advocating for more sustainable agricultural practices that consider the implications for allergen exposure and public health.