Hay fever and asthma sufferers are likely to be enduring more severe symptoms at this time of year due to widespread use of nitrogen to fertilise crops in Ireland, according to a new study.
Commenting on the report, published in The Lancet Planetary Health, leading pollen researcher Dr David O’Connor said increased nitrogen levels “lead to higher concentrations of allergenic pollen, exacerbating allergic reactions such as hay fever and asthma”.
O’Connor, of Dublin City University’s School of Chemical Sciences, said the research showed that grassland where nitrogen fertiliser is spread produces six times as much pollen as non-fertilised lands, while fertiliser-produced pollen will also produce a stronger allergic response.
People with hay fever and asthma living in rural areas close to places with higher nitrogen fertiliser application rates will be the most affected, he said, but urban dwellers will also feel the impact as pollen from nitrogen-fertilised grasslands can be carried on the wind into towns and cities.
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Meanwhile, the use of nitrogen fertilisers in Ireland has been increasing.
“In 2024, Irish farmers applied approximately 310,411 tonnes of chemical nitrogen fertilisers; a 10.6 per cent increase from 2023,” said O’Connor, who is setting up a pollen monitoring network with Met Éireann, to help the large numbers of people in the State who suffer pollen-related allergies.
Hay fever affects 26 per cent of adults in the Republic, while about 450,000 people in the State have asthma. One of those is Edel Abberton a former nurse and a full-time carer of two autistic children, in Galway, who has severe hay fever and asthma.
“When I start to get sick I can deteriorate very quickly, so luckily I have a very good GP who knows me, and doesn’t really take a chance on me,” said Abberton, who lives in a part of the city that is close to agricultural land.
“The hay fever for me is very interconnected with my asthma. The hay fever plays up, my asthma plays up – because it’s all your nose and your mouth. It can make you feel quite tired when you are struggling with that,” she said.
Abberton was not aware of a link between fertilisers and pollen levels, but said she has noticed that both her conditions worsen in springtime, coinciding with when many farmers begin spreading fertilisers.
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“In the last three to four weeks, I’ve noticed it again getting worse,” she said. “You can feel it, which would fit in with the nitrogen. You can sense it.
She called for “better education across the board” to raise awareness of the issue, including among farmers.
The study, which was conducted in Belgium, compared pollen samples from nitrogen-fertilised and non-fertilised grasslands. The average pollen found was found to be 6.2 times higher in fertilised lands.
The scientists also tested how allergenic, or likely to produce an allergic response, the pollen from fertilised fields was. They took blood from 20 people then exposed it to pollen from fertilised as well as the non-fertilised land. They found that people were five times more sensitive to the former.
The authors of the study say it is the first to prove a clear link between nitrogen fertilisers, higher pollen counts and the ability to trigger allergies.
“The findings highlight an urgent need for strategies to not only address nitrogen fertiliser’s impact on biodiversity and the environment, but also the human health impact posed by nitrogen pollution,” the scientists said.
