eDNA could be used to measure pollen levels

Autonomous airborne pollen samplers might help to provide a breath of fresh air for asthma and hay fever sufferers, according to Australian and UK researchers.

Over 400 million people around the world suffer from allergic rhinitis, commonly known as hay fever. Another 300 million have asthma. But while grass pollen is known to be a common allergen, it hasn’t been clear which of more than 11,000 grass species cause the most trouble for human health. Researchers from the University of Exeter, Bangor University and The University of Queensland (UQ) have now suggested that environmental DNA could help us to better understand which grasses are the worst offenders.

“Previous investigations of airborne grass pollen have been constrained by the way in which concentrations of grass pollen in the atmosphere are typically monitored: using optical microscopy to identify and count pollen grains collected from aerial samplers,” said Francis Rowney from the University of Exeter. “Since grass pollen grains from different taxa are generally not distinguishable using optical microscopy, most epidemiology has focused on population exposure to total grass pollen concentrations and how they associate with allergy-related health outcomes.”

Rowney and his fellow researchers took a different approach, using environmental DNA (eDNA) sampling and quantitative PCR (qPCR) to measure the relative abundance of airborne pollen from common grass species over two seasons. Next, they looked for patterns between the prevalence of particular types of grass pollen and the incidence of severe asthma exacerbations as well as prescribing rates for allergy medicines. The results of their work were published in the journal Current Biology.

The data showed substantial variability in the relative abundances of airborne pollen from different grass species, both across the UK and over the course of the grass pollen season. The analyses also show that pollen from certain grasses may have a disproportionate influence on relevant health outcomes at the population level, as indicated by the number of prescriptions written for allergy medications as well as hospital admissions for asthma.

“We’ve known for a long time that grass pollen has important implications for health at population scales, but we didn’t really know very much about different types of grass pollen,” said Georgina Brennan from Bangor University. “This research suggests that there may be important differences in the public health impacts of pollen from different grasses. It suggests we should work to find out more and to consider whether the way we manage pollen health risks — such as warnings in the weather forecast — can be improved.”

“These findings represent a first step towards changing and improving our understanding of the complex relationships between pollen and population health,” added Benedict Wheeler of the University of Exeter. “If confirmed and refined, this research could help to improve pollen forecasts and warnings in the future, supporting individual and community-level prevention strategies and management of healthcare system responses.”

The researchers say they’d like to have broader spatial coverage and monitoring over a greater number of pollen seasons to get even more information about the relative impacts of individual grass species. Ultimately, they said they “envisage the development of a global network of autonomous aerial samplers, able to discriminate and quantify airborne pollen, allowing sensitive biomonitoring of important aeroallergens at high spatial and temporal resolutions”.

Image credit: Carsten A Skjøth.

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