Analysis: certain weather conditions, such as thunderstorms, affect and aggravate the amount of the pollen in the air

By Emma Markey and David O'Connor, DCU

It is that time of the year again: the days are at their longest, temperatures are rising and exam season has come and gone. Unfortunately, unlike the Leaving Cert, which only causes pain and suffering over a three-week period, the grass pollen season is set to do so over the full summer.

Pollen is generally released during good weather conditions (warm, sunny, windy days) but is seen in the atmosphere year-round. This is because different plant species (tree, grass, weed etc.) release their pollen at different times of the year.

Grass pollen in the dominant pollen species in the summer months. It is responsible for the majority of allergies known as "hay fever" and has a cocktail of symptoms associated with it. However, unlike a fruity sangria, this cocktail manifests as sneezing, coughing, itchy/watery eyes, sinus pain (headaches, earaches) and just general feelings of lethargy.

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From RTÉ Brainstorm, why hay fever will get worse

Interestingly, it is not the pollen grains themselves that are responsible, but rather the presence of certain molecules (proteins) within the pollen grain that are released when we breathe them in. While the release of pollen is a natural and necessary process, anyone that suffers from these symptoms will experience a significant influence on their overall wellbeing.

While hay fever (or allergic rhinitis for those in the allergy prediction and mitigation business) can impact people's health, pollen poses a particular risk to the Irish public with respiratory diseases such as asthma. Ireland has the fourth highest rate of asthma in the world with up to 80% of Irish asthmatics also suffering from hay fever. This is particularly concerning since exposure to airborne pollen has been shown to seriously exacerbate asthma.

We can generally assume that pollen concentrations (grass pollen) will be higher in the summer, with nice sunny days linked with high pollen concentrations and rainy days associated with low pollen concentrations. However, thanks to recent research, we now know certain weather conditions, not traditionally connected with hay fever, may actually affect the amount of the pollen allergen in the air. This serves up one of those nasty summer cocktails when you least expect it.

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From RTÉ Radio 1's Drivetime, Prof Jonathan Hourihane from the RCSI on why hay fever levels are rising

When we do eventually get good, sunny weather, it usually comes to a crashing end with the inevitable onslaught of rain and wind. When we couple warm weather with stormy conditions, we get the ingredients needed for a thunderstorm. Here in Ireland, we tend to see a flurry of thunderous activity during mid-to-late summer. You might assume that these stormy conditions would put an end to your grass pollen suffering, but you couldn’t be more wrong.

When thunderstorms form following high pollen counts, winds carry the pollen grains high into the sky where they encounter moist air. This moisture is enough to burst the pollen grains, releasing hundreds and thousands of tiny allergenic particles, way more dangerous than the original pollen grain. These particles can travel deeper into your lungs and cause more severe allergic reactions.

As the storm continues, these allergenic pollen particles which would normally be high in the clouds and out of harm’s way, get forced down towards the ground and are kept circulating by the wind so there is a constant cycle of irritation. The resulting hay-fever is known as "thunder fever".

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From SciShow, how a storm triggered a city-wide asthma attack

This "thunder fever" is particularly dangerous for those that suffer from asthma as these small pollen particles can trigger very severe attacks. These asthma attacks are more commonly referred to as "thunderstorm asthma".

It almost sounds like the title of a corny disaster film, but I assure you this is no joke. Thunderstorm asthma is a very serious condition. If you find yourself wheezing and sneezing your way through summer, there is even a chance that you could develop thunderstorm asthma even if you've never had asthma before. This condition is known all too well in other countries that also have very high rates of asthma like Australia, where the summer months are fraught with distress

In 2016 in Victoria in southeastern Australia, the combination of thunderstorms and high grass pollen concentrations led to a thunderstorm asthma disaster. Thousands of people suddenly began to have asthma attacks and were struggling to breathe; some 40% of these had never experienced asthma before. As a result of thunderstorm asthma, many were hospitalised and nine people died. This incident was cemented into the history books as the worst episode of thunderstorm asthma ever recorded worldwide and highlighted thunderstorm asthma as a force to be reckoned with.

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From Better Health, Christine McDonald, Director of Respiratory and Sleep Medicine at Austin Health, explains what causes thunderstorm asthma

So how do you make sure you don't star in that corny "thunder fever" disaster movie? Well, If you are affected by hay fever or asthma, it is very important you take necessary precautions during thunderstorms and high pollen concentrations, such as making sure you have access to relieving medication. Similarly staying indoors with the windows closed to avoid exposure can be a good prevention. So no singing in the rain (or just after the rain) for you.

A simple mitigation technique like having Vaseline around your noise can trap pollen grains before they enter your system. Finally, wearing a mask can be a great way to lower the amount of these particles breathed in. Just as with Covid, a high-grade mask can be a very effective option in protecting against such allergen-causing particles. Let’s all hope "thunder fever" doesn’t do well at the box office this summer and that the only cocktail that we encounter is a refreshing sangria.

Emma Markey is a PhD student at the School of Chemical Sciences at DCU and is a Irish Research Council Government of Ireland Postgraduate awardee. Dr. David O'Connor is an assistant professor at the School of Chemical Sciences at DCU. He leads a research group currently focussing on establishing an Irish Bioaerosol monitoring network.


The views expressed here are those of the author and do not represent or reflect the views of RTÉ