Thunderstorm asthma
Thunderstorm asthma refers to storm activity triggering an increase in people reporting asthma symptoms and seeking medical attention for breathing issues.
Applies to England
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Topic: environmental exposures
Air-related exposure: airborne allergens
Part of: The Health Risks of Airborne Allergens
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Thunderstorm Asthma
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About thunderstorm asthma
Thunderstorm asthma occurs when thunderstorm activity is linked to an increase in people reporting asthma symptoms and seeking medical attention for breathing issues. It has been observed since the 1980s, with notable events in Birmingham (UK) in 1983, and a severe event in Melbourne (Australia) in 2016, which overwhelmed the city’s ambulance system and resulted in 10 deaths (1).
As the climate changes, there is good evidence that earlier and longer growing seasons may lead to higher concentrations of airborne allergens (pollen and spores) (2). Furthermore, increased concentrations of carbon dioxide have been linked to an increased spore count of allergenic fungi and more atmospheric pollen.
People affected by thunderstorm asthma
Everyone can be at risk of thunderstorm asthma, but young adults under 30 are more likely to be affected. There is also some limited evidence that people who have asthma (both diagnosed and undiagnosed), and those who have hay fever, are also more at-risk from the impacts of thunderstorm asthma.
Causes of thunderstorm asthma
The phenomenon of thunderstorm asthma is widely recognised as a potential risk for public health in the UK but is not fully understood. It is believed that the airflows created by pressure within a thunderstorm system plays a crucial role. Thunderstorms form when warm, wet air on the earth’s surface rises quickly, causing cooler air to flow down towards the ground. This process generates strong surface winds that pick up pollen grains and fungal spores. These particles are then thought to be pulled up into the storm system, where they break apart into smaller granules due to excess moisture in the clouds. Rain then brings these tiny particles down to ground level, where they can be inhaled deep into the lungs, causing breathing problems.
There are also environmental factors linked to thunderstorm asthma events, including the high levels of pollen or fungal spores, generally following a period of warm and humid days.
How UKHSA monitors incidences of thunderstorm asthma
The UKHSA’s syndromic surveillance systems monitors data from sources including NHS 111 calls, GP consultation tracking, emergency department attendance and ambulance services. By examining these data sources, UKHSA identifies trends indicating higher-than-usual levels of illness and publishes bulletins to keep public health professionals informed. Through this monitoring system, several potential episodes of thunderstorm asthma were detected in June 2021 and again a year later on 11, 12 and 18 June 2022.
Figure 1. Thunderstorm asthma infographic
Source: Severe Asthma Toolkit (3)
This infographic shows that during high pollen seasons, thunderstorm winds and moisture break pollen grains into tiny particles, which are then blown near ground level and inhaled deeply into the lungs, triggering asthma attacks. It highlights who is at risk (people with asthma and allergies or hay fever), although sudden asthma symptoms can be caused even in people without a prior asthma diagnosis. It also lists prevention tips such as taking asthma medication, managing hay fever, and staying indoors during storms.
References
(1) UK Health Security Agency, ‘Adverse Weather and Health Plan Supporting Evidence’ , 2024 (Viewed 25 March 2025)
(2) Thompson R, O’Connell E, Elliot A, ‘Thunderstorm asthma and public health – looking back to move forward – UK Health Security Agency’ , 2022 (Viewed 25 March 2025)
(3) Severe Asthma Toolkit, ‘Severe Asthma Infographics’ (Viewed 7 May 2025)