NHS Thunderstorm Warning: People With These Conditions Could Face Worse Symptoms
Thunderstorms may look dramatic, but for some people they can bring a less obvious health risk. People with asthma and hay fever are being urged to take extra care when storms arrive, as changes in wind, humidity, pollen and fungal spores can trigger breathing problems.
The phenomenon is known as thunderstorm asthma, and health authorities say it can cause a sudden increase in asthma symptoms and breathing difficulties.
Although thunderstorms do not affect everyone in the same way, people with certain respiratory and allergy-related conditions may be more vulnerable. The risk can be particularly important during periods when pollen levels are already high.
What is thunderstorm asthma?
Thunderstorm asthma describes an increase in asthma symptoms and breathing problems associated with thunderstorm activity.
According to the UK Health Security Agency (UKHSA), the exact causes are not completely understood. However, scientists believe that a combination of strong winds, humidity, pollen and fungal spores can contribute to an episode.
When a thunderstorm develops, warm, moist air can rise quickly while cooler air moves down towards the ground. This creates strong winds that can pick up pollen and fungal spores.
Moisture inside storm clouds can cause pollen grains and fungal spores to break into much smaller particles. Rain can then bring these tiny particles back towards ground level, where they may be inhaled more deeply into the lungs.
For people with sensitive airways, this can contribute to coughing, wheezing, chest tightness and breathlessness.
Importantly, the thunder itself is not thought to be the main trigger. It is the combination of atmospheric conditions and airborne allergens associated with storms that appears to be responsible.
Who is most at risk during thunderstorms?
The UKHSA says everyone can potentially be affected by thunderstorm asthma. However, some groups appear to have a higher risk.
1. People with asthma
People who already have asthma are among those most likely to experience worsening symptoms during a thunderstorm.
This includes people with both well-established and previously undiagnosed asthma.
People whose asthma is poorly controlled may be particularly vulnerable. If asthma symptoms are already difficult to manage, exposure to a sudden increase in airborne allergens may make breathing problems worse.
The UKHSA also notes that people who do not yet know they have asthma can experience symptoms during a thunderstorm-related episode.
2. People with hay fever
Hay fever, also known as seasonal allergic rhinitis, is another important risk factor.
Hay fever occurs when the immune system reacts to allergens such as pollen. During periods of high pollen levels, thunderstorms can potentially redistribute and fragment airborne pollen, increasing the amount of tiny particles that can reach the lower airways.
People with hay fever who do not normally experience significant breathing problems should still pay attention to new symptoms such as wheezing, chest tightness or shortness of breath.
The UKHSA identifies people with seasonal allergic rhinitis as a group that may be more vulnerable to thunderstorm asthma.
3. People with asthma and hay fever
Having both asthma and hay fever can be particularly relevant because the two conditions involve sensitivity to airborne allergens.
Someone who already knows that pollen worsens their asthma should take extra care when high pollen levels coincide with thunderstorms.
Following an individual's usual asthma and allergy treatment plan is important, particularly during periods of high pollen.
4. People with undiagnosed asthma
Thunderstorm-related breathing problems can sometimes be the first indication that someone has asthma.
A person may not consider themselves to have a lung condition but could develop significant coughing, wheezing or difficulty breathing after exposure to storm-related airborne particles.
The UKHSA specifically includes people with asthma that has not yet been formally diagnosed among those who may be at greater risk.
5. Younger adults
Age may also play a role.
UKHSA guidance says previous thunderstorm asthma events suggest that young adults, particularly people under 30, may be more likely to be affected.
However, this does not mean older adults or children are protected. Thunderstorm asthma can potentially affect people across different age groups.
Can other lung conditions be affected?
Asthma is the condition most strongly associated with thunderstorm asthma.
There is also some evidence that other respiratory conditions may be affected by weather and airborne allergens, although the relationship with thunderstorms is less certain.
For example, Asthma + Lung UK has highlighted evidence suggesting that hospital admissions for chronic obstructive pulmonary disease (COPD) may increase following thunderstorms, although more research is needed to understand the reasons.
This means people living with long-term respiratory conditions should not automatically assume that thunderstorms are harmless simply because they do not have asthma.
If a particular type of weather regularly causes breathing problems, it is worth discussing this with a GP or respiratory healthcare professional.
Why can thunderstorms cause breathing problems?
The process can seem surprising because rain is often associated with clearing the air.
During a thunderstorm, however, strong air movements can change the distribution of pollen and fungal spores.
Pollen grains are relatively large particles. Under the right storm conditions, moisture can cause them to rupture into much smaller fragments.
These fragments can become airborne and potentially travel deeper into the respiratory system when inhaled.
The risk appears to be greater when thunderstorms occur after a period of warm and humid weather, particularly when pollen or fungal spore levels are already high.
UKHSA says environmental factors, including high levels of pollen or fungal spores, are associated with thunderstorm asthma events.
What should people do during a thunderstorm?
People who know that thunderstorms or pollen can worsen their asthma should take sensible precautions.
If possible, staying indoors before, during and shortly after a thunderstorm can reduce exposure to outdoor airborne allergens.
Keeping windows closed during the storm may also help limit the amount of outdoor particles entering the home.
People with asthma should continue taking their medication according to the treatment plan provided by their healthcare professional. Anyone prescribed an inhaler should make sure it is available when needed.
People with hay fever should also continue their usual treatment and follow advice from their healthcare professional.
If you need to go outside during a period of high pollen and storm activity, reducing exposure to airborne particles may be helpful, although there is no guarantee that this will prevent symptoms.
What are the warning signs to look for?
Symptoms that may indicate asthma or worsening asthma include:
- Coughing
- Wheezing
- Shortness of breath
- Chest tightness
- Difficulty breathing
- Needing a reliever inhaler more frequently than usual
A sudden change in breathing should not be ignored, particularly if symptoms are severe or rapidly getting worse.
The NHS advises people with asthma to seek medical advice if their treatment is not helping or if they need to use their inhaler more frequently than usual.
For urgent but non-life-threatening medical advice in England, NHS 111 can help assess symptoms and advise on the appropriate service.
If someone is experiencing a severe asthma attack and their usual treatment is not helping, emergency medical assistance should be sought.
Is thunderstorm asthma common?
Thunderstorm asthma is considered relatively uncommon, but UKHSA has documented episodes in England.
The phenomenon has been recognised since the 1980s, with the first recorded UK episode occurring in Birmingham in 1983.
UKHSA surveillance has also identified increases in asthma-related healthcare activity coinciding with thunderstorm conditions in more recent years.
During one episode in June 2021, emergency department attendances for asthma in affected areas increased substantially compared with expected levels.
However, not every thunderstorm produces a thunderstorm asthma event. Researchers are still working to understand why some storms are associated with sudden increases in breathing problems while others are not.
The full list of people who should take extra care
Based on current UKHSA guidance, the groups of particular interest are:
- People with diagnosed asthma
- People with poorly controlled asthma
- People with asthma who have not yet been diagnosed
- People with hay fever or seasonal allergic rhinitis
- People who have both asthma and hay fever
- Younger adults, particularly those under 30
The wider population should also be aware that thunderstorm asthma can potentially affect anyone.
Final thoughts
Thunderstorms are usually nothing more than a striking weather event, but the combination of storm conditions and airborne allergens can create problems for people with sensitive airways.
The greatest concern is for people with asthma and hay fever, particularly when pollen levels are high and the weather is warm, humid and stormy.
Knowing the warning signs and having an asthma management plan can make it easier to respond if symptoms suddenly worsen. If you notice a new or significant change in your breathing, do not assume it is simply the weather.
For people with asthma, keeping medication available, following their prescribed treatment and limiting exposure to outdoor allergens during storms can help reduce potential risks.
Sources
- UK Health Security Agency, GOV.UK: Thunderstorm asthma.
- UK Health Security Agency: Thunderstorm asthma and public health.
- UK Health Security Agency: Asthma and airborne allergens.
- UK Health Security Agency: Outdoor airborne allergens.
- UKHSA research: Asthma healthcare presentations during a June 2021 episode.
Medical disclaimer
This article is for general information only and is not a substitute for medical advice, diagnosis or treatment. Health risks can vary from person to person. If you have asthma, hay fever or another respiratory condition, follow the treatment plan provided by your healthcare professional. Seek urgent medical help if breathing problems are severe, rapidly worsening or your usual asthma treatment is not helping.