Asthma and airborne allergens
Source: gov.uk (2025-08-06)

Asthma is a long-term condition and it is thought that symptoms can be worsened by exposure to viruses, allergens and air pollution.

CCHS navigation menu: CCHS homepage (https://www.gov.uk/government/organisations/the-centre-for-climate-health-security)Topic: environmental exposures (https://www.gov.uk/government/collections/environmental-exposures) Air-related exposure: airborne allergens (https://www.gov.uk/government/collections/airborne-allergens)Part of: The Health Risks of Airborne Allergens

Key resources for asthma and airborne allergens:

Asthma and Airborne Allergens

Asthma - NHS (https://www.nhs.uk/conditions/asthma/living-with/)

More content:
- Thunderstorm asthma (https://www.gov.uk/guidance/thunderstorm-asthma)
Bioaerosols and the respiratory system

Exposure to microbes, especially during early life, helps us to develop healthy immune systems. However, in sensitive people, exposure to bioaerosols (tiny, airborne parts of living things) causes breathing issues like coughing, wheezing, sneezing, shortness of breath, as well as other symptoms like stomach problems, tiredness and headache.

As we breathe, we inhale bioaerosols which can become trapped in different parts of the respiratory system depending on their size. The largest particles can become trapped in the nose and upper airways whilst smaller particles reach the lower airways and lungs. The largest particles over 10 micrometers in diameter include fungal spores and pollen and can deposit in the upper airway like the nose, throat and trachea.

Figure 1. The impact of inhaling bioaerosols on the upper and lower respiratory systems

A changing climate could mean seasonal changes to airborne allergens with greater and/or longer exposures, and people may experience symptoms that last longer and are more severe. Conditions like hay fever, asthma and eczema are also expected to become more common, which also increases the financial burden of airborne allergens (2 (#refs)).

Asthma and airborne allergens

Asthma is a long-term condition that has symptoms including coughing, wheezing, chest tightness and shortness of breath. The causes of allergies are yet to be determined. Although they can occur at any age, they are more common in children than adults and they can also run in families ​(1 (#refs)). Asthma is a very common in the UK, with 7.2 million people suffering from the condition (2 (#refs)). Cases of asthma and allergies have increased in recent decades and are becoming more widespread ​(3 (#refs))​.

About 10 to 20% of people are sensitive to pet fur, 6% to fungi, and 1 to 2% to dust mites, but these numbers rise to 20 to 70% in people with respiratory conditions (4 (#refs)). It is thought that certain things can make symptoms worse, like getting sick from a virus, being exposed to allergens and episodes of increased air pollution ​(5 (#refs))​. People with conditions like asthma are also more likely to experience symptoms from bioaerosols, which can be similar to asthma symptoms ​(4 (#refs))​.

Around 10 to 15% of homes have dampness, which can lead to fungal growth. Long-term exposure to fungi in damp environments can cause sensitisation, inflammation, and allergies ​(4 (#refs))​. If you have a sensitisation to mould and other airborne allergies, the likelihood that you may have severe asthma is far greater ​(6 (#refs)). Severe asthma is a form of asthma with symptoms that are harder to control even with higher medicine doses (7 (#refs)).​ In addition, the presence of damp and mould is linked to new cases of asthma and respiratory infections each year.

If you have asthma, there are several things you can do in order to help alleviate your symptoms, which are detailed on the NHS asthma page (https://www.nhs.uk/conditions/asthma/living-with/). In addition to these steps, you can identify and avoid your triggers and undergo regular check-ups. It’s worth knowing that cold weather is a common trigger for asthma symptoms, and you should make sure to take enough medication with you when going on holiday (8 (#refs)).

References

Allergy UK, ‘About Allergy’ (https://www.allergyuk.org/about-allergy/) (Viewed 25 March 2025)

Asthma and Lung UK, ‘What is asthma?’ (https://www.asthmaandlung.org.uk/conditions/asthma/what-asthma) (Viewed 25 March 2025)

Sedghy F, Varasteh AR, Sankian M, Moghadam M, ‘Interaction Between Air Pollutants and Pollen Grains: The Role on the Rising Trend in Allergy’ (https://pmc.ncbi.nlm.nih.gov/articles/PMC5941124/) Reports of Biochemistry and Molecular Biology 2018: Volume 6(2) pages 219 to 224 (Viewed 20 March 2025)

Goode EJ, Douglas P and Marczylo E, ‘Understanding the Public Health Implications of Bioaerosols’ (https://www.gov.uk/government/publications/chemical-hazards-and-poisons-report-issue-28) Chemical Hazards and Poisons Report 2022: issue 28 (viewed on 1 April 2025)

Public Health England, ‘Health Matters: Air Pollution’ (https://www.gov.uk/government/publications/health-matters-air-pollution/health-matters-air-pollution) 2018 (Viewed on 20 March 2025)

Zureik M and others, ‘Sensitisation to airborne moulds and severity of asthma: cross sectional study from European Community respiratory health survey’ (https://pubmed.ncbi.nlm.nih.gov/12193354/) British Medical Journal 2002: Volume 325 pages 411 to 414 (Viewed on 11 April 2025)

Asthma and Lung UK, ‘What is severe asthma?’ (https://www.asthmaandlung.org.uk/conditions/severe-asthma/what-severe-asthma) (Viewed 25 March 2025)