​Thunderstorm asthma is associated with the occurrence of thunderstorms and high pollen levels. Thunderstorm asthma can be life threatening and can affect people who have never been diagnosed with asthma.

Last updated: 18 October 2022

What is thunderstorm asthma?

  • Thunderstorm asthma refers to episodes of asthma symptoms which occur when high pollen levels are combined with a
    thunderstorm.
  • It appears that thunderstorm asthma requires very specific weather conditions to occur as only rarely do thunderstorms that occur in times of high pollen levels have a health impact.
  • if the conditions necessary for thunderstorm asthma occur near a highly populated area it is possible for many people to be affected by thunderstorm asthma suddenly and simultaneously.
  • Thunderstorm asthma events have occurred in some areas of NSW such as the region surrounding Wagga Wagga. The Sydney Metropolitan Region has not been impacted by a significant thunderstorm asthma event.

What are the symptoms?

Symptoms associated with thunderstorm asthma include wheeze, chest tightness, difficulty breathing and cough. The symptoms can escalate very quickly and may become life threatening.

What causes thunderstorm asthma?

  • The cause of thunderstorm asthma is not fully understood.
  • Exposure to high concentrations of very small fragments of pollen appears to be an important part of the cause of thunderstorm asthma.
  • It is thought that moisture in the air during a thunderstorm swells pollen grains which burst, generating tiny fragments of pollen. Airflows in some thunderstorms concentrate these fragments in high numbers at ground level where they may be breathed in and affect people at risk of asthma symptoms.
  • In NSW, high levels of rye grass pollen appear to be associated with thunderstorm asthma in some areas.

Who is at risk?

People with asthma, people with undiagnosed asthma, people with hay fever (allergic rhinitis), and especially people who ‘wheeze and sneeze’ during spring.

When are people most at risk?

  • In NSW the period from October to November is a time of higher risk of thunderstorm asthma.
  • Being outside when pollen levels are high and thunderstorms are in the area is likely to increase the risk of an exposure that could lead to thunderstorm asthma.

How might you decrease your risk of having a thunderstorm asthma episode?

  • Since the environmental conditions associated with thunderstorm asthma are unpredictable, an important way of reducing your risk of having a severe thunderstorm asthma episode is by managing your asthma or hay fever throughout the year, especially during spring.
  • If you have asthma, use your preventer medication regularly as directed by your doctor, carry your asthma reliever (puffer) with you, and ensure that you have a current, personal Asthma Action Plan.
  • If you have not been diagnosed with asthma but wheeze and sneeze during spring, see your doctor to determine if you may have asthma and develop an action plan.
  • If you have hay fever you should see your doctor about medications you could use to manage your symptoms and discuss any possible symptoms of asthma you may have.
  • Stay alert to the symptoms of wheeze, chest tightness, difficulty breathing and cough.
  • Recognise the signs of an asthma attack or rapid escalation in symptoms such as:
    • difficulty breathing, laboured breathing making it difficult to speak in full sentences, or lips turning blue
    • asthma reliever medication providing little relief.
  • If an ambulance is called in an emergency that could be related to thunderstorm asthma, stay indoors with the person having the thunderstorm asthma episode while waiting for the ambulance.

Further information


Current as at: Tuesday 18 October 2022
Contact page owner: Environmental Health