The effects of both climate change and air pollution may be causing the increasing break-up and distribution of pollen micro-particles which can travel deeper into the lungs, triggering asthma attacks in susceptible people, a leading expert will tell delegates at the British Thoracic Society Winter Meeting today (Thursday 7th December 2017).    

Professor Isabella Annesi-Maesano, from National Institutes of Health (NIH) and the Pierre Louis Institute of Epidemiology and Public Health in Paris, will tell the audience of UK lung specialists that thunderstorms are often a major catalyst for this process and an increasing body of evidence now exists showing the occurrence of severe asthma epidemics during thunderstorms in the pollen season, in various geographical zones.

The speech will cover how:

  • air pollution and climate change are having a major impact on chemical and biological factors in the environment, including a lengthening of the pollen season and the physical breakdown of pollen
  • air pollution may be causing the external membrane of pollen to become more fragile and break, meaning allergens can leave more easily – and these smaller particles have the ability to travel deeper into the lower airways, causing asthma in those susceptible to pollen nasal allergy. In addition, air pollution itself induces airway inflammation and can add to the damaging effects of these sub particles
  • during a thunderstorm, dry uplifts of air can draw whole pollens into the high humidity at the cloud base where particles may rupture due to the electricity in the storm, and then cold downdrafts carry small pollen fragments to ground level where they are spread. Consequently, there is an unusually high level of allergens in the air at ground level

Professor Annesi-Maesano explains:

“The effects of climate change and pollution pose an increasing threat to our health – and our lungs are on the front line. 

As an example, increased severe wind storms are carrying pollen in great quantity and over long distances, while at the beginning of thunderstorms the outer membranes of the pollen disrupts, releasing tiny particles into the atmosphere, that contribute to ‘thunderstorm asthma’. This can be very dangerous for people with pollen nasal allergy that have never experienced asthma attacks and don’t know how to manage them.

During the first 20–30 minutes of a thunderstorm, people with pollen nasal allergies may inhale a high concentration of the pollen fragments dispersed into the atmosphere, which in turn by penetrating the airways, can induce asthmatic reactions, often severe.

People who are affected by pollen nasal allergy, but don’t have asthma, should also be alerted to the danger of being outdoors at the beginning of a thunderstorm in the pollen season, as such events can cause severe asthma attacks.

These risks are only likely to increase as climate change continues to cause further extreme weather changes.”

A large asthma outbreak was recorded in London in 1994 and coincided with a heavy thunderstorm. A large increase in the number of visits for asthma at the emergency departments of London and the southwest of England was observed. Many of the patients who experienced an asthma attack were not known to be asthmatics or known to be sensitised to pollen and had been affected only by seasonal rhinitis previously[i].

However, the largest and most severe episode ever recorded was in Australia in 2016.  Approximately 8,500 people sought hospital treatment on November 21 when there was a change to cooler temperatures and thunderstorms swept abruptly across Melbourne. Nine people died in just over a week following the event while other patients remained in critical condition in intensive care.

For more information prior to the British Thoracic Society Winter Meeting (that is, before Wednesday 6thDecember 2017), please contact:

Rosie Strachan: t: 020 7831 8778 or 07566 223644

Charlotte Sutton: t: 07958 279240

Ed Gyde t: 020 7831 8778 or 07809 574801            

During the British Thoracic Society meeting (from Wednesday 6th to Friday 8th December 2017):

Please contact the BTS news media office on t: 020 7798 4801/ 020 7798 4541 or the mobile numbers above.

Note to Editors:

The British Thoracic Society is the UK’s professional body of respiratory specialists. The Society seeks to improve standards of care for people who have respiratory diseases and to support and develop those who provide that care.  A registered charity, it has over 3,400 members including doctors, nurses, respiratory physiotherapists, scientists and other professionals with a respiratory interest. For more information, go to www.brit-thoracic.org.uk


The British Thoracic Society Winter Meeting takes place from Wednesday 6th to Friday 8th December 2017 at the Queen Elizabeth II Conference Centre in Westminster, London.


[i] Reference: Venables KM, Allitt U, Collier CG, et al. Thunderstorm-related asthma – the epidemic of 24/25 June 1994. Clinical and Experimental Allergy 1997; 27: 725–736.