Across the globe, thunderstorm associated asthma epidemics have been documented by a peak in hospital admissions for respiratory symptoms where there is both a high level of airborne pollens and thunderstorm activity.
Grass pollens, dust and other allergens are blown ahead of the storm-front by the outflow of air, as seen in the photograph below of a typical storm front.
Moisture in the air causes the airborne pollen granules to swell under osmotic pressure and then to rupture into particles small enough to be breathed deep into the smaller airways within the lungs. Here, they can irritate the lining to cause inflammation, smooth muscle contraction in the airway wall and mucus production all of which obstructs airflow, producing an asthma attack.
Whilst thunderstorm associated asthma epidemics have been reported in both metropolitan and rural areas, the greatest problem is where the grass pollen levels are high which covers much of rural NSW. In the Riverina, rye grass has been identified as the major culprit associated with the thunderstorm asthma season from September through to November.
High pollen counts during the spring thunderstorm season are not the only trigger for asthma, but these conditions can trigger a severe response. Unfortunately, the onset of symptoms can be quite rapid, making the prompt administration of a reliever medication important.
Microscope image of grass pollens. (http://www.ndt-educational.org/images/artefatti28.jpg)