Impact of atmospheric electrical charges on ryegrass pollen rupture and sub-pollen particle release.

Thunderstorm asthma (TA) is a significant health concern, recorded in 26 instances globally, primarily linked to ryegrass pollen. Existing research has shown that physical forces such as wind and rain can cause pollen to rupture during thunderstorms, creating micronic, inhalable allergen-rich fragments called sub-pollen particles (SPPs). However, little is known about the role of electrical charges in storm clouds, such as those associated with lightning, in triggering pollen rupture. This study presents the first simulation-based evidence that the static electric fields typical of storm clouds (105-870 kV/m) can fragment pollen into SPPs. The results reveal a clear increase in pollen fragmentation and dispersal when exposed to these charges - especially at higher electric field strengths and higher humidity. Under discharge conditions, such as simulated lightning (arcing), fragmentation intensifies, generating abundant, irregularly shaped ruptured pollen particles, as confirmed by scanning electron microscopy. The results identify both static and discharge electrical processes in storm clouds as drivers of pollen rupture, advancing the mechanistic understanding of TA. In the context of climate change-driven increases in severe storm frequency and intensity, this dual-mechanism insight has important implications for forecasting TA risk and mitigating respiratory health impacts.