2 posts tagged with "Air quality"

Dust causes headaches through three distinct routes — allergic reaction to dust mite protein, direct irritation of the nasal and trigeminal system, and inflammation from fine particulate matter small enough to enter the bloodstream — and they need different responses. Working out which one is driving your symptoms is the difference between buying an air purifier that helps and buying one that sits in the corner making noise.

The word "dust" covers an enormous range of material, and that is a large part of why the topic is so muddled. Household dust is mostly skin cells, textile fibres, soil tracked in from outside, and — critically — dust mite faecal particles. Outdoor dust is soil, road wear, construction material and, in some regions, desert mineral dust carried thousands of kilometres. Combustion particles from traffic and wood smoke are something else again. These are not interchangeable.

Thunderstorm asthma happens because a storm's outflow concentrates pollen at ground level and moisture ruptures the grains into fragments small enough to reach the lower airways — particles that would normally be filtered out by the nose instead go straight into the bronchi. A whole pollen grain is roughly 20 to 40 microns across and gets trapped in the upper airway. The starch granules released when it bursts are 0.6 to 2.5 microns, which is small enough to be inhaled deep into the lung. That size change is the entire story.

The effect can be dramatic. In Melbourne in November 2016, a single thunderstorm during grass pollen season produced thousands of emergency presentations within hours and overwhelmed the city's ambulance service. It is the most severe documented event of its kind, and it made a phenomenon that had been described in scattered case reports into a recognised public health hazard.