What a Pollen Count Actually Means

I looked at pollen numbers for years without really knowing what I was reading. The app said high, I thought "right, high", and that was as far as it went. It turns out the number is both more useful and more limited than I had assumed.

What it's measuring

A pollen count is grains of pollen in a set volume of air, usually measured over 24 hours and given as grains per cubic metre. Most forecasts turn that into low, moderate, high or very high, because a number in the hundreds doesn't mean much to most of us on its own.

It isn't one thing

This is the part I wish I'd understood sooner. "Pollen" is really several different seasons stacked on top of each other:

• Tree pollen, usually earliest, late winter into spring
• Grass pollen, usually late spring into summer, and the most common hay fever trigger
• Weed pollen, usually later in summer and into autumn

So a high count in March and a high count in July are often completely different plants. If one bothers you and the other barely registers, a single overall number will keep looking confusing until you know which is which.

Why it doesn't always match how you feel

• Counts are usually taken at one station and averaged over a wide area. Your street can be different.
• It's a forecast. Rain, wind and heat all move pollen around after the number is published.
• What you did matters as much as what was in the air. A high count on a day you never went outside is not the same as a moderate count on a day you spent in a park.

That last one is why I stopped treating the number as the whole story and started noting what I actually did that day next to it.

Using it without overthinking it

You don't need the exact figure. High, medium or low, plus a note on whether you were out in it, is enough to spot a pattern over a few weeks. Precision you won't keep up is worse than a rough note you will.

This is general, practical information, not a diagnosis or treatment recommendation.

If you'd rather not do this on paper

This is exactly what I built SkinFam for, a private, on-device diary for eczema and skin flare-ups. It shows the day's pollen for your area next to your entries, so a run of high days is easy to see against how your skin and your sleep actually went, and nothing you log ever leaves your phone. Get SkinFam free on the App Store.