What pollen actually is
Pollen is how plants reproduce. Trees, grasses and weeds release microscopic grains into the wind in quantities that are hard to picture: a single ragweed plant can put out a billion of them in one season. Most drift a few hundred metres. Some travel hundreds of kilometres before they land.
For about one person in four, breathing them in triggers an immune response: itching eyes, a blocked nose, worsened asthma. The immune system misreads a harmless plant protein as a threat and reacts as though it were one.
Which is why the species matters more than the total. Each plant releases a different amount, at a different time of year, with different potency per grain. Birch arrives in tree-sized volumes and a few grains can set off a reaction. Grass comes in far smaller numbers and still affects more people than anything else. Averaging them into one “pollen count” throws away the only details you could act on.
Atmos tracks six species separately: Alder, Birch, Olive, Grass, Mugwort and Ragweed . Each is graded on its own scale, hour by hour, three days ahead.
In the air right now
CAMS European forecast · today's peakPick a city. These are real forecasts rather than examples, and the differences between them are the point.
The allergy year
Six species, staggered across the year. If your symptoms return at the same time every spring, the calendar usually names the culprit before any test does.
Outlined column is the current month. Seasons shift by a few weeks with latitude and with the year's weather.
Where this comes from
All pollen figures come from CAMS, the Copernicus Atmosphere Monitoring Service, via Open-Meteo. They are modelled forecasts rather than measurements from a trap on a roof, which is what makes hour-by-hour coverage possible everywhere at once.
Europe only. CAMS does not model pollen outside Europe, so Atmos shows no pollen elsewhere rather than showing a guess. Coverage beyond Europe is on the roadmap.
Thresholds follow EAACI and CAMS categories, and are the same numbers the app uses , so the site and the app cannot disagree: both read from one table.