Frequently asked questions

To automatically display the forecast for the city nearest to you. Your position is not recorded. If you decline, you can search for a city by hand.

The site covers major European cities (pollution, concentrations and pollen) and many cities worldwide, such as New York, Cape Town or Tokyo, for the pollution forecast (AQI) only: detailed concentrations and pollen are not available outside Europe. If no covered city lies within 100 km, a message tells you so and you can pick a city from the list.

AQI stands for “Air Quality Index”. From 0 to 50 the air is good; above 100 sensitive people may be affected; above 150 everyone may experience effects.

Concentration is the amount of a pollutant in the air (in µg/m³). The AQI converts it into a simple 0–500 index showing the level of risk.

The main pollutant for the period is shown with its maximum concentration. The concentration curves detail fine particles (PM2.5) and ozone.

They are model estimates: more reliable in the short term and for general trends than for a specific street. Errors grow with lead time.

The curve shows you. In general, ozone peaks in the afternoon in hot, sunny weather; fine particles rise in the morning and evening (traffic, heating), especially in winter.

Pollen is forecast in grains per cubic metre of air for five highly allergenic species (Grass, Ragweed, Adler, Mugwort, Birch). Values below 0.25 grain/m³ are shown as zero. A pollen is flagged “to watch” during its pollen season, and an alert is added when its threshold is exceeded, especially if an ozone pollution risk is forecast.

Use the “Share” button under the curve: it sends a link (with the place name) to your social networks, by message or by email.

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