Air quality in Belgium: where to check and what to do

Short answer. Check IRCEL-CELINE's current BelAQI index, used by Belgium's three regions since 1 August 2017 ¹². It runs from 1 (Excellent) to 10 (Horrible) and is tied to the WHO 2021 guidelines: from level 6 (Poor), the WHO daily guideline is exceeded ¹. On ozone smog days, IRCEL advises avoiding heavy outdoor effort between noon and 8 pm ⁴.

Where can I check air quality right now?

IRCEL-CELINE publishes the current BelAQI on its website ². The current index uses the most recent hourly concentrations, so a quick rise or fall in pollution shows up at once; the index for past days and the forecast use daily means ¹. IRCEL also says this hourly index is meant for the BelAIR app ¹.

When the air is exceptionally polluted, IRCEL publishes extra warnings naming the pollutant, the start and expected length and intensity of the episode, and the regions affected; you can subscribe to them by e-mail on its homepage ³.

What do the index levels mean?

BelAQI has 10 levels: Excellent, Very good, Good, Fairly good, Moderate, Poor, Very poor, Bad, Very bad and Horrible ¹. It covers PM10, PM2.5, ozone and nitrogen dioxide ¹. The index is at least 3 once the WHO annual guideline is exceeded, at least 6 (Poor) once the WHO daily guideline is exceeded, and 10 once WHO interim target 2 is exceeded ¹.

See Air quality index explained.

How polluted is the air on average?

The population-weighted median of Belgian cities shows about 10 µg/m³ of PM2.5 (annual mean 2021-2023) ⁶, twice the WHO guideline of 5 µg/m³ ⁸. Nitrogen dioxide is about 13.4 µg/m³ ⁷, above the WHO guideline of 10 µg/m³ ⁸. That NO2 figure is a regional background over roughly 80 km: a busy street will be higher.

What should I do on a bad air day, or with smoke or dust?

• Ozone smog: ozone peaks in the afternoon and early evening. IRCEL advises children and people with sensitive airways to avoid heavy physical activity outdoors between noon and 8 pm from 180 µg/m³, and everyone from 240 µg/m³ ⁴. Sensitive people are advised to stay indoors during an ozone episode, and rooms are best aired before noon or after 10 pm ⁴. If you have symptoms, see your family doctor ⁴. Belgium's ozone and heat plan runs a vigilance phase every year from 15 May to 30 September ⁵. See Ozone days.
• Fine particles: people with asthma, COPD or heart problems, the elderly and children are risk groups ⁴. During a particle peak, IRCEL advises vulnerable people to stay indoors with doors and windows closed and without airing, not to smoke, and to avoid sustained effort such as running; people with heart or lung disease should ask their doctor whether to adjust treatment ⁴. See Pollution episodes, Sensitive people and polluted air and Children and polluted air.
• Heavy smoke or a chemical leak: the authorities may ask you to shelter. Go into the nearest building, close all doors and windows, switch off ventilation, heating and air conditioning, and close the outside air supply of your chimney ⁹. Instructions come through BE-Alert, websites, social media, radio and TV ⁹; see our Belgium alerts page. See also Wildfire smoke, A clean-air room at home and Masks for smoke.
• Dust: see Dust storms.

A household plan can note who in your home is sensitive to polluted air and where to shelter.

Frequently asked questions

Is BelAQI the same as the European index?

No. BelAQI is Belgium's own 10-level index, rebuilt on the WHO 2021 guidelines ¹.

What ozone level triggers advice in Belgium?

180 µg/m³ for sensitive people and children; 240 µg/m³ for everyone ⁴.

How do I get smog warnings?

Subscribe by e-mail on IRCEL-CELINE's homepage ³.

How long does sheltering last?

From a few hours up to 24 hours at most; if things do not improve, you may have to evacuate ⁹.

Sources

1. IRCEL-CELINE (Belgian Interregional Environment Agency) — BelAQI – Information (new BelAQI, November 2022) — https://www.irceline.be/en/air-quality/measurements/belaqi-2022/info_nov2022 (accessed 2026-10-27)
2. IRCEL-CELINE (Belgian Interregional Environment Agency) — Current index — https://www.irceline.be/en/air-quality/measurements/belaqi-2022 (accessed 2026-10-27)
3. IRCEL-CELINE (Belgian Interregional Environment Agency) — Alerts — https://www.irceline.be/en/air-quality/alerts (accessed 2026-10-27)
4. IRCEL-CELINE (Belgian Interregional Environment Agency) — Frequently asked questions — https://www.irceline.be/en/documentation/faq (accessed 2026-10-27)
5. IRCEL-CELINE (Belgian Interregional Environment Agency) — What is the 'Ozone and heat plan' in Belgium and what are the different phases? — https://www.irceline.be/en/documentation/faq/what-is-the-ozone-and-heat-plan-in-belgium-and-what-are-the-different-phases (accessed 2026-10-27)
6. Atmospheric Composition Analysis Group (ACAG), Washington University in St. Louis — Surface PM2.5, V6.GL.02.04 (annual mean 2021-2023) — https://sites.wustl.edu/acag/datasets/surface-pm2-5/ (accessed 2026-10-27)
7. Copernicus Atmosphere Monitoring Service (CAMS) — CAMS global reanalysis (EAC4) — https://ads.atmosphere.copernicus.eu/ (accessed 2026-10-27)
8. World Health Organization (WHO) — WHO global air quality guidelines (2021) — https://www.who.int/publications/i/item/9789240034228 (accessed 2026-10-27)
9. Centre de crise National (NCCN), SPF Intérieur — Se mettre à l'abri — https://centredecrise.be/fr/que-pouvez-vous-faire/le-bon-reflexe/se-mettre-labri (accessed 2026-10-27)