IRCEL: ‘Belgium’s air quality better, but still far from WHO’s advise values’

Belgium’s air quality in 2024 was comparable to that in 2023. Nitrogen dioxide and particulate matter concentrations decreased slightly, and there were fewer ozone days in 2024. In the long term, air quality has improved significantly. However, achieving the WHO health advice values ​​in all Belgian areas is still far out of reach.

According to the Interregional Cell for the Environment (IRCEL), wet and rainy weather was one explanation for the better air quality conditions. Fierens also refers to low-emission zones in cities and stricter emission standards specifically for car traffic.

Gradual downward trend

Like 2023, 2024 was a year with favorable weather conditions for air quality due to the wet summer and the absence of heat waves. The summer of 2024 was very wet, with significantly more precipitation than usual. At the beginning of summer, it was also a bit cooler and gloomier than normal.

From 2014 onward, we see a gradual downward trend that continues in 2024. The impact of the coronavirus crisis is visible in the kink in 2020. After the first coronavirus year of 2020, concentrations increased (temporarily) again in 2021 and 2022.

Nitrogen dioxide

Nitrogen dioxide is a typical traffic-related pollutant. In places with a lot of traffic, there is a direct link between NO2 concentrations and local (diesel) traffic. “Never have NO2 concentrations on urban background concentrations been as low as this year,” emphasizes Frans Fierens, spokesperson for IRCEL. There are a number of explanations for this:

• Nitrogen oxide (NOx) has fallen in all sectors and all EU countries.

• The number of diesel cars has fallen sharply; after all, diesel cars emit more nitrogen oxides than gasoline cars.

• Due to the introduction of low emission zones (LEZ) in several cities, the oldest and most polluting cars have been banned. A study by independent health insurance funds shows that the decline in NO2 concentrations is (slightly) greater in these cities.

Particulate matter

The European daily limit for particulate matter is 50 µg/m³ (daily average concentration). This limit may not be exceeded for more than 35 days. In 2024, the daily limit was not exceeded at any measuring location.

The favorable long-term trend is due to the declining emissions at the European level of both primary (or directly emitted) particulate matter and the substances (nitrogen oxides, ammonia, and sulfur dioxide) that form secondary particulate matter. The current European annual limit value for PM2.5 is 25 µg/m³. The new European directive provides for an annual limit of 10 µg/m³ in 2030.

Very strict values

WHO’s annual recommended value for PM2.5 is 5 µg/m³. This annual recommended value is only achieved in seven rural measuring stations in Wallonia (area below the Sambre and Meuse valleys) and in two urban measuring stations in the Walloon region (Namur and Liège).

The (very) strict WHO daily recommended value for PM2.5 of 15 µg/m³, which may be exceeded for a maximum of 3 to 4 days per year, is not yet achieved anywhere in the country.