History

PM₁₀

Evolution of the number of monitoring stations where PM10 is measured, including both the telemetric stations and the stations used in specific studies. The number of PM₁₀ monitoring stations in Belgium has risen from 20 in 1997 to 76 in 2020. Because the number of monitoring stations was considerably smaller in the first years, the uncertainty on the interpolated annual mean concentrations is greater in those initial years.

PM_2.5

Evolution of the number of monitoring stations where PM_2.5 is measured, including both the telemetric stations and the stations used in the specific studies. The number of PM_2.5 monitoring stations has risen significantly from 5 in 2000 to 74 in 2020. Because the number of monitoring stations was substantially lower in the first years, the uncertainty on the annual mean values is greater in these initial years. This is especially true for Wallonia where PM_2.5 was not measured before 2008.

Ozone

Evolution of the number of monitoring stations where ozone is measured, including both the telemetric stations and the stations used in specific studies. The number of ozone monitoring stations has risen from 12 in 1990 to 42 in 2020. Since the number of monitoring stations in 1997 is substantially lower than in 2015, the uncertainty on the interpolated annual mean concentrations is larger in those initial years.

Nitrogen Dioxide

Evolution of the number of monitoring stations where NO₂is measured, including both the telemetric stations, stations used in specific studies and stations that are managed by the electricity producers and the Belgian Petroleum Federation in cooperation with the regional environmental administrations. The number of ozone monitoring stations has risen from 12 in 1990 to 94 in 2020 and did not evolve since then. Since the number of monitoring stations in the first years was substantially lower than more recently, the uncertainty on the interpolated annual mean concentrations is larger in those initial years.

Sulfur Dioxide

Evolution of the number of monitoring stations where SO₂ is measured, including both the telemetric stations, stations used in specific studies and stations that are managed by the electricity producers and the Belgian Petroleum Federation in cooperation with the regional environmental administrations. The number of SO₂ monitoring stations has dropped from 81 in 1990 to 30 in 2020. In the years with fewer monitoring stations, the interpolated values have a larger uncertainty.