The concentrations of fine particles have again exceeded the information thresholds in Brussels and Flanders. This has happened more often at the start of 2025 than in previous years.
The Interregional Environment Unit (Ircel/Celine) confirmed the concentrations of fine particles exceeded the information thresholds in Brussels and Flanders on Tuesday morning. No threshold has been exceeded in Wallonia for the moment.
"The information and awareness threshold of the ‘smog plan’ in the Brussels Region has been exceeded and as a result, the population is being informed about air quality," Brussels Environment spokesperson Pascale Hourman said. "This is the first of four phases of the contingency plan for pollution peaks."
The threshold value of 35 µg/m³ for PM2.5, averaged over the past 24 hours, was exceeded at around 9:00 in Brussels. In Flanders, the information threshold of 50 µg/m³ for PM10, also over the past 24 hours, was exceeded at 05:00 this morning, while the information threshold of 35 µg/m³ for PM2.5 was exceeded at 06:00.
This marks the fifth time this threshold has been surpassed this year. "This is more often than in the same period in previous years," Christophe Degrave, scientific collaborator at Ircel/Celine. "We find ourselves in a cycle of activation for different reasons."
At the start of the year, the threshold was surpassed due to fine particulate matter coming from Eastern Europe. At other points, this was the result of the formation of secondary particulate matter components and the meteorological situation (cold temperatures, lack of wind or sunny weather).
Why is pollution peaking?
The current meteorological situation – mainly the lack of wind – is unfavourable for the dispersion of air pollution. As a result, high concentrations of particulate matter are being measured in the air. These are mainly emitted by heating in buildings and car traffic.
Depending on how long people are exposed to these high concentrations and their health conditions, this could result in respiratory problems and an increase in respiratory diseases (such as bronchitis, asthma and lung cancer in the long term). Asthmatics or people with chronic respiratory problems may experience more frequent and more severe symptoms.
Vulnerable groups such as young children, the elderly and people suffering from lung or heart disease are particularly at risk. "We encourage these people to limit physical efforts, such as jogging," Degrave said.
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People are also asked to do their part to limit the emission of pollutants, including limiting car use (either by using other transport methods or working from home) and reducing energy consumption.
If this situation lasts for more than two days, measures will be taken to encourage alternatives to the car and to limit their use. The air quality is expected to improve from Wednesday. "However, the concentrations of particulate matter will increase again later in the week."
