A cooler northerly wind brought fresher temperatures last night and today, as some clouds came drifting in as well. This had a positive impact on the ozone peak, with ozone levels dropping to lower levels. At 3PM, the European alert level of 180 microgrammes per square cubic metre had not been exceeded anywhere in Belgium, as the above picture from Irceline.be shows.
However, the interregional unit for the environment (Ircel) warns that harmful ozone levels will be climbing again tomorrow and possibly also on Tuesday. Yesterday, the situation was worst in the south-east of the country.
Elevated ozone levels are triggered by a combination of air pollution, hot weather and sunshine. Older people, children and pregnant women are advised to avoid heavy physical exercise. When the European alert threshold has been exceeded, this advice applies to everyone, including well-trained sportsmen.