Belgium experienced no ozone days in 2021, a first for more than 40 years
Belgium has not experienced any ozone day in 2021, a first since 1978, the Interregional Environment Unit (Celine) announced on Thursday during its provisional assessment. On the other hand, the annual average concentrations of fine particles increased again this year. Each year, this report analyzes the air quality on the basis of measurements of the concentrations of fine particles, nitrogen dioxide and ozone.
Regarding the concentration of nitrogen dioxide (NO2), a typical pollutant linked to road traffic, it seems to follow the same trend as in 2020 and remains below the measures of 2019, that is to say before the start of the pandemic. . Thus, the European annual limit value of NO2 will be respected for the second consecutive year.
According to the Interregional Environment Unit, the health restriction measures linked to the pandemic have had a positive impact on air pollution linked to traffic. “Further reductions in nitrogen oxides emissions from road traffic (due to the introduction of EURO6d, low emission zones) and possibly also favorable conditions have also had a positive effect“, adds Céline.”However, dissociate the impact of the health crisis, the reduction in NOx emissions or the impact of weather conditions that are difficult to achieve“.
The annual European values for fine particles were also observed at all the measurement sites. However, in the long term, the researchers observe that after falling in 2019 and 2020, the annual average concentrations have started to rise again this year. “The concentrations of fine particles are less affected by the mobility restriction measures put in place“, explains Céline.”Particulate matter has (many) more sources of emissions than just road traffic. Industry, domestic activity and agriculture are also important sources of fine particles“.
But 2021 will have been an exceptional year for ozone since, for the first time since 1978, no ozone days were recorded during the year. Ozone days are days when the European information threshold is exceeded for ozone is exceeded in at least one measurement site. “This is mainly due to the rainy summer and the absence of a heat wave.“, rejoices Céline.”Indeed, high concentrations of ozone are reached during hot and sunny summer days.“.