In 2018, there were 10 “days with ozone” in Belgium, that is, days with at least one point higher than the European threshold for ozone of 180 mg / m³. This is the highest number of days since 2010, according to the air quality provisional assessment of the inter-regional environment cell (Celine) released Wednesday. “Despite the exceptionally hot and unusually sunny summer, the number of days with ozone was low, compared with what could have been expected given the weather conditions,” the cell stresses, however. And the alert threshold was never reached during this year that is ending.
In 2018, days with ozone were observed in July and August. In July, there were two consecutive days on 3 and 4 July and four consecutive days from 24 to 27 July. In early August, there were three days with ozone from 2 to 4 August and a final day on 7 August. In 2017, there had only been five days, while during the 2003 and 2006 hot summers, 16 and 22 days above the information threshold were recorded respectively.
The other main air quality indicators show a positive trend in Belgium. The limit value of 40 mg / m³ of nitrogen dioxide (NO2) was only exceeded in two stations, against five in 2017. In Flanders, the limit value was exceeded near the Antwerp ring (Borgerhout), while in Brussels (annual average: 56 g / m³) at the Arts-Loi intersection. The decline in the number of days above the limit could be explained, according to Celine, by “the acceleration in the transition from diesel to gasoline and/or other types of vehicles”.
As for fine particles (PM10), the European daily limit value was respected throughout Belgium for the fifth consecutive year. “Despite weather conditions in 2018 often favorable to an increase in fine particle pollution (long dry periods with low precipitation), the number of days in 2018 above the daily limit remained comparable to previous years. The average annual concentrations of PM2.5 and PM10 also remained stable these past four years,” the cell says.