The Belgian sky could turn orange this Wednesday due to Sahara dust

The Belgian sky could turn orange on Wednesday as a result of a large quantity of Saharan dust moving northwards across Europe over the next few days.

Aerosol forecasts from Copernicus, a component of the European Union’s space programme, predict the highest amount of desert dust in the air over western Europe between 15 and 17 March.

The Royal Meteorological Institute of Belgium says the dust cloud should reach Belgium on Wednesday evening. 

France has already seen amber skies after the dust crossed the Pyrenees and passed over the western part of the country before heading north. The phenomenon was particularly visible in Bordeaux or La Rochelle, according to Meteo France.

Copernicus forecasts also show degraded air quality across large parts of Spain and Portugal related to the Saharan dust transport.

“Forecasts since 11 March have been showing a large plume of dust with very high values of aerosol optical depth (AOD) and dust concentrations travelling northwards across the Iberian Peninsula, France and central regions of Europe,” the Copernicus Atmosphere Monitoring Service said in a statement. 

“The trajectory of this dust plume has resulted in very high predicted surface concentrations of PM10 up to 250 micrograms per cubic metre, although European Environment Agency measurements have been showing values in excess of this at many sites across Spain on 15 March.”

High concentrations of dust will impact air quality

The event isn’t unusual in its occurrence, but the extended duration and geographical extent are uncommon. The amount of dust in the air is greater than the EU recommended 24-hour mean threshold of 50 micrograms per cubic centimetre.

“Air quality is recognised as being vital to human health as high concentrations of dust can have health impacts on the respiratory systems of all people in the affected regions and add to particulate matter air pollution from local sources,” Copernicus warned.

Senior scientist Mark Parrington of the ECMWF Copernicus Atmosphere Monitoring Service said they’ll be monitoring the air pollution event. 

“Long-range transport events such as this occur most years and the impact of the current event is quite striking,” Parrington said. “While the dust will affect air quality in parts of southwest Europe, the larger scale impacts will be hazy skies or some surface deposition.”

The meteorological phenomenon of strong hot winds loaded with sand dust from the Sahara desert is called "calima" in Spain. It’s most frequent in the Canary Islands, located in northwest Africa.