An extremely unusual haze of Saharan dust spread over Switzerland and southeast France on Saturday, leading to health warnings as a yellow hue tinged the sky.
The phenomenon first occurred on Friday, causing “a very clear worsening of sunlight and visibility,” MeteoSuisse weather service said. “Added to that is an increase in concentrations of fine particles.”
The dust is concentrated at lower than 3,000 meters (about 9,800 feet), and air quality was especially affected.
Switzerland’s aircheck monitoring application detected high levels of pollution in a corridor from southwest to the northeast.
Calculations estimate the amount of dust reached about 180,000 tons, double the levels registered in recent similar events, SRF Meteo forecaster Roman Brogli informed public radio.
Local authorities in the southeast and south of France said the air pollution threshold was breached on Saturday, with authorities in Herault department calling on residents to avoid intense physical effort, especially those with heart or respiratory trouble.
The Sahara Desert releases 60 to 200 million tons of mineral dust per year.
The largest particles quickly descend down to earth but the smallest can travel for thousands of kilometers.
The sand causes an orange tint to snow and can affect the melting processes, in particular for glaciers, reducing the ice’s ability to reflect sunlight.
The situation is forecasted to improve in France and Switzerland on Sunday.
