Dust that swept Europe in February affects weather systems but also contains many allergens. Dust turned the sky yellow over Lyon, France, in February. https://www.theguardian.com/environment/2021/mar/12/pollutionwatch-how-much-sahara-desert-dust-do-we-breathe Saharan dust high in the skies over Europe caused some spectacular sunsets in February. Many of us found dust on our cars, and Alpine snow has read more Pollutionwatch: How Much Sahara Desert Dust do we Breathe? (The Guardian)