SAharan’s dust high in the skies of Europe brought about spectacular sunsets in February. Many of us have found dust on our cars, and the snow in the Alps has become stained orange, but it has always been difficult to determine how much Saharan dust we breathe. For decades, we have been measuring the amount of polluting particles in the air, but not its composition. However, air observatories managed by universities in London, Birmingham and Manchester now perform real-time chemical analyzes. They showed that silicon, aluminum, calcium and iron particles in Saharan dust were the main particulate pollutants in all three cities on Saturday February 20 and that the dust was breathed in by Londoners for the next two days.

Saharan dust events are common in Mediterranean countries. It is also transported to the west by the trade winds of the Atlantic. Dust from North Africa fertilizes the Amazon, but it also causes air pollution problems in the Caribbean islands and the southern United States.

The dust of the desert is not like the sand of the builder; it contains many biological particles and allergens. A recent study in Miami found an increase in hospital visits for people with chronic obstructive pulmonary disease during Saharan dust episodes. Other studies have also revealed problems for asthmatics. In June 2020, Cuban authorities asked islanders to wear face masks and urged vulnerable people to stay indoors as a huge cloud of Saharan dust moved west. Warning systems are in place in Spain and Portugal, but more research is needed on the health impacts of desert dust.

Saharan dust can have a major effect on weather systems, suppressing the formation of hurricanes and, darkening the snow, advancing spring thaws in the Alps. It is not known if the events will increase in the future. A drier climate in North Africa can lead to an increase in airborne dust, but changes in weather conditions can reduce its spread. However, alpine ice cores spanning the past two millennia suggest that Saharan dust has increased over the past 100 years. The Saharan dust events between 1315 and 1365, a period that includes the Great Famine, in which about 10% of Europe’s population perished, and the Black Death, are also noteworthy in the ice core records. This has led to speculation that poor air quality due to Saharan dust may have contributed to a decline in human health and made the population more vulnerable.