Hurricane Ophelia arrives in Ireland on Monday October 16. Source: NASA Worldview

The remnants of Hurricane Ophelia brought hurricane-force winds to the British Isles when the storm made landfall in Ireland on Monday, October 16. As the Met Office warned of a “potential danger to life,” three fatalities were reported across the country.

Those in the path of the storm experienced its full devastation. However, as Ophelia made its way across the Atlantic, the turning air mass also transported particulate matter from forest fires in Portugal as well as sand from the Sahara Desert.

This confluence of natural phenomena had an unprecedented air quality impact. It’s a shocking example of how unpredictable air pollution can be during extreme weather events—even for those out of the storm’s immediate path.

Much of the smoke and dust stayed high in the atmosphere, minimising health impacts for those on the ground. However, there were reports from across France and the UK of a grim, yellow sky bearing a red sun for the length of the transportation episode. Bit early for Halloween! 🎃

The plume of Saharan sand was visible on Plume Labs’ World Air Map on Monday October 16.

Sand and dust suspended in the air is part of the PM10 family of pollutants, meaning particulate matter with a diameter smaller than 10 microns. Also emitted by road vehicles, chronic exposure to PM10 can increase the risk of cardiovascular diseases as well as lung cancer.

Smaller particles can be even deadlier to human health. Named PM2.5, those with a diameter of less than 2.5 microns and can penetrate into the bloodstream through the lungs causing serious harm.

In this example, strong winds also transported PM2.5 pollution from fires burning across Portugal. These devastating wildfires, in which at least 30 people died, were exacerbated by Ophelia’s passage across the Atlantic.

Forest fires (in red) in Portugal on Sunday October 15 and smoke transportation on Monday October 16. Source: NASA Worldview

Natural disasters such as hurricanes and wildfires can be incredibly damaging in their own right, but pollutant transportation can also lead to far reaching air quality consequences.

Even if you are not directly affected by dangerous natural phenomena, it is important to keep track of air quality updates in your region to make sure you have all the information you need to reduce your exposure to air pollution and stay safe.