A dust plume from the Sahara Desert will be arriving in North Carolina this weekend – look out for spectacular sunrises and sunsets! Our Air Quality team will be keeping an eye on their instruments, which should pick up some info on the concentration of “PM10” – dust-sized particles in the air. These particles can be inhaled and cause issues for people with asthma, allergies, or respiratory illnesses (including COVID-19), so please exercise caution and wear a mask or stay inside if you’re concerned. Fortunately, we’re expecting most of the dust to stay suspended high in the atmosphere, between 20,000 and 30,000 feet.

Dust plumes like this one originate in the Sahara Desert when massive thunderstorm complexes sweep vast quantities of dust into the upper atmosphere. Trade winds carry them west across the Atlantic and into the Caribbean, and from there they can circulate up into the southeastern US.

These dust plumes happen every year – on average, the Sahara produces 182 million tons of dust annually. A lot of it makes its way to South America, where it fertilizes the Amazon rainforest. But it’s unusual for a dust cloud this intense to impact the continental US.

Because we don’t deal with a lot of desert dust, EBCI’s air quality monitoring systems aren’t necessarily built for PM10. We’re usually more interested in PM2.5 – the even smaller airborne particles that are created by burning fuel (in a car engine, for instance) as well as chemical reactions in the atmosphere. These tiny particles are especially dangerous, easily making their way deep into the lungs and even the bloodstream. The good news is that PM2.5 has been declining for decades, as emission standards make everything from cars to factories cleaner and safer for the air we breathe.

Size of PM10 and PM2.5 relative to beach sand and human hair. Image from the EPA.

The other good news is that our PM2.5 monitors also pick up PM10 – the data isn’t quite Federal Equivalent Method (FEM) quality, but it should be more than good enough to see how much dust impacts our area over the coming week.

In the meantime, you may well be able to see its effects for yourself. Dust in the air scatters light, especially red light, making for vivid sunrises and sunsets. And the presence of the dust layer high in the atmosphere suppresses storm formation, stopping hurricanes in their tracks. It may even put a damper on thunderstorms in our mountains – we’ll have to wait and see!


 

If you want to check on air quality in Cherokee or follow the progress of the Sahara dust plume:

  • AirNow.gov is the place to go for daily Air Quality Index (AQI) updates and forecasts. AQI ranges from 0 to 300+. Values below 50 are considered good. Values over 300 are extremely hazardous.
  • PurpleAir is an online map of small air quality sensors, color coded by AQI. As the plume spreads, we expect to be able to see it on the map. (We don’t currently have any PurpleAir stations in Cherokee, but our Air Quality team is working to set one up at the old high school site.)
  • NOAA Satellites show real-time imagery of developing weather patterns, including the Sahara dust plume.

Thanks to Katie Tiger for her help putting this post together! Katie and Amy Smoker make up our Air Quality office here at EBCI Natural Resources.