Volcanic eruptions affect air quality in many ways. But how far away from the eruption is air quality affected? How far can volcanic ash and smoke travel?
Larger Volcanic Ash Typically Does Not Travel Very Far
During a volcanic eruption, the general rule of thumb is larger ash falls to the ground sooner than smaller pieces of ash.
In fact, most of ash larger than .01 mm falls to the ground within 30 minutes of eruption. But during powerful eruptions, larger pieces of volcanic rock (called pumice) have travelled over 6 kilometers from the eruption.
Smaller particulates of ash can travel much farther. These pieces of ash are typically less than 2.5 micrograms (PM2.5) in size. See below for some perspective on how small these particles really are.
How Far Can Tiny Dangerous Volcanic Ash Particles Travel?
These tiny particulates of ash (considered PM2.5) are of greatest concern to humans, as they are small enough to enter the blood stream and organs.
WATCH: 5 Things You Should Know about PM2.5 Air Pollution
Unlike the larger pieces of ash emitted from a volcano, these tiny particulates of ash can travel hundreds and even thousands of kilometers!
Exactly how far can depend on a lot of factors, including the strength of the eruption and wind conditions. But there are plenty of examples of volcanic smoke and PM2.5 spreading all the way around the globe.
As early as 1883, particulates from Indonesia’s Krakatau volcanic eruption were seen all the way on the other end of the world in New York.
How long did it take to get from Indonesia to New York? 13 days. In fact, volcanic ash from this eruption stayed in the atmosphere for years. The ash created vivid red sunset glows in areas of New York. These unusual sunsets even continued for three years!
How High Can Ash Get In the Atmosphere?
Volcanic ash emitted from a powerful volcano can get blasted 50 km into the earth’s stratosphere. Plumes (volcanic smoke) from Mt. St. Helens reached 31 km high into the atmosphere, while plumes from the Pinatubo eruption reached 45 km high.
Similar to the phenomenon that can occur with wildfires, plumes from volcanos can form pyrocumulonimbus clouds which can act as a “volcano in the sky”, blasting the volcanic plume to further heights into the stratosphere.
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