Scientists identify cleanest air on Earth

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Scientists identify cleanest air on Earth

The Southern Ocean. Image via Spartan & the green egg.

 

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Researchers have identified Earth’s cleanest air – free of particles caused by our human activity – in a region in the Southern

 

Ocean off the coast of Antartica.

 

Weather and climate are complex processes that connect each part of the world to every other region. A team of climate

 

scientists from Colorado State University were curious to see just how far particles produced by human industry and activity

 

reach. To find out, they sailed from Tasmania into the Southern Ocean – which encircles Antarctica below 40 degrees south

 

latitude – and measured the bioaerosol composition – the particles in the atmosphere – at several points.

 

Location of the Southern Ocean. Image via Encyclopaedia Britannica.

 

They took measurements from the boundary layer, a part of the lower atmosphere that comes in direct contact with the

 

ocean’s surface and reaches as high as 1.2 miles (1.9 km) into the atmosphere.

 

The study, published June 1, 2020, in the peer-reviewed journal Proceedings of the National Academy of Sciences, found the

 

boundary layer air that feeds the lower clouds over the Southern Ocean to be pristine, free from particles, called aerosols,

 

connected to human pollution or other activity or transported from distant lands.

 

Aerosol filter samplers probe the air over the Southern Ocean on the Australian Marine National Facility’s R/V Investigator

 

The researchers said that it’s difficult to find any area or process on Earth untouched by people. The scientists suspected the

 

air directly over the remote Southern Ocean that encircles Antarctica would be least affected by humans and dust from

 

continents. They set out to discover what was in the air and where it came from. Colorado State University research scientist

 

Thomas Hill is a study co-author. Hill said in a statement:

 

    We were able to use the bacteria in the air over the Southern Ocean as a diagnostic tool to infer key properties of the

 

lower atmosphere. For example, that the aerosols controlling the properties of Southern Ocean clouds are strongly linked to

 

ocean biological processes, and that Antarctica appears to be isolated from southward dispersal of microorganisms and

 

nutrient deposition from southern continents. Overall, it suggests that the Southern Ocean is one of very few places on

 

Earth that has been minimally affected by anthropogenic activities.

 

These results counter other studies from oceans in the subtropics and Northern Hemisphere, which found that most

 

microbes came from upwind continents.

 

Bottom line: A new study suggests the cleanest air on Earth – free from pollution from human activities – is in a region of the

 

Southern Ocean which surrounds Antarctica.