Scientists claim they have identified the cleanest air on Earth over the Southern Ocean near Antarctica
The quest for pristine air on the planet seems to have finally paid off. Scientists from Colorado University claim that the Antarctic or the Southern Ocean, directly south of Australia, has the cleanest air on Earth. In a new study, scientists have detected an atmospheric region over the Southern Ocean that is free of human-induced pollutants or aerosols: tiny particles that escape into the air when fossil fuel is burned. These particles are capable of hitchhiking on wind currents and reaching distant lands.
"Overall, it suggests that the SO [Southern Ocean] is one of the very few places on Earth that has been minimally affected by anthropogenic activities," research scientist and co-author of the study Thomas Hill said in a statement. To arrive at these findings, the team studied bacteria floating in the air samples. "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," Hill added. These microorganisms, like aerosols, are carried by wind currents for thousands of kilometers to far-flung places.
The team studied the composition of microbes while aboard a research boat traveling south to the Antarctic ice edge from Tasmania, Australia. They wanted to trace the origins of the bacteria: whether it was a local inhabitant or a visitor from distant lands. After sequencing the bacteria, tracking the source, and studying wind back trajectories, they found that the bacterial origins were local, linked to the marine biological processes. "Antarctica appears to be isolated from southward dispersal of microorganisms and nutrient deposition from southern continents," Hill explained.
Based on their study on bacterial composition, the team noted that pollutants from human activities do not move southwards to the ocean. These findings stand in contrast with all other studies from oceans both in the northern hemisphere and subtropics, which found that most microbes came from upwind continents. Hill said that the air over the Southern Ocean was so clean that there was very little DNA to work with. "Jun and Kathryn [ two researchers involved in the study], at every stage, treated the samples as precious items, taking exceptional care and using the cleanest technique to prevent contamination from bacterial DNA in the lab and reagents," Hill said.
Though the Southern Ocean is pristine, it does not mean it is safe. The World Wide Fund for Nature (WWF) said the ocean has become a dumping ground for rubbish and is sensitive to climate change. Air pollution kills seven million people every year -- one-third of deaths from stroke, lung cancer, and heart disease, according to the World Health Organization (WHO). About nine out of ten people breathe polluted air. Recently, US researchers suggested that Covid-19 deaths were occurring in regions with higher pollution levels. “The evidence we have is pretty clear that people who have been living in places that are more polluted over time, that they are more likely to die from coronavirus,” Aaron Bernstein, the director of the Center for Climate, Health, and Global Environment at Harvard University, told BBC.
The study is published in Proceedings of the National Academy of Sciences.