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Tackling international air pollution |
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Dust over the Sea of Japan, 8 April 2006. |
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Pollution from Eastern China, 27 January 2006.
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It's one of the most significant environmental attacks in history and a case too tough for even the CSI team to solve. The culprits are responsible for the premature deaths of over
60 000 people in the US alone, they can flee thousands of kilometres in a matter of days, they're invisible and not even the forces of global warming can stop them. They're fine particles, but a scientist at the Australian Nuclear Science and Technology Organisation (ANSTO) is keeping them under constant surveillance.
Using high-tech science known as accelerator-based Ion Beam Analysis; ANSTO scientist Dr David Cohen has developed a way to establish a fingerprint of the tiny particles and determine where they came from and trace their shifty movements.
Atmospheric fine particles are those with a diameter smaller than 2.5 micrometres (a micrometre is one millionth of a metre) and are typically produced by combustion sources including man-made sources such as cars, industrial plants, mining and natural sources such as soil and sea spray. Another of their dastardly acts is to reduce visibility in cities across the world - a common alias for the particles is smog
By collecting air samples twice a week from locations across Australia and internationally, David can keep them under close watch and decipher what fine particles are polluting the air and trace their movements.
"Ion Beam Analysis is exceedingly powerful, very fast and very sensitive," said David. "We can do an analysis on 30 different elements in a matter of five minutes."
By using ion beams from the ANSTO accelerators, his work determines what elements are present in the air samples and their impact. For example if the results show sulphur is present, one source might be coal burning. Chlorine and sodium can be attributed to sea spray and aluminium and silicon to windblown soils.
So why do we need to know what elements are in the air and where they came from?
"There are several reasons to look at fine particles - they affect health, visibility, pollution across borders and climate change. They're incredibly important," David explained. "If we can determine their source, the relevant parties can use that information to try to monitor, manage or limit those emissions."
However, it's possible that fine particles have just been given a bad wrap.
The tiny masses actually reflect the sun's energy in a phenomenon known as a negative forcing effect - at a rate of around 2 watts per metre. So the more fine particles in the air (either natural or man-made pollution), the more they counteract the effects of greenhouse gas warming.
If it wasn't for fine particles, David estimates temperatures would be 3-5 degrees Celsius higher, in line with the earlier greenhouse model predictions.
But don't go cheering for air pollution just yet. It's also fatal. Black carbon, or sooty, particles that are emitted from cars and industry and are some of the strongest heat deflectors, but they're also the most deadly.
With man-made fine particles having such a huge impact on health, climate and the visual appearance of cities, it's important to learn to control them, but like a three year old who's drunk too much red cordial, it's almost impossible. Fine particles are like the Lamborghinis of the atmosphere. David's work found that in the space of five days, atmospheric fine particles that originated in Mongolia's Gobi desert could travel through China, to North Korea and into the Philippines. "These particles can move from one side of Australia to the other in a few days," Cohen said.
The implication of this research is that air pollution and emissions that occur in one country don't just affect that area - it affects all the surrounding countries.
"It's hard for one country to clean up another country's mess. Burning forests in Sumatra affects the visibility in Singapore. Important international decisions need to be based on sound science,'' David said.
Atmospheric fine particles might continue to wage war on our visibility, our health and our climate, but science such as David's means we'll continue to learn where and what they're up to.
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According to the United States Environmental Protection Authority (USEPA), fine particles have been scientifically linked to serious health problems such as aggravated asthma, chronic bronchitis and shortness of breath |
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Scientific studies link respiratory-related hospital admissions, work and school absences and premature death to levels of fine particles in the air. So it's crucial that these atmospheric rebels are continually monitored and tracked. |
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