16 August 1999

Don't breathe easy!

by Kate Melville

The smoke that continues to cloud much of Asia may be far more damaging than medical officials admit. Up until recently children were seen as being at the main group at risk because they breathe 50 percent more air per kilo of body weight than adults. Now new research from the University of Delaware suggests that these tiny airborne particles may do more damage than previously assumed even to 'healthy' adults.

This is because the tiny particles can fly through human lungs up to two times faster and penetrate far deeper than previously assumed. Air pollution expert Professor Anthony Wexler, the studies author says quite simply, "Smog kills"!

The report published in the Journal of Aerosol Science, shows how a pollutant particle smaller than 2.5 micrometers penetrate both buildings and people's airways. Individually, these particles are so minute, they can't be seen without a microscope! Particle clusters produce clouds of dust, black soot and gray haze and, when ground-level ozone mixes with air pollution, choking smog can blanket cities, reducing visibility by up to 75 percent.

Clearly, whenever levels of fine pollutant particles rise in major cities such as New York and Singapore and London, an increased number of people die or enter hospitals. But, exactly how do fine particles impair breathing capacity? "As people breathe," Professor Wexler explains, "a clump of fine particles called a bolus will rapidly disperse throughout the lungs. At the terminal alveoli-little sacks at the end of each respiratory branch, where oxygen and carbon dioxide trade places with blood-these particles take up water and expand, much like a sponge, because of hydroscopic effects."

They might look stupid but next time there is a pollution warning get one of those kiiky white maks or even better a proper rubber respirator!