FIREWORKS RELEASE THE POLLUTANT OZONE. A CAUSE FOR CONCERN? 

The spectacular fireworks that mark public events like the Olympics and the new millenium, leave a nasty afterglow of the air pollutant ozone according to new research.

Ozone is best known in the stratosphere, where its formation into the "ozone layer" has a protective effect on the Earth by shielding it from ultraviolet radiation.

But in the lower atmosphere it is a respiratory irritant, a greenhouse gas and a plant toxin. Its production from oxygen gas in this part of the atmosphere had been thought to require sunlight or nitrogen oxides.

But now scientists have shown the ultraviolet light released by the burning of metal salts in fireworks can do the job too, resulting in surges in ozone when neither sunlight or nitrogen oxides are present.

The team from Jawaharlal Nehru University in India reached their conclusion after monitoring ozone levels during the annual Diwali celebrations in Delhi in October and November.

Their work, published in 28.06.01. of Nature, found that the ozone concentration in the air normally peaked in Delhi at around noon and fell to negligible levels by sunset.

But during the festival, when evening fireworks were lit, there was a surge in ozone from 8.40 pm that did not subside until 2.30 am the next morning, and was not linked with levels of nitrogen oxides in the air.

Further laboratory experiments showed the more the flammable materials in the fireworks were burned, the more ozone accumulated.

The authors say the process is similar to the way "good" ozone is generated by ultraviolet radiation in the stratosphere.

But the NSW Environment Protection Authority says because fireworks are infrequent, their overall contribution to air pollution is low.

"We're not active on fireworks because we think they are an insignificant source of pollution compared to all the other things out there," spokesman John Dengate told ABC Science Online.

Monitoring at 20 stations across the Sydney metropolitan area had failed to detect any difference in ozone after any of the recent major fireworks displays. The gas probably "blew away" or was degraded, Mr Dengate said. 

Source of the given news and the copyrights belong to a ABC Science Online.

Back