Updated

Smoke from burning oil wells darkened the skies and made breathing uncomfortable in some parts of southern Iraq, but it probably poses no serious threat to the environment or to soldiers' health, experts said.

Oil smoke can cause temporary respiratory distress in young children or elderly people with medical conditions, said Richard Golob, an environmental consultant who specializes in oil pollution. But healthy soldiers should not suffer serious consequences.

Medical researchers have monitored Kuwaitis and American soldiers who were exposed to oil fires in the 1991 Gulf War, and 12 years later no increase in asthma, emphysema, or other lung diseases has been connected to them.

Iraqi troops retreating from Kuwait in 1991 ignited or damaged more than 700 oil wells. So far, only a handful such wells have been sabotaged in this war, all of them in southern Iraq.

"There looks to be only about 10 wells that we know of, out of possibly 1,000 in that area, that have been damaged," defense secretary Donald Rumsfeld said Friday.

Environmental damage should be minimal, according to experts.

"It certainly isn't pleasant," said Golob, chairman of World Information Systems in Cambridge, Mass. "But in terms of long-term environmental damage, we didn't see it during the Gulf War."

Oil spilled from the damaged wells could have more serious consequences than the smoke. In the desert, however, there are few lakes and rivers for the oil to flow into, so spills don't spread far.

The U.S. government has hired Houston-based oil services company Kellogg Brown & Root to put out well fires in Iraq. The company is a subsidiary of Halliburton Co., once headed by Vice President Dick Cheney.