The Station Fire still raging in Northern Los Angeles has caused serious pollution in the city, prompting health officials to call for caution.

The South Coast Air Quality Management District (AQMD), the region's pollution-monitoring agency, urged area residents on Friday to take steps to protect themselves from the potentially cancer-causing smoke and fine particles generated by the wildfire.

In a statement, the AQMD urged everyone "to exercise caution and avoid unnecessary outdoor activities in any area directly impacted by smoke. This includes areas where residents can see or smell smoke."

The agency said air quality would reach unhealthy levels, including Friday, in the San Gabriel Mountains and San Gabriel Valley and areas affected by the Station Fire and other smaller fires in Southern California.

Meanwhile, Dr. Zab Mosenifar, medical director of the Women's Guild Lung Institute at Cedars-Sinai Medical Center, said the foul air creates particularly hazardous conditions for pets, children, the elderly and people with chronic respiratory problems resulting from such conditions as emphysema, asthma, congestive heart failure and chronic obstructive pulmonary disease.

Fine particulates, which are about 1/20th the width of a single strand or hair, can travel hundreds of miles and take days to disappear, he said.

"These particles continue to float in the air for 10 days to two weeks after the fires have been completely extinguished, so plan to stay indoors as much as possible until that time," he said.

Mosenifar said about 20 percent of the average population -- those without known respiratory problems -- have "hyper-reactive airways" and will show serious short-term effects in reaction to fire-generated smoke and small particles.

He said the smoke and particulates are as harmful to animals as to humans.

"In fact, animals, especially dogs, can have an even stronger reaction to smoky air than humans," Mosenifar said, adding that pets should be brought indoors until the smoke danger has passed.

Also on Friday, BREATHE LA, a nonprofit organization that promotes clean air, reported that lingering wildfire smoke " contains small amounts of cancer-causing chemicals similar to those found in cigarette smoke. Like second-hand smoke, exposure to wildfire smoke can be harmful even days after the fires have been extinguished."

The nonprofit organization said in a statement that the particles produced by the fires "are respiratory irritants, and exposure to high concentrations of particulate matter can cause persistent cough, phlegm,wheezing and difficulty breathing."

"The effects of wildfire smoke range from eye and respiratory tract irritation to more serious disorders, including reduced lung function,bronchitis, exacerbation of asthma and premature death," it said.

(Xinhua News Agency September 5, 2009)