Smoking inside a vehicle is more dangerous to health than previously thought, health experts said on Thursday.

Smoking inside vehicles makes the air 10 times more toxic than the federal government says is hazardous for breathing, said Kimberly Belshe, secretary of the California Health and Human Services Agency.

She was making the remarks in downtown Los Angeles while launching a campaign to ban smoking inside cars.

The city of Los Angeles enacted a newly enacted state law unveiled on Thursday, which bans drivers from lighting up in the presence of children.

"Our efforts to address the dangers of secondhand smoke in California began over a decade ago," said Belshe.

"Today, our state continues to be a leader by ensuring that children and youth traveling in cars are not exposed to secondhand smoke," she said.

Under the "Smoke-free Cars with Minors" law, a violation is punishable by a 100-dollar fine.

Children who are exposed to secondhand smoke have a greater risk of asthma attacks, ear infections, bronchitis and pneumonia, according to state health officials.

Long-term exposure has been linked to heart disease and lung cancer in adults.

"Infants and children are especially susceptible to the harmful effects of secondhand smoke," said Mark Horton, director of the California Department of Public Health.

"Smoking in a car, or any confined space, increases the level of pollution inhaled by children and adults, thereby increasing the likelihood of suffering from the negative health effects of secondhand smoke."

In 1994, smoking was banned in California workplaces. Four years later, smoking was banned in bars.

(Xinhua News Agency January 4, 2008)