Audio Transcript:

LISA MULLINS: Detroit's troubles may be reverberating around the world, but the auto industry isn't on the skids everywhere. In fact, it may be doing too well in some places. For example, in Tehran, more and more Iranians are buying more and more cars with predictable results ? congestion and smog. Steve Zind reports that the pollution there is causing health problems for citizens and headaches for city officials.

STEVE ZIND: Long lines of cars are a familiar sight in Tehran: crowding the streets, jamming intersections and circling endlessly in search of parking. Many of the drivers are also keeping an eye out for police ticketing cars without emission inspection stickers. It's an effort to get older, more polluting cars off Tehran's streets. At one inspection station, men loiter and chat outside their cars while they wait for the slow line to move. They all agree that Tehran has a serious air pollution problem. On some days, the government issues warnings about the pollution.

MAN 1: They alerted people, especially children, not to go out.

MAN 2: My uncle came from Orange County in the US on one of those days, when they said ?Don't go out in the streets?, and he said he felt dizzy.

MAN 3: This inversion happens every year. It doesn't bother me, but it does affect people with heart problems.

ZIND: Ringed by mountains, Tehran is vulnerable to wintertime atmospheric inversions, when cold air above traps pollution in the city. On the worst days, the city is sitting in a bowl of smog soup. That's when hospitals see a spike in the number of patients with complications from asthma and allergies, and more serious health issues. Doctor Majid Mokhtari runs a pulmonary and critical care services at a Tehran hospital. He says official figures show that thousands of residents die annually from pollution-related illnesses.

MOKHTARI: We know that the number of heart attacks increases during this season. We know that the number of strokes increases during this season. Other horrible things can happen with pregnancy: premature birth, growth retardation.

ZIND: Many locals wear surgical face masks or stay indoors to keep from breathing pollutants. But Mokhtari says that doesn't help.

MOKHTARI: We are all trapped.

ZIND: Tehran's air pollution is a chronic problem that the Iranian government has long struggled with. A decade ago lead was removed from gasoline. Iran's auto manufacturers were also required to meet emission standards, and programs were introduced to get older, polluting cars off the road. Massoumeh Ebtekar is a former Vice President who helped implement the changes, and she says they made a difference for a while.

EBTEKAR: We had a reduction in the amount of particulate matter in Tehran air. But then, after 2006 we witnessed an increase in the number of days that we have unhealthy air quality in Tehran.

ZIND: Ebtekar is a well-known figure in Iranian politics who now serves on the Tehran City Council. She says the gains of the government's anti-pollution efforts were more than offset by a huge growth in the number of cars in the city. So, Ebtekar says, Tehran is now trying other approaches to cut pollution, including a major expansion of the city's subway system. The goal is to carry 25 percent of the city's commuters a decade from now. Tehran has also instituted a permit system to limit the number of cars in the most congested areas. But Ebtekar says President Mahmoud Ahmadinejad's government hasn't followed through on other initiatives to reduce pollution ? like increasing the production of cleaner natural gas, so more cars can use it instead of gasoline.

EBTEKAR: So that was a major reason why now today we feel that we're moving backwards again.

ZIND: Ahmadinejad's government says that it has begun requiring the manufacture of cars that run on both fuels. It hopes to have a third of the country's vehicles burning natural gas in five years. But officials admit that the infrastructure to support those changes isn't there yet. Meanwhile, perhaps the biggest contributor to automobile pollution in Tehran remains unchanged. Iran heavily subsidizes the price of gasoline ? Iranians pay roughly 40 cents a gallon ? so there's little incentive not to drive. President Ahmadinejad had proposed reducing fuel subsidies in his latest budget, but the plan was recently shot down in Parliament. At the hospital where he sees the health toll auto exhaust is taking, Dr. Mokhtari says the lack of progress is discouraging.

MOKHTARI: It shouldn't take one more minute of delay. It is an urgent issue.

ZIND: For The World, I'm Steve Zind, Tehran.