An eight-year-old girl, living near a major road in the Jiangsu Province of Eastern China, has become the youngest person in China, and possibly in the world, to be diagnosed with lung cancer caused by pollution—the cause of her disease according to Chinese officials. And last month, the World Health Organization classified air pollution as a major human carcinogen.

We talked with C. Arden Pope, economics professor at Brigham Young University in Provo, Utah. His research into the effects of air pollution on human health and mortality has been instrumental in establishing federal air quality regulations. He begins by saying that lung cancer in children, all but unheard of worldwide, lands in uncharted research territory.

What do we know about childhood lung cancer in China and around the world?

Nothing. I think we ought to be honest. I’m not familiar with any studies of that. In the American Cancer Society children aren’t even enrolled. I know of no lung cancer study that enrolls children. This is a very, very young lung cancer case. [Note: There have been younger children diagnosed with lung cancer linked to genetics, not pollution.]

Levels of PM2.5—microscopic particles filling the air as a result of pollution—have been shown in some industrialized areas of China to reach levels up to 40 times higher than the exposure level considered safe by the World Health Organization. What is PM2.5, why is it dangerous, and how can it lead to lung cancer?

There are lots of carcinogens emitted with industrial pollution. Our respiratory systems filter out the relatively large particles from air pollution. And they’re heavy enough to fall from the air quickly. PM2.5 is a measure of among the finest of the particles; fine enough to stay in the air for weeks. The particles are a fraction of the size of the width of a human hair. The tiny ones come nearly entirely from burning things—coal, gasoline, and diesel. Those tiny combustion particles are small enough to penetrate the lungs, and they’re made up of all sorts of nasty particles.

The U.S. Environmental Protection Agency’s standard is an annual average of 15 micrograms per cubic meter of air, though they allow for daily spikes of up to 35. How does air pollution in industrialized areas of China compare to pollution in some the “dirtiest” American cities?

We’re way better than that. Their annual average may be as much as 80 to 100 (micrograms per cubic meter of air) with Beijing sometimes peaking at 800 to 900. In the United States, a couple of decades ago in places like Pittsburgh and Los Angeles, we had places that averaged in the low 30s. The most we get now, even in our most polluted cities, is the low 20s.

You’ve researched epidemiology as well as the economics of pollution. What do we know about the economic impact of air pollution in China?

It’s very complicated. There’s no doubt that the industrial activity in China that is contributing to their economic well-being also contributes to poor health effects. The benefits [of industrialization] versus loss of health and productivity are trade-offs not fully understood. But we know from our experience in the U.S. that we get quite substantial benefits when we are able to reduce air pollution. The benefits of clean air are unbelievably high—at least two to three times the costs associated with reducing pollution.

Is there evidence of other ill health effects from air pollution?

Absolutely. Probably the strongest relationship with air pollution is cardiovascular disease; and the higher the air pollution, the greater the risk. [See related story: "Coal Burning Shortens Lives in China, New Study Shows."]

What were your thoughts when you heard of a young child with lung cancer?