WHO: Fumes from Diesel Exhaust Cause Cancer

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Lisa Mullins: I am Lisa Mullins and this is The World, a co-production of the BBC World Service, PRI and WGBH in Boston. It may seem obvious that breathing black smoke belched from diesel vehicles is bad for you, but the World Health Organization has ratcheted up its assessment of just how bad. The WHO had long considered diesel fumes a probable cause of cancer. Well, a new assessment concludes that the fumes definitely do cause cancer putting diesel exhaust in the same category as asbestos. Here is Christopher Portier who headed the WHO's re-assessment.

Christopher Portier: Diesel exhaust exposures are carcinogenic to humans — a group 1 carcinogen, the highest level you can possibly have.

Mullins: Health experts hope this stark announcement will prod governments around the world to clean up diesel exhaust. Our health and science editor David Baron is here to explain what is so carcinogenic in diesel fuel. What makes it bad for you David?

David Baron: Well, the bad stuff in diesel and all of those tiny particles of soot that come out and they lodge in your lungs. They're bad for many reasons not just cancer, but they of course can exacerbate breathing problems, asthma for instance. They also can exacerbate cardiovascular disease, heart disease. A number of studies over the years have shown that breathing those tiny particulars of soot increases the overall risk of death.

Mullins: Apparently, it's not the amount of diesel that you're exposed to; it's the kind of diesel and what it's made up of.

Baron: Well, that's right. In fact, here in the United States we've had an ongoing push to clean up diesel fuel and diesel engines. The issue in diesel fuel is the sulfur content and in the United States we have dramatically reduced the amount of sulfur in our fuel and that, by itself, has cleaned up the exhaust quite a bit. On top of that, when you use low-sulfur fuel you can use new, much cleaner diesel engines and when you use the new engines with the new fuel, the emissions are reduced by well over 90 percent. Everyone agrees that, you again using the latest fuel, the latest technology in the United States, the risk goes way, way down.

Mullins: Okay, so it's gone down here in the United States; it's gone down in Canada because the cleaner diesel fuel is being used. Where isn't it being used?

Baron: Right, the way I see it, this WHO announcement has a much, much bigger impact than what's going on in the developing world than in the developed world. If you look at a map of where in the world you can get low-sulfur fuel (and we're going to put a link to this at theworld.org), you'll see that in the U.S., in Europe, in Australia, in Japan we're using this low-sulfur fuel. But, if you look at Sub-Saharan Africa, China, Latin America, they're using the much dirtier diesel fuel which is bad not only in and of itself but it means they can't even use the new type of diesel engines. So, if we're ever going to clean up diesel in most of the world, we first need to get to the low-sulfur fuel.

Mullins: Okay, so the fuel has to be cleaner and then the buses and trucks have to be replaced and newer so they can use the cleaner fuel. What's getting in the way of that happening — bringing the standards of many parts of the world right now to that of, say, the U.S. and Canada?

Baron: Well, very simply, it's money. Taking the sulfur out of fuel is costly. It means rebuilding refineries and spending that extra money. In a lot of countries in the world, the petroleum companies are state-owned, so you're talking about the government, in essence, regulating itself. So, there is, understandably, a reluctance to spend the money to clean up the diesel fuel. The big hope among environmentalists and health experts is that this WHO announcement which carries a lot of weight, particularly in the developing world, that this could be an extra push for countries to make that investment in the cleaner fuels and then the cleaner diesel engines as well.

Mullins: David Baron, The World's health and science editor, thank you very much.

Baron: You're welcome.