IRA FLATOW: Now it’s time to play good thing, bad thing because every story has a flip side. Now we all know that exercise is good for you, right? You don’t necessarily have to run a marathon or spend hours in the gym. Even a good, brisk walk has benefits for the cardiovascular system.

But research published this month in The Lancet indicates that maybe not all walks are created equal. Joining me to talk about it is Jonathan Newman. He’s a cardiologist, assistant professor of medicine at New York University’s School of Medicine. Welcome to the program.

JONATHAN NEWMAN: Hi, thanks for having me.

IRA FLATOW: Now exercise is still good for you, right? No matter where you are.

JONATHAN NEWMAN: That’s right, Ira, and I think it’s tempting to extrapolate the results of this study in which the investigators did a really nice design and looked at some people over the age of 60 with either some chronic breathing problems or some people that had had previous heart trouble and some folks that were normal and had them walk in a highly trafficked area in London, Oxford Street, and then for comparison in Hyde Park– being in New York, the equivalent would be Central Park or Prospect Park in Brooklyn– and looked at a whole host of physiologic parameters. And they looked at vascular function, a noninvasive way we can look at what your arteries are doing and respond to a whole host of things, physical activity being one. And what they found, interestingly, was if you walk– and this is known.

With physical activity, there are some beneficial properties or beneficial effects on the function of your arteries. And those benefits were attenuated and in some cases reversed when walking in a high– an area of high traffic, high particulate air pollution, due to vehicular traffic largely. But the overwhelming evidence in other studies that have looked at this in particular is in balance, exercise even in areas, urban areas with high levels of air pollution or other pollutants, there is a benefit still to physical activity or exercise in that setting. It may be less and there may be other physiological characteristics, but this is not a reason to stop walking along busy streets, let’s say.

IRA FLATOW: Doing– is it the carbon– is that the carbon monoxide, is in the ozone, or is it the soot that seems to be–

JONATHAN NEWMAN: Right, so that’s a really interesting question. And the short answer is we don’t know exactly. There are– there’s been a lot of very important and interesting research from looking at what air pollution does on the population, level on the individual, and the source constituents, the individual things that make up air pollution, and which one of those things may be causing certain effects.

And it varies on the amount, you know, the temperature or the humidity can kind of exacerbate or ameliorate some of those effects. What I think is particularly interesting is that we know based on a whole host of data that air pollution and other environmental exposures in my particular area of interest have adverse cardiovascular effects, affect your heart and arteries and your body. And we don’t yet know exactly why.

There’s a lot of good work that has been done to try and understand that. And this is showing that, in fact, you can measure some of these effects on the moment to moment basis. And that may give us greater insight into what’s going on for heart disease risk in people at, let’s say, elevated risk of diabetes or who have other risk factors for heart disease. We may be able to understand more about heart disease itself based to our response to this stimulus.

IRA FLATOW: So you say your take home message is it’s better to walk than not walk. And if you’re contemplating where to walk, it’s better to go to the park instead of the city street.

JONATHAN NEWMAN: That is correct. I think that’s a reasonable summary, and I would say that there’s been some nice work, modeling studies, that have shown that there are very few places in the world and very few times in those places where the risk of limited physical activity outweighs the benefit of that activity. But it is some caution for people with multiple health conditions– lung disease, heart disease– that this may be a factor that may exacerbate some existing symptoms that they have.

IRA FLATOW: Thank you, Dr. Newman. Have a good weekend. Jonathan Newman, cardiologist, assistant professor of medicine at NYU School of Medicine.

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