"HEART ATTACK RISK TRIPLES IN TRAFFIC"warns the headline.
The article cites a study published in the New England Journal of Medicine which says that the risk of heart attack appears to triple within an hour of being in traffic. Not only that, but the most likely culprit is air pollution.
Now I'm all for decreasing traffic congestion, but there are plenty of justifications for doing that, that don't involve misleading people. It would be nice for the sake of context to mention that air pollution has been decreasing dramatically, and will continue to do so.
Also, saying that something "triples" your risk of heart attack doesn't tell you how much you should worry about it unless you, again, have context. And here comes the context, way at the bottom of the article:
[Dr. Murray Mittleman, a cardiovascular disease epidemiologist at Harvard University] contends that the increased risk associated with traffic might be hard for most people to discern. Even though traffic might double or triple a person's risk of heart attack as compared with the "absolute" risk that person would face under normal conditions, "the absolute risk is probably quite small."
A 50-year-old man, for instance, might face a one-in-a-million chance of having a heart attack in any random hour, Mittleman said. So if his risk was tripled because of traffic exposure, he still would have only a three-in-a-million risk.
Of course, "Traffic Linked to 3-in-a-million Risk of Heart Attack" is not much of a headline.