Fair or not, doctors serve as role models for public health. If your doctor chain-smoked, for instance, it would be a lot harder for him or her to convince you that cigarettes were harmful. Then again, it stands to reason that the chances of finding a doctor who lights a new cigarette with an old one should be quite low, since he or she presumably knows the dangers of the practice far better than the average person.
This last point is the basic idea behind a recent study of smog avoidance conducted by urban planners Eric Morris and Michael Smart of UCLA. Since doctors are experts in the field of health, and since urban pollution is bad for a person's health, Morris and Smart reasoned that doctors might take more precautions than the average person to distance themselves from its cloudy path.
The question has some very practical implications. Smog has been linked to an increased chance of respiratory illnesses like pneumonia and bronchitis, and even to permanent lung damage. (As we recently pointed out, it also may have an impact on cognitive development.) If doctors take more precautions against exposure to urban smog than lay people do, that could mean the public fails to understand the true dangers of pollution, and that better public-health outreach is necessary.
To test this question, the researchers gathered Census data on roughly 250,000 people living in the Los Angeles area in 1980, 1990, and 2000, as well as information on pollution (measured in ozone levels) during these periods. They separated the residents into two groups: physicians and lay people. Then they compared where the groups lived and how far they commuted to determine if the presence of smog influenced either the housing choices or transportation behavior of physicians.
Well you might say the lab results came back negative. In the January issue of Transportation Research Part D: Transport and Environment, Morris and Smart report "no evidence that doctors are more or less more willing than comparable lay residents to trade off time or money to live in cleaner-air neighborhoods."
The researchers failed to connect lower levels of smog with areas inhabited by doctors in 1980 and 1990. They failed to find evidence that doctors were willing to bear higher home payments to avoid pollution, or that physicians moved to formerly "smoggy" areas that had improved air control over time. The researchers also failed to support the possibility that doctors were willing to live farther from work, and endure a longer commute, just to reside in a neighborhood with cleaner air.
While some of the results were mixed, the entirety of the data offered "no strong evidence" that physicians try to avoid city smog more than lay people, Morris and Smart conclude. That could mean your doctor doesn't know much more than you do about the health effects of smog:
Possible explanations for our results include that, broadly speaking, physicians and the lay public have similar levels of knowledge, and this is why they exhibit similar levels of ozone avoidance, or that there is a floor effect at very little willingness to avoid ozone for both our general and expert populations.
Before you go lighting up in front of your doctor, several caveats to the research should be noted. First there are the natural difficulties of pinpointing precisely why a person lives in a particular place. That point aside, Morris and Smart also presume that all physicians — regardless of specialty — understand the dangers of smog more than the average person because they routinely read top journals. While many doctors do check the likes of JAMA, Science, and the New England Journal of Medicine on the regular, most physicians, by necessity, dedicate most of their reading time to the specialty journals of their particular field. So while respiratory physicians in Los Angeles no doubt know the dangers of smog more than the average Angelino, podiatrists might not.
Beyond that, it seems strange that Morris and Smart located only 2,500 physicians out of the 250,000 area residents whose data they surveyed during the 30-year period. Is only 1 person in 100 a doctor in the Los Angeles area? That number would surely rise if the researchers included people who aren't doctors, but play one on TV.
Photo by Fred Prouser/Reuters.