If you rationalize a certain bad habit with the old excuse, “Hey, I’m HIV positive, so smoking’s the least of my worries,” you’d better revise your thinking—or quit. A new study by researchers at Ohio State University shows that smoking-induced emphysema is occurring at strikingly higher rates—and younger ages—in HIVers. Investigators followed people who smoked a pack a day for 12 years or more to see how many developed this potentially lethal condition, in which damaged bronchial tubes and lungs lead to shortness of breath. More than a third (37 percent) of puffing HIVers developed emphysema, while none of the HIV negative (matched for similar age, sex and smoking habits) did. And although emphysema tends to hit smokers in their 50s or 60s, the median age for the HIV positive was a shocking 33. The researchers bet that either HIV infection itself or the inflammation it causes accelerates the smoke-induced lung destruction. Why not circle the next National Smokeout Day (November 18) on your calendar?