Bad news for smoke inhalers on two fronts. Doctors in Scotland report marijuana smoking make not be as harmless as some advocates think. Researchers treated four men with emphysema. They could find no genetic susceptibility or explanation from the illness, except that all were reasonably heavy, long-term cannabis smokers.

According to the report from the journal Thorax:

• While tobacco cigarettes have filters that protect smokers to an extent from some of the noxious substances, marijuana smokers roll their own, thus forfeiting that barrier.

• Since people take bigger breaths while smoking marijuana and hold smoke in their lungs longer, they expose themselves to more substances.

As for tobacco smokers, another Thorax study reports a mother's smoking during pregnancy appears to reduce the baby's lung capacity. The reductions in air flow, researchers found, could have serious implications in later life, including bronchitis, emphysema, lung cancer and cardiovascular disease.

Source: Michelle Healy, "Marijuana Smoking Linked to Emphysema" and "Smoking's Effect on Baby," USA Today, March 21, 2000.