The Natural Way
In the mid '80s, a group of us at UCLA were faced with a problem which had major impact on the longevity of people with poor or non-existent immune systems. You see, many of these folks were coming down with a very difficult to treat pneumonia, which those of us with good immune systems would rarely find troublesome.
A half dozen of us from different fields such as pharmacy, radiopharmacy, nuclear medicine, respiratory medicine, computer sciences and internal medicine came up with a contraption made out of plumber's clamps, tubing, a weather balloon, an oxygen supply, an aerosolizer and even a lead-lined garbage can!
We needed to scientifically measure how the lungs work and how best to give a therapeutic dose of inhaled medicine to prevent pneumocystis pneumonia. We were in uncharted water. Even knowing what was "normal" was unknown. So, we evaluated our contraption in the "dry" lab before trying it on volunteer people. It worked better than we could have imagined.
In medicine, serendipity often plays a big, though unexpected, role. While figuring out what "normal" was, we accidentally found out the dramatic effect of cigarette smoking on the lung bed where the transfer of gasses occurs. Smokers had higher abnormal measurements than did very sick, immune-compromised, pneumonia patients! Smoking other herbs elevated the measures, but not as much as tobacco from cigarettes.
The good news for cigarette smokers is, the lung bed reversed to normal levels usually within a three day period as long as the patient stopped and stayed stopped from smoking. Though we didn't study the effect of secondary smoke on non-smokers, we believed the pattern would be about the same.
This doesn't mean that stopping smoking for three days will keep you from having big problems down the road, after all, there is cumulative damage to lung structure over time. But we proved lung gas transfer function improved in only three days, and presumably overall health improvement would follow.
If you can't or won't stop smoking, at least shift over to natural tobacco or a pipe, and be like Bill Clinton -- don't inhale.