Anything that can halt or reverse some of the damage of second hand smoke or smoking?

[Andrew]

To date, your assertion that "there is nothing demonstrated by double blinded placebo controlled trials to help reverse some of the damage from tobacco smoke exposure" is correct. There very well may be in a decade or two however as COPD is a growing problem worldwide and predicted to be the third leading cause of death globally by 2030. Not to mention all the other common lung diseases like IPF, CF, Alpha-1, etc. This is an area of very intense research at the moment. Quitting smoke exposure, along with exposure to other airborne pollutants, will reduce the rate of lung function decline however in those that have sufficient smoke exposure or for various other reasons have already developed COPD, even avoiding the initiating factor will not return the rate of decline to a normal pace as the disease is believed to be self perpetuating, sometimes refereed to as auto-inflammatory, once developed. Nothing will regain or regenerate lost lung function in chronic lung diseases as of the latest medical science today.

No vitamins or anti-oxidant supplementation has been shown to be effective in treating COPD as the defense mechanisms in smoker's lungs are dysfunctional due to increased DNA damage and cellular senescence. Some Supplementation, namely high doses of vitamin A, retinoids, were actually clinically proven to increase the susceptibility towards lung cancer in smokers and former smokers. These trials occurred in the late 90's.

Best thing to do is avoid all tobacco smoke and limit exposure to other forms of air pollution. And pay no attention to the pro-smoking wacko's i.e. piglet23.