Glutathione is highly concentrated in the epithelial lining fluid of the lungs. It helps protect against inhaled oxidants. Glutathione’s response to cigarette smoke was examined in mice. After cigarette exposure, the levels of GSH were depleted by almost 50%. Glutathione adapted to the smoke by increasing its levels within the epithelial lining fluid.

Irritation from components of particulates in smoke cause oxidative stress. Chronic smokers increase their defenses from the smoke by increasing their glutathione levels in the epithelial lining fluid. The epithelial cells (lung cells) become overwhelmed due to the repeated cigarette smoke which leads to cell toxicity. Repeated inhalation of cigarette smoke results in smoking-induced lung disease.

http://www.gshnow.com/smoke_article.html

http://www.ncbi.nlm.nih.gov/pubmed/21982222