There is now evidence that passive smokers (people exposed to second-hand tobacco smoke) have vitamin C levels intermediate between smokers and non-smokers and also use up more vitamin C on a daily basis than do non-smokers. Several studies have shown that exposure of non-smokers to second-hand tobacco smoke (passive smoking) results in increased oxidative stress which in turn has been linked to an increased risk of heart and lung diseases. It is known that smokers have lower blood levels of vitamin C than do non- smokers and that smokers use up about twice as much vitamin C per day as do non-smokers. A recent experiment carried out by Finnish researchers found that exposing non-smokers to passive smoking for 30 minutes created considerable oxidative stress in their body and increased lipid peroxidation - a strong risk factor for coronary heart disease. A second experiment found that ingesting three grams of ascorbic acid prior to the exposure to smoke provided complete protection against the development of oxidative stress. Other researchers have found that vitamin C also protects against ozone-induced damage to the lungs. These finding underscore the need for an adequate vitamin C intake in order to reduce the risk of lung and heart diseases.
Jacob, Robert A. Passive smoking induces oxidant damage preventable by vitamin C. Nutrition Reviews, Vol. 58, August 2000, pp. 239-41