(See: Flouris AD, et al. Acute impact of active and passive electronic cigarette smoking on serum cotinine and lung function. Inhalation Toxicology 2013; 25(2): 91-101.)
In the study, a sample of 15 smokers had their lung function measured before and after smoking, and before and after using an electronic cigarette. A sample of 15 nonsmokers had their lung function measured before and after exposure to secondhand smoke, and before and after exposure to secondhand vapor from electronic cigarettes.
The main study finding was as follows: "The assessment of lung function demonstrated that neither a brief session of active e-cigarette smoking nor a 1 hour passive e-cigarette smoking session significantly interfered with normal lung function. On the other hand, acute active and passive tobacco cigarette smoking undermined lung function, as repeatedly shown in previous studies."
The Rest of the Story
This is an important study because it demonstrates that neither active nor passive vaping is associated with any significant impairment of lung function, as measured by spirometry. While this does not rule out a long-term respiratory effect, it is the first step in demonstrating the respiratory safety of these products, as long-term damage from inhaled substances usually results from mechanisms that occur acutely. Certainly, for tobacco smoke, acute respiratory impairment can be readily demonstrated. That this is not the case with e-cigarette vapor helps support the notion that these products are not damaging to the respiratory tract and certainly supports the conclusion that vaping is much safer than smoking in terms of respiratory health impact.
Will the anti-smoking groups which oppose electronic cigarette use pay any attention to this study? I doubt it because they have apparently reached a pre-determined conclusion regarding these products and I don't think scientific evidence is of much concern to them.