A study published in the journal of Regulatory Toxicology and Pharmacology has shown that harmful and potentially harmful constituents (HPCPs) are 1500 times lower in e-cigarettes than in conventional cigarettes. Little research has been done on e-cigarettes until now. The people scrunching up their faces and looking worried that a puff near them is going to kill them and the e-cig puffer can stop now. A biased and poorly done study done in 2010, published in an issue of Tobacco Control (of course) is discussed at http://health.universityofcalifornia.edu/2010/12/03/study-e-cigarettes-are-unsafe-pose-health-risks/. It’s now been proven that there is absolutely no detectable carbon monoxide inhaled from an e-cigarette. Regular cigarettes are 65% combustion byproducts, whereas there are no combustion byproducts during e-cigarette use. According to Dan Newlin, the nicotine yield in an e-cig is approximately 2%, much less than a regular cigarette. The main ingredients of an e-cigarette are consistent with the disclosed ingredients: glycerin and/or propylene glycol, water and nicotine. The control used in the study was ambient air, meaning the air in the room. This testing of various brands of e-cigarettes proves there is little or no detectable amounts of HPCPs. The levels of HPCPs were very much like the air blanks used as controls. It seems likely to me that the levels of HPCPs in the air are due to pollution. Pollution from cars, buses spewing black smoke everywhere and industrial waste should be the concern. These are the activities that impact health, not an e-cigarette.