I turned 75 last month and In Jan., after going to a pulmonolgist and being told I had about a quarter of a lung left it got my attention. I knew I felt horrible, tired, short of breath, but concluded it was old age and cigs, just couldn't quit. In approx. Oct. 2012 I started smoking e-cigs due to feeling crummy and knowing the cigs were "killing" me. I would smoke maybe 3 to 5 real cigs a day while smoking the E's until the Dr. told me the facts. Left the Dr.'s ofc. and haven't had a real cig since. I use "Clean Cig" simple because I found them at a smoke shop on the counter and have not tried other brands. Truly all that stuff in a real cig is dreadful. I go crazy if I lose my fake cig, of course I keep a spare, hahaha - died in the wool addict. Oh, and started smoking at age 19. Tried to quit using the lasted mind bending drugs plus the gum and cold turkey one time for 3 months and nearly divorced my husband 'cause he made too much noise eating an apple, jk, ha
Good luck in any case.
Edit: My Dr. said the E cigs were fine!!