Vaping has become common, but it's important to know what you're inhaling. Many e cigarettes contain nicotine, heavy metals like nickel and lead, and chemicals that can harm your lungs and overall health. Electronic cigarettes: A safe substitute? New Scientist Which e cigarette is most like my favourite cigarette? : The Electric Tobacconist Ltd. E Cigarette Vapor Linked to Lung Cancer in Mice Respiratory Therapy New warning labels for e cigarettes