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. Is Vaping Worse Than Smoking? The Hospital of Central Connecticut CT CDC Report Warns E Cigarettes Are Causing Smoking Rates To Increase In The U.S. Tobacco 21 Increased e cigarette use prevalence is associated with decreased smoking prevalence among US adults Harm Reduction Journal Springer Nature Link