A new study published in Nicotine & Tobacco Research found that those using e cigarettes alone were more than twice as likely to develop COPD than people who didn't use any tobacco products, Public Health Burden of Secondhand Smoking: Case Reports of Lung Cancer and a Literature Review Juul nicotine hit may be 'worst for kids, best for smokers' WHYY Health Risks of Secondhand Smoke and Aerosols Factsheet US EPA