Less harmful than commercial cigarettes.
Commercial cigarettes contain hundreds of harmful chemicals
including 40+ known carcinogens. The e-liquid that become
vaporized in an electronic cigarette contain far less
chemicals, and are often harmless. A typical e-liquid
solution would contain propylene glycol or vegetable
glycerin that usually make up about 85% of the solution.
The rest 15% of the solution would be nicotine, dozens of
flavoring ingredients, and water.