how many people in the us smoke cigarettes Chart: U.S. States That The Most Hidden Costs: The Economic Burden

Ten years ago, when you referred to cannabis, you were talking about dried plant material that people smoked, says Ryan Vandrey, associate professor of psychiatry and behavioral sciences at the Johns Hopkins School of Medicine

That said, filters will last for up to four years, so this helps reduce yearly maintenance costs

Smoke free goal 'a huge challenge' It has set an ambition for England to be smoke free - defined as less than 5% of the population smoking - by 2030

Some studies have found people who tried e-cigs wound up smoking fewer regular cigarettes, but they were no more likely to give up smoking entirely