A growing number of medical marijuana users are choosing to use vaping devices rather than smoking the drug, Reuters reports. Some people believe vaporized marijuana is safer. Several states, including New York and Minnesota, do not allow people to smoke medical marijuana.

Many new customers looking for devices for their medical marijuana are older nonsmokers who suffer from serious illness, vape shop owners and industry experts note.

A vape device heats cannabis leaves or concentrate to a temperature that is lower than required for combustion, according to the article. Vaping marijuana provides more privacy, because the vapor released by the device is almost odorless.

There are about 8,500 vape shops in the United States. Sales of e-cigarettes and supplies have reached $3.5 billion. According to the market research firm IBISWorld, sales of medical marijuana are expected to increase to $13.4 billion in 2020, from $3.6 billion this year.

Medical marijuana is legal in 23 states and the District of Columbia, according to the Marijuana Policy Project. An additional 15 states allow patients, often with severe seizure disorders, to use several strains of cannabis for medical reasons. Recreational use of marijuana is legal in Colorado, Washington, Oregon and Alaska.