Earlier this year, the U.S. Food and Drug Administration (FDA) ruled that electronic smoking devices (like vape pens and e-cigarettes) will be considered “tobacco products” and, as such, will not be available to consumers under 18 years of age. The regulation of sales were in effect starting Monday.

For retailers and customers, this means the purchase of e-cigarettes is no different than that of cigars and traditional cigarettes. Retailers are mandated to verify a consumer’s age using a valid photo ID, as per the Tobacco Control Act of 2009.

“This action is a milestone in consumer protection. Going forward, the FDA will be able to review new tobacco products not yet on the market, help prevent misleading claims by tobacco product manufacturers, evaluate the ingredients of tobacco products and how they are made, and communicate the potential risks of tobacco products,” said the FDA in an announcement.

The regulation will have an impact for young users, as the Centers for Disease Control and Prevent found that use amongst teens has tripled in a year. A recent study, published in Environmental Science & Technology, found that vapor from e-cigarettes contain 31 harmful chemicals. Two of those chemicals, acrolein and formaldehyde, are potential carcinogens.

In 2009, the FDA banned the sale of e-cigarettes after conducting a small-scale test to find they contain “detectable levels of known carcinogens and toxic chemicals to which users could potentially be exposed.” A year later, the ban was removed after a court ruled that the FDA had had no evidence of harm. With the new ruling, the FDA will require manufacturers to register with the agency and place warning labels on packages.

“This important final regulation puts several strong provisions in place that will serve to protect the public health and rein in an unscrupulous industry,” said Chris Hansen, president of the American Cancer Society Cancer Action Network, reports Fox6Now. “There are thousands of products on the market.”

The American Vaping Association, however, sees the regulation in a different light. In a statement, Gregory Conley, president of the association, said the regulation “marks the beginning of a two-year countdown to FDA prohibition of 99.9 percent of vapor products on the market.”