Smoking traditional tobacco-packed cigarettes has been banned on most U.S. commercial flights since the late 1980s. But the “No Smoking” signs didn’t specifically prohibit the latest nicotine-delivery device, e-cigarettes.

That oversight has now been remedied, with the imposition of a new DOT rule explicitly banning inflight vaping.

Under this rule, the use of e-cigarettes in all forms—including, but not limited to electronic cigars, pipes, and devices designed to look like everyday products such as pens—is explicitly banned.

The ban protects airline passengers from unwanted exposure to e-cigarette aerosol when electronic cigarettes are used onboard airplanes. Studies have shown that e-cigarette aerosol can contain a number of harmful chemicals.

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The new rule also extends the smoking ban, on both traditional and electronic cigarettes, to “all charter (nonscheduled) flights of U.S. airlines and foreign airlines where a flight attendant is a required crewmember.”

There’s not much relief for would-be smokers hoping for a nicotine hit before or after their flights, either. According to the American Nonsmokers’ Rights Foundation, e-cigarettes are already explicitly banned at 23 of the 35 largest U.S. airports.

After 20 years working in the travel industry, and almost that long writing about it, Tim Winship knows a thing or two about travel. Follow him on Twitter @twinship.

This article first appeared on SmarterTravel.com, where Tim Winship is Editor-at-Large.