US transportation officials announced Wednesday that vaping on commercial flights is officially banned, just as is smoking the old-fashioned way.

The US Department of Transportation's decision to officially ban the use of electronic cigarettes on flights going to and from the United States ends any confusion as to whether vaping in the air is lawful.

"This final rule is important because it protects airline passengers from unwanted exposure to aerosol fumes that occur when electronic cigarettes are used onboard airplanes,” Transportation Secretary Anthony Foxx said. "The Department took a practical approach to eliminate any confusion between tobacco cigarettes and e-cigarettes by applying the same restrictions to both."

Congress banned airline smoking in 2000, and no US-based carrier has allowed even electronic cigarette use. Transportation officials, however, said that its previous rules could be construed to allow vaping.

In a statement, the Department of Transportation said:

The Department views its current regulatory smoking ban to be sufficiently broad to include the use of electronic cigarettes; however, the prior rule did not explicitly define "smoking." The Department took this action to eliminate any confusion over whether its ban includes electronic cigarettes.

The agency added that the airline industry should not be able "to adopt its own standards with respect to the inclusion of electronic cigarettes within the prohibition on smoking."

What's more, the agency said that "studies have shown that e-cigarette aerosol can contain a number of harmful chemicals" and that a "precautionary approach is best."

"The Department is particularly concerned that vulnerable populations (such as children, the elderly, and passengers with respiratory issues) would be exposed to the aerosol within a confined space, without the opportunity to avoid the chemicals," the agency said in a statement.