Washington ? Airlines say they’re prepared for an onslaught of Thanksgiving travelers who may not know that big bottles of shampoo, mouthwash and hairspray are banned from carry-on luggage.

New restrictions on liquids, gels and aerosols in carry-on bags have caused longer security lines at major airports such as Hartsfield-Jackson Atlanta International Airport and Chicago’s O’Hare International Airport.

With 25 million passengers expected during the 12-day Thanksgiving travel period, airlines are gearing up for travelers unfamiliar with the rules.

“We’re ready to go,” James May, president of the Air Transport Assn., said Thursday. “We know we’ve got 25 million people coming.”

The Transportation Security Administration now only allows liquids, gels and aerosols in 3-ounce containers or less. They must be contained in one quart-sized zip-top clear plastic bag. Passengers must take the bag out of their carry-on luggage at security checkpoints.

The rules were put in place in September, after British police broke up a terrorist plot to blow up as many as 10 trans-Atlantic flights using liquid explosives.

To accommodate the Thanksgiving crush, the TSA is opening security checkpoints earlier and fully staffing them.

Most of the major airports are handing out free baggies, and volunteers, docents and interns will be on hand to help travelers, said Greg Principato, president of the Airports Council International.

An average of 2 million people a day will fly during the Thanksgiving travel season, which runs from today to Nov. 28. The two busiest days will be Nov. 26 and Nov. 27, May said.