A month after the federal Transportation Security Administration announced rules permitting only limited amounts of liquids on board airplanes, confusion over the new regulations has caused longer waits at security checkpoints.

At Hartsfield-Jackson Atlanta International Airport — the world's busiest in terms of passengers — average wait times have increased by five minutes at checkpoints; similar delays have jumped by seven minutes at O'Hare International Airport in Chicago, according to the TSA.

While that might not sound long, TSA officials are concerned those delays will significantly increase come the peak holiday travel season later this month.

"We're very worried about Thanksgiving. We know it's the busiest time of the year," TSA spokesman Christopher White said. "We know there will be a lot of infrequent travelers, so we're doing everything we can to get the word out."

The restrictions — which initially banned all liquids on board flights — were imposed in August after British police broke up a terrorist plot to assemble and detonate bombs aboard as many as 10 flights from Britain to the United States. They were subsequently eased to allow limited quantities of liquids, toiletries and other items.

Ahead of the holidays, the TSA is educating travelers with a campaign that includes posters at 425 U.S. airports detailing the rules, and additional TSA staffers to tell passengers in line at the security checkpoints about what is allowed.

The program is named the "3-1-1 on Air Travel," reflecting the 3-ounce bottle size limit, the fact that all liquids must fit in one quart-sized see-through bag and that there is a limit of one bag per passenger.

"We know we can allow this quantity of liquids without it being a threat to the aircraft. It's more sustainable than a total ban," White said. "We need to teach people before they get to the airport."

Screeners in Atlanta routinely search every other piece of carry-on luggage for liquids because some passengers have failed to declare them, which has led to the increased checkpoint delays, White said. Before the TSA restricted liquids on flights, the airport's screeners only checked about one bag in 10.

Some passengers have tried to take water bottles larger than 3 ounces through checkpoints. Others forget to have a quart-size bag for their liquids or have bags larger than the TSA standard. Such problems lead to longer lines as TSA officials must then search those passengers' carry-on luggage for other possible violations, White said.

At Atlanta, security wait times jumped from 18-1/2 minutes in September to 23-1/2 minutes in October. Average waits during peak hours at O'Hare increased from about 14 minutes in September to more than 21 minutes in October. At Dallas-Fort Worth International Airport and McCarran International Airport in Las Vegas, the waits grew by a minute. At Denver International Airport, the average time increased by 3 1/2 minutes.