So, are passengers getting bigger or airplane seats getting smaller? According to one U.S. lawmaker, it’s definitely the seats.

Rep. Steve Cohen, D-Tennessee, has proposed mandatory federal minimum size standards for airline passenger seats, reports CNN. Cohen claims that seat width “has shrunk from 18 inches in the 1970s to about 16.5 inches today.” He also says that seat pitch has shrunk from 35 inches during the 70s to about 31 inches today.

He does have a point – narrower seats and seat pitches have allowed airlines to cram more seats onto planes, which of course lead to higher profit margins. Add to this the fact that American bodies have grown considerably bigger over the years and you’ve got one hell of a tight fit.

CNN reports that in 1962, the U.S. government measured the width of American backsides in the seated position. Men’s backsides averaged an average 14 inches while women averaged 14.4 inches. Fast forward to a 2002 Air Force study, which found that male and female backsides grew to an average of over 15 inches.

Putting the comfort issue aside, Cohen insists his proposed bill is based on concerns over safety. He says that the Federal Aviation Administration (FAA) is putting passengers at risk because there hasn’t been adequate emergency evacuation testing of airline seating with rows set with pitch under 29 inches.

Not everyone is buying into it, however. Brett Snyder of the consumer airline blog CrankyFlier says that a minimum seat and pitch requirement “would effectively be pushing the cost of plane tickets out of reach for the most price-sensitive travellers.”

Airlines for America, the powerful Washington airline lobbying group, says the Department of Transportation’s Advisory Committee for Aviation Consumer Protection has decided to not make a recommendation on seat sizes. The DOT oversees the FAA.

Cohen plans to propose the legislation as an amendment to an FAA reauthorization bill today. He’s also introduced it as a separate bill.