Shrinking legroom on flights and narrower airline seats have prompted complaints by squeezed travelers all over. But what can be done about it, besides paying for an upgrade?

U.S. Rep. Steve Cohen, D-Tenn., has introduced a bill in Congress aimed at setting minimum seat sizes for airline passengers.

"Shrinking seat sizes isn't just a matter of comfort but safety and healthy as well," Cohen said in a written statement. He pointed to issues such as emergency evacuations and deep vein thrombosis.

Cohen is calling his bill the SEAT Act, for "Seat Egress in Air Travel."

It's an issue that has gained the attention of consumer groups and even the U.S. Department of Transportation's Advisory Committee for Aviation Consumer Protection.

Airlines, for their part, say they don't think there is an increased safety risk and that adding more seats to planes allows them to offer lower fares.

Delta has added seats to planes to boost margins, using so-called "slimline" seats and altering galleys used for food service.

"We can put significantly more seats on the airplane without jeopardizing seat comfort or legroom," said Delta chief financial officer Paul Jacobson said when discussing the topic with investors.