On every airline flight, a crew member talks to passengers in the exit rows to see whether they can, as Federal Aviation Administration regulations specify, “pass expeditiously through the emergency exit” if needed.

Given how passengers have grown in inverse proportion to the spaciousness of airliner seats, anything like “expeditious” evacuation of an entire airliner seems doubtful.

The typical economy seat is 17 inches wide, about an 8 percent decrease from the 18.5 inches of a decade or so ago, according to Paul Hudson, president of FlyersRights.org, a consumer advocacy group. The average American man is now 195.7 pounds, the Centers for Disease Control and Prevention says, about an 8 percent increase over the past 20 years.

Since most airlines charge $25 for checking a bag — oops, American, Delta, United and JetBlue just raised it to $30 — those heftier passengers are also lugging a lot more stuff onboard, along with comfort dogs, cats and cockatoos. It’s a zoo up there.

Under such constraints, can today’s jets be evacuated in the 90 seconds mandated by the FAA? Not according to passenger advocacy groups like Flyers Rights, which has repeatedly and unsuccessfully petitioned the FAA to use its rule-making authority to stop airlines from shrinking seats and passenger space. Not according to U.S. Reps. Peter DeFazio, D-Ore., and Rick Larsen, D-Wash., who have asked the Transportation Department’s inspector general to investigate FAA safety standards that haven’t been updated in decades.

Incredibly, it will require an act of Congress to ensure that the FAA does something, because the agency has denied that seat sizes and body mass index are factors in emergencies. The agency has even denied that it has the authority to regulate airliner seat size.

“The FAA has no evidence that a typical passenger, even a larger one, will take more than a couple of seconds to get out of his or her seat,” the agency told Flyers Rights in refusing that organization’s stop-the-shrink petition.

There’s no evidence of anything, though. Airliner makers consider evacuation drill footage to be proprietary, and the FAA agrees. Not that it matters. The industry now relies on computer simulations of emergency situations to model behavior. The Airbus A321 and some versions of Boeing’s popular 737 have never run live evacuation tests. The Boeing 757 was last tested in 1982.

That’s dangerous and potentially lethal. In the most recent real emergency evacuations, including one at Chicago O’Hare in 2016 that was clocked at 2 minutes 21 seconds, it’s apparent that passengers aren’t as quick-thinking as the jetmakers would have them. Some tried to retrieve their belongings from the overhead bins; others started shooting video with their cellphones — suboptimal behavior in an evacuation situation.

The evolution of “thin” seating, which requires less padding and framing, has allowed airlines to add even more seats. American’s new 737 Max jet has 172 seats compared with 150 for earlier 737s.

The carriers argue that the marketplace should decide minimum seat size, not the government, an argument that takes off from specious and lands at ludicrous. Four domestic carriers rule about 70 percent of the market. They are not moved by market forces, because they are the market. United, Southwest, Delta and American are more motivated by Wall Street, whose executives fly in private jets or in business class and don’t tolerate profit-trimming niceties.