How worried should New Yorkers be about falling window A/C units?

New York City is full of peculiar phenomena—rickety fire escapes; 100-year-old subway tunnels; air conditioners propped perilously into window frames—that can strike fear into the heart of even the toughest city denizen. But should they? Every month, writer Ashley Fetters will be exploring—and debunking—these New York-specific fears, letting you know what you should actually worry about, and what anxieties you can simply let slip away.

Eleven years ago, University of Virginia physics professor Louis Bloomfield debunked a popular New York City urban myth in his book How Everything Works: that if a penny were dropped from the top of the Empire State Building, the momentum it would gather on its long journey down meant that should it hit a pedestrian at the ground level in the head, the sheer force of it could kill them. In reality, “falling pennies flutter and experience so much air resistance that they max out at about 25 miles per hour,” Bloomfield explains. “A 25-mph penny doesn’t have enough momentum to hurt you.”

So when I asked Bloomfield about the other popular New York death-by-falling-object nightmare—the nagging fear or being killed or injured by an air conditioning unit falling from an apartment window, which, like clockwork, awakens in city dwellers every summer—I half expected him to laugh that one off as a physics myth, too.

But at approximately 41 pounds, the average window AC unit commonly found in New York’s older apartment buildings doesn’t need to fall very far or move very fast to achieve a potentially lethal amount of momentum were it to hit a human, Bloomfield told me: “At 25 mph it is seriously dangerous, and even a fall from the second or third floor will give it that speed.” Oh, good.

As far as New York anxieties go, the fear of the falling air conditioner is both irrational and kind of not; it’s not at all uncommon to look up from a sidewalk and spot an air-conditioning unit balanced precariously on a windowsill, held there in space seemingly by little more than optimism. But as Aleksander Chan specified in a 2014 Gawker story titled “You Will Not Be Killed By Falling Air Conditioners,” in the decade prior, only a handful of New Yorkers (approximately four) had been injured or killed by falling air conditioning units.

For your sake I hope that headline holds true, and statistically speaking, it probably will. But it’s nonetheless a common enough occurrence—or at least a feasible enough one—that some law firms specializing in personal injury and premises liability have published blog posts advising potential clients as to what their rights are if they have been injured by an air conditioner or another object falling from a building window two or more stories up.

Who is at fault, legally speaking, when an air conditioner falls and injures someone? It’s a surprisingly complicated question, says Michael J. Pospis, an attorney at one of those law firms—and it depends on the specifics of the case. “There’s no way to really say in all situations, this party always has the obligation,” Pospis says. If a pedestrian gets injured on the sidewalk by an air conditioner falling out of a window and takes the case to court, he explains, there are a number of potential defendants, including the building owner, the landlord, the tenant, and even in some cases the independent contractor (like a handyman or TaskRabbit serviceperson) who installed the window unit.

On the website, Pospis references two New York City cases in which building owners were accused of negligence in falling A/C cases. In 2007, a court granted summary judgment in favor of the building owners after declaring that the person struck by the falling air conditioner “did not provide a shred of evidence on the issue of constructive notice,” or didn’t prove the building owners knew the air conditioner was installed improperly. In 2009, however, a court denied a motion for summary judgment partly on grounds that the owner failed to provide evidence that they had turned over control over the apartment.

Pospis also points to a recent New York Supreme Court decision that stated that in general, it’s the landowner’s responsibility to keep their property in reasonably safe condition, unless they’ve signed over “possession and control” to someone else. When assessing a landlord’s liability for an air-conditioner accident, a court might look at the landlord’s general policy (if there is one) on inspecting and maintaining air conditioners; whether they were negligent in that inspection or maintenance; and whether or not they relinquished control of the apartment and the window in question—which, Pospis points out, “typically depends on the terms of the agreement and/or the landowner’s ability to access the premises.”

And indeed, the New York landlords’ resource LandlordsNY advises landlords to ensure, through inspection or by requiring professional A/C installation, that window units are installed in accordance with the city’s guidelines, which emphasize that air conditioning units should be supported from underneath with metal brackets or mounting rails, and those should in turn be structurally fastened to the building; they should also be affixed so that opening the window will not disturb their placement, or should be affixed to the window so that the window cannot be opened; they should not block fire escapes or other exits.

The guidelines also specify to tenants that AC units should not be supported by or used as shelves for loose objects; they also (surprisingly, perhaps, to some) advise tenants to get permission from building management before installing an AC unit. So while there’s no perfect way to prevent being hit by a falling air conditioner, you might consider these guidelines just a few small ways to be karmically proactive.

Got a weird New York anxiety that you want explored? E-mail tips@curbed.com, and we may include it in a future column.