5. Why Are There Thermometers on the Ceiling?

The tiny thermometer stickers on the ceiling of subway cars are not, as some have suggested, a guerrilla art installation, the work of an organization trying to start a movement against global warming or buttons. They are HVAC (heating, ventilation and air-conditioning) target-temperature decals. These decals were installed in 2008 in every car that has air conditioning, according to MTA spokesman Kevin Ortiz. Using a laser, MTA employees scan these stickers to figure out the temperature of the subway car and then make adjustments as necessary to keep it between 58 – 78 degrees Fahrenheit.

The stickers are placed in the same general spots for each car, one at the center of the car and two others at either end near the heating and air-conditioning systems, to ensure that temperature readings from different trains can be held to the same standard.