Because they only have a few of them. Still, did you know that the MTA has tunnel fans set up which can help cool particularly hot stations? We didn't, and they do! Just not in all of the stations, and they only use them on special, super hot, occasions.

NY1 today has a piece today about the fans, which are normally meant to remove smoke from the tunnels in case of a fire, being used in the 168th Street station but not in the blisteringly hot 181st Street station yesterday. And as you can imagine, riders were not happy that the fans were not being used in the station when told of their existence. They may not bring the temperature down very much, but they do keep the air moving at least.

So what's up with them not being used? We turned to the MTA to find out, and this is what a spokesperson told us:

During the summer months, when the ambient temperature exceeds 90 degrees F°, local supervision may activate ventilation fans at 168th and 181st Sts on the 1 line in order to reduce heat and humidity on station platforms for customer comfort. The hours of operation are between 6 a.m. and 10 p.m. (On the B Division, fans may be operated at Sutphin Blvd. Jamaica Van Wyck, 21st Street, Roosevelt Island and Lexington Avenue.) This is a unique situation at these locations because of the design of the stations and the placement of the fans.

So. Now you know. And if you are at one of those stations and the temperature is really hot? Your best bet is to find a station agent and ask about them. After all, sometimes it can be hotter on the subway platforms than it is above ground—though sometimes (very rarely) the opposite can also be true. Thank goodness for those really deep stations.