Not a big surprise, when I have used the subways in NYC, the air always has an odd smell. If I can sense it, the smell must be real bad. I have a very prro sense of smell.
Worth keeping that N95 mask on, I suppose.
Hope this encourages some miniscule semblance of climate control in some of these sweltering stations
I wonder what the source really is. NYC trains seem to already be equipped with regenerative brakes and resistor brakes:
https://www.nyserda.ny.gov/-/media/Project/Nyserda/Files/Pub...
And those don’t rub. There will surely be some emissions from the wheels rolling imperfectly on the track, but, perhaps naively, that should be small. I wonder whether NYC trains also have friction brakes that they use for the last bit of stopping. If so, perhaps improved control algorithms or improved motor drivers could avoid using them until the train is fully stopped.
There’s also another possible effect: trains produce high air velocities, and they could stir up small particles that have settled in the ground. A serious effort to clean up the tracks and stations could reduce these particles.