The assault occurred on a crowded No. 3 train near the Chambers Street station during Tuesday's morning rush.
Witnesses told the Daily News and the New York Post that an argument quickly escalated when Evelyn Seeger asked the man not to smoke. The witnesses say two riders were trying to restrain the man when he pulled out a pen and slashed Seeger's face.
Seeger, of Nutley, N.J., was treated at a hospital and released.
Police charged the man with felony assault and criminal possession of a weapon.