N.Y.C. Admin. Code § 24-143: § 24-143 Emission of air contaminant from internal combustion engine; visibility standard.

No person shall cause or permit the emission of a visible air contaminant from the internal combustion engine of:

(a) A motor vehicle while the vehicle is stationary for longer than ten consecutive seconds; or

(b) A motor vehicle after the vehicle has moved continuously for more than ninety yards.

(c) The operator or registered owner of a vehicle in violation of this section shall be responsible for such violation.