N.Y.C. Admin. Code § 27-446: § 27-446 Ventilation.

All spaces used for the repair of motor vehicles shall be provided with mechanical ventilation adequate to provide four air changes per hour.

(a) Exhaust gases. Where engines are to be run for test purposes or adjustments, provisions shall be made to collect the exhaust gases from each vehicle and to discharge such gases to the outer air by means of a positively induced draft. The discharge opening from such system shall be located as required by subchapter thirteen of this chapter.

(b) Pits. All pits for inspection or repair shall have mechanical exhaust ventilation taken from near the bottom of the pits. Pit exhaust systems shall be adequate to provide at least four air changes per hour.