Section 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.