Section 204(b) in U.P. Building And Other Construction Workers (Regulation Of Employment And Conditions Of Service) Rules, 2009
(b)all working areas in a free air tunnel are provided with ventilation system as approved by Chief Inspector and the fresh air supplied in such tunnel is not less than 6.0 cubic meter per minute for each building worker employed underground in such tunnel and the free air flow movement inside such tunnel is not less than 9.0 meter per minute
