152. Permissible limit of exposure of chemicals.- The employer shall ensure at a construction site of a building or other construction work that- (a) the working environment in a tunnel or a shaft in which building workers are employed does not contain any of the hazardous substances in concentrations beyond the permissible limits as laid down in the Schedule XII annexed to these rules; (b) the responsible person referred to in rule 121 conducts necessary test before the commencement of a tunnelling work for the day and at suitable intervals as fixed by the Chief Inspector of Inspections of Building and Constructions, Delhi, to ensure that the permissible limits of exposure are not exceeded and a record of such test is maintained and is made available for inspection to the Inspector having jurisdiction, on demand. | 
