Workplace air safety in motor transport undertakings requires controlled exhaust systems and reduced exposure to hazardous fumes before entry. The employer of every motor transport undertaking must maintain precautions against dust, noxious gas, fumes and other impurities. Exhaust systems for flammable fumes, gases, mists, vapours or residues must not be connected to other ventilating systems or discharged into chimneys or flues used for combustion gases. Where discharge may harm health or the neighbourhood, it must pass through a system that neutralises toxic substances, sterilises infectious substances and deodorises fumes, gases, mists or vapours. No employee may enter a workplace or confined space until harmful levels are reduced within permissible limits.