The act provided an exemption for medical products: restoring, correcting or modifying a physiological function by exerting a pharmacological, immunological or metabolic action.
The Act aimed to deal with a wave of new manufactured drugs by banning any substance which 'by stimulating or depressing the person's central nervous system affects the person's mental functioning or emotional state.’
Nitrous oxide can be classed as a medical exemption while commonly used to provide pain relief, nitrous oxide can affect mental performance, disorientation, vitamin B12 depletion and death - oxygen starvation.