degree of hazard "degree of hazard", in relation to classification or labelling of hazardous chemicals, refers to the specific nature of the risk involved in the following order: (a) for the hazardous chemicals in Part A of Schedule I - (i) explosive, which is more hazardous than oxidising; (ii) oxidising, which is more hazardous than extremely flammable; (iii) extremely flammable, which is more hazardous than highly flammable; and (iv) highly flammable, which is more hazardous than flammable; and (b) for the hazardous chemicals in Part B of Schedule I - (i) very toxic, which is more hazardous than toxic; (ii) toxic, which is more hazardous than corrosive; (iii) corrosive, which is more hazardous than harmful; and (iv) harmful, which is more hazardous than irritant; PU(A) 143/1997 - OCCUPATIONAL SAFETY AND HEALTH (CLASSICATION, PACKAGING AND LABELLING OF HAZARDOUS CHEMICALS) REGULATIONS 1997 2. Interpretation.