Clause 1 of Schedule 1 to the Principal Regulations is amended as follows:

(a) by inserting the following definition after the definition of exempt removal work :

explosive atmosphere means a mixture with air, under atmospheric conditions, of flammable materials in the form of gas, vapour, mist, dust or fibres in which, after ignition, combustion spreads throughout the unconsumed mixture;

(b) by omitting the definition of L peak and substituting the following definition:

L _C,peak means the peak noise level;