Control of Major Accident Hazards Regulations (Northern Ireland) 2000

4.  The addition of dangerous substances to determine the quantity present at an establishment shall be carried out according to the following rule:—

if the sum

q1 / Q + q2 / Q + q3 / Q + q4 / Q + q5 / Q + ...>1

where

• q_x = the quantity of dangerous substances x (or category of dangerous substances) falling within Parts II or III,

• Q = the relevant threshold quantity from Parts II or III,

then the establishment is covered by the relevant requirements of these Regulations.

This Rule will apply for the following circumstances—

(a) for substances and preparations appearing in Part II at quantities less than their individual qualifying quantity present with substances having the same classification from Part III, and the addition of substances and preparations with the same classification from Part III;

(b) for the addition of categories 1, 2 and 9 present at an establishment together;

(c) for the addition of categories 3, 4, 5, 6, 7a, 7b and 8, present at an establishment together.