4. In the case of an establishment where no individual substance or preparation is present in a quantity above or equal to the relevant controlled quantity for that substance or preparation, the addition of hazardous substances to determine the controlled quantity shall be carried out according to the following rule:
If the sum—q1/Q + q2/Q + q3/Q + q4/Q + q5/Q + ... ≥ 1
(where qx = the quantity of hazardous substance x (or category of substance) present, Q = the relevant controlled quantity (Q) from Part A or B, except for those substances for which column 3 of Part A contains a quantity Q*, in which case the quantity Q* shall be used in place of the controlled quantity Q in column 2)
then the controlled quantity of each of the substances which are added together in accordance with each of paragraphs 5(a) to (c) below shall be deemed to be present for the purposes of sections 108(1), 112(2)(a), 117(2)(a) of the 2011 Act and of section 149 (enforcement notice to have effect against subsequent development) of the 2011 Act as modified by regulation 17(1) and Part 2 of Schedule 3 to these Regulations.