Sch 2 para 15 Presence of small quantities of substances
The presence of a quantity of a hazardous substance— (a) in a location where it cannot act as an initiator of a major accident elsewhere on the relevant site, and (b) which is equal to or less than two per cent of the relevant controlled quantity for that substance, is not to be taken into account when calculating the quantity of a hazardous substance present on, over or under land for any purpose of the PHSA or these Regulations.