The regulations apply to establishments where dangerous substances are present, or are likely to be present, in quantities equal to or exceeding the quantities set out in a schedule to the regulations. The HSE explains: “There are two types (tiers) of establishment which are subject to COMAH, known as ‘upper tier’ and ‘lower tier’ depending on the quantity of dangerous substances they hold. Upper tier establishments will hold greater quantities of dangerous substances, meaning that additional requirements are placed on them by the regulations.”