PADHI – HSE’s current methodology

The current methodology which HSE uses when providing land use planning advice is known as PADHI (Planning Advice for Developments near Hazardous Installations). It is based on the following principles:

• The risk considered is the residual risk which remains after all reasonably practicable preventative measures have been taken to ensure compliance with the requirements of the Health and Safety at Work etc. Act 1974 and its relevant statutory provisions.
• Where it is beneficial to do so, advice takes account of risk as well as hazard, that is the likelihood of an accident as well as its consequences.
• Account is taken of the size and nature of the proposed development, the inherent vulnerability of the exposed population and the ease of evacuation or other emergency procedures for the type of development proposed. Some categories of development (e.g. schools and hospitals) are regarded as more sensitive than others (e.g. light industrial), and advice is weighed accordingly.
• Consider the risk of serious injury, including that of fatality, attaching weight to the risk where a proposed development might result in a large number of casualties in the event of an accident.

This methodology has been codified within a software package known as PADHI+, which planning authorities can use on-line to obtain HSE advice on planning applications and pre-planning enquiries.

HSE's land use planning methodology [PDF]