The chemical industry plays a major part in all our lives but, as well as the benefits, it also creates hazards.
The safety implications of land use development in the vicinity of major accident hazard sites were first recognised in the late 1960s. In 1972 planning authorities were advised to consult HM Factory Inspectorate (now part of HSE), before granting planning permission for certain classes of development (known as major hazards) and for other development in the vicinity of existing major hazard sites.
The flammable, oxidising, explosive or toxic properties of the substances used and produced by the chemical industry are such that accidents involving even relatively small quantities of these materials may have the potential to cause harm to people, property, or the environment.
Where these substances are present on the scale associated with the major chemical industries, the consequences of major accidents may potentially rival those of natural disasters in terms of loss of life, injury and damage to property over a wide area. This has been demonstrated in major accidents that have occurred in the UK at Flixborough (1974) and Buncefield (2005), across Europe at Seveso (1976), Enschede (2000) and Toulouse (2001), and elsewhere, Bhopal (1984), Mexico City (1984) and West, Texas (2013).
In the UK much has already been achieved through controls under the Health and Safety at Work Etc. Act 1974, and associated legislation, to reduce the likelihood of major accidents and to mitigate the consequences of those which do occur, by emergency planning and providing information to people in the surrounding area.
However, the consequences of major accidents can also be mitigated through land-use planning; making decisions about the location of major hazard installations and about the development of land around them.
Ideally, industries using large quantities of hazardous substances would be located far away from centres of housing and other developments that could be affected in the event of an accident. In reality, factories, housing, schools and shops have developed close to each other; indeed, in many cases these industries provide the economic heart of the local community.
On the other hand, there are pressures on the land available for development for housing, retail and public use, etc. This can lead to demands for available land around existing hazardous installations to be used for purposes, such as large housing developments or schools, which HSE does not consider compatible with the presence of a hazardous installation.
Greater control is possible when planning the location of new hazardous activities, but the options may be limited. There are few locations to site new hazardous installations without creating some risk to an existing community. The UK is a small, densely populated island and the undeveloped areas that do exist are often so remote as to be economically unviable, or of such environmental value as to be unsuitable for industrial use.
All of this means that in making planning decisions about siting new hazardous installations, or the development of land around existing ones, safety is among a number of elements to be considered by local planning authorities, albeit one that should be given great weight.
A balance has to be struck between the needs of industry, the needs of the community and the interests of safety. HSE's role is therefore to provide advice that will allow local planning authorities to make an informed decision in respect of the planning process whilst fully understanding the risks as presented by HSE.
In 1974 an explosion at a chemical works in Flixborough, Humberside killed 28 people on site and caused extensive damage to properties some distance away. Following this, a committee of experts, the Advisory Committee on Major Hazards (ACMH) was established to review all aspects of safety at and around major hazard sites. The ACMH produced three reports in which they proposed a strategy which included the mitigation of the consequences of any major accidents that could occur.
Control of development in the vicinity of major hazard sites was identified as a key element in mitigation. The ACMH established principles which still govern HSE’s policy in this area; they recognised that complete ‘sterilisation’ of land around such sites was not practicable but that ‘The overall objective should always be to reduce the number of people at risk’ and ‘it is wise to avoid a substantial growth in population near an existing installation’.
Arrangements were introduced for local planning authorities to consult HSE for advice about risks from major hazard sites and the potential effect on populations nearby when considering applications for planning permission around such sites.
Following a series of major incidents in Europe, including a catastrophic accident in Seveso, Italy in 1976, legislation was adopted aimed at preventing and controlling such accidents. In June 1982 the European Commission Directive on the Major Accident Hazards of Certain Industrial Activities (82/501/EEC) was adopted. Known as the Seveso Directive, after the Italian accident, it required EC Member States to ‘ensure that the objectives of preventing major accidents and limiting the consequences of such accidents were taken into account in their land-use policies and/or other relevant policies’. The measures which should be taken to achieve these objectives included controls on new developments in the vicinity of existing hazardous installations and on the siting of new hazardous installations.
The Directive was replaced in 1996 by Seveso II (96/82/EC). Seveso II took account of lessons learned from later accidents and was implemented in the UK (in respect of the health, safety and environmental aspects) by the Control of Major Accident Hazards Regulations 1999 (COMAH). The land use planning requirements were implemented separately by planning legislation.
In July 2012, the Seveso III Directive (2012/18/EU) was adopted. This replaces Seveso II and is implemented in the UK through the Control of Major Accident Hazards Regulations 2015 (COMAH) and relevant planning legislation.
HSE carried out a fundamental review of its role in land use planning which concluded that land use planning work should be devolved to the local planning authorities. This would streamline the planning process and allow local authorities to access HSE advice directly through codified guidance made available to their systems.
The final changes were implemented in 2007 when planning authorities were provided with access to PADHI+, an internet-based standing advice tool through which HSE’s advice on land use planning could be obtained.
In 2015, HSE replaced PADHI+ with the HSE Planning Advice Web App, which both planning authorities and potential developers can use to obtain HSE’s land use planning advice on developments around major hazard sites and major accident hazard pipelines.
As part of the fundamental review, several reviews were undertaken of various aspects of how HSE provided land use planning advice.
An independent expert was commissioned to review HSE’s approaches to analysing hazard and risk in relation to land use planning. The purpose of this review was to look at how HSE currently undertook its analyses, how well they were performing, and if any improvements could be made.
Overall the review concluded that HSE’s approaches and methods for assessing risks were fit for purpose. In the majority of circumstances they were found to be neither overly optimistic nor pessimistic in their predictions when compared to those used by others. Some specific points were however raised where it was felt that improvement was possible or necessary, and a series of recommendations were made. HSE's response to the review is contained in the following document:
HSE undertook a review of the modes and methodologies used in setting consultation distances around major hazard sites, in order to obtain a robust picture of their relative strengths and weaknesses, and prioritise their development.