LUP image

HSA Approach to Land Use Planning

A new Guidance Document on Technical Land-Use Planning advice has been published. This Guidance interprets the Health and Safety Authority (HSA) policy on technical land-use planning (TLUP) advice under the Seveso-III Directive and it replaces the Policy & Approach of the Health & Safety Authority to COMAH Risk-based Land-use Planning (19 March 2010).

Guidance on technical land-use planning advice

Changes in the revised Guidance

Emphasis has been placed on maintaining a rigorous and consistent risk-based approach across all sectors. 

The more significant changes relate to:

  • Guidance on major accident scenarios relevant to TLUP, frequencies of occurrence and the modelling parameters to be used. (The Guidance consistently and closely follows the approach set out in the event trees of the Purple Book[1] and BEVI[2])
  • Links to planning and development legislation.
  • New sections added on the LNG, Recovered Natural Gas (RNG), Distillery/Warehouse sectors, Ammonia Refrigeration Plant and Hydrogen Fuel (future new sections can be slotted in to the framework as new sectors emerge.)
  • A single approach to development of risk zones for fertiliser establishments
  • Flammable liquid categories follow the CLP Regulation categories and related ignition probabilities are specified.
  • Ambient temperatures for consequence modelling are specified.
  • Updated and shorter list of Probit equations (for converting toxic dose to percentage lethality) included.
  • The preventive approach to MATTEs. Risk-based environmental assessment and NATECH accidents.
  •  References to information sources for flood mapping and historical rainfall included and historic storm gust data including a multiplier to account for climate change effects.
  • A revised approach to societal risk using Expectation Value (‘EV’) and FN curves is introduced, to ensure a clearer understanding and consistent with the approach described in the Significant Modifications Guidance published in 2019.

  • The Public Information Zone is linked to the outer land-use planning zone (and the term ‘specified area’ replaced and previous guidance withdrawn).Exposure duration for thermal radiation outdoors reduced from 75 seconds to 60 seconds, to bring it closer to the approach used in the BEVI and by the UKHSE.


[1]TNO, ‘Guideline for Quantitative Risk Assessment’, CPR 18E, 1999 (Purple Book)

[2]BEVI (2009): Reference Manual Bevi Risk Assessments, versions 3.2. RIVM (Bevi 3.2)