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HHSRS definition of hazards

How hazards are defined and grouped under the Housing Health and Safety Rating System (HHSRS).

This content applies to England & Wales

The Housing Health and Safety Rating System

The Housing Health and Safety Rating System (HHSRS) is a system for assessing housing conditions. 

Under the HHSRS a local authority:

  • carries out inspections of rented housing

  • identifies whether any specified hazards are present

  • categorises those hazards according to objective criteria

A hazard is any risk of harm to the health or safety of an actual or potential occupier of accommodation that arises from a deficiency in the dwelling, building or land in the vicinity. Health includes mental health.[1]

The HHSRS is not intended to provide a single standard but to identify hazards and their likely impact on the health and safety of the occupier or visitor in residential accommodation.[2] The cost of remedy is immaterial to the assessment.[3]

The underlying principle is that 'any residential premises should provide a safe and healthy environment for any potential occupier or visitor'[4] A dwelling should:

  • be designed, constructed and maintained with non-hazardous materials

  • be free from both unnecessary and avoidable hazards

  • provide adequate protection from all potential hazards prevailing in the local environment[5]

The HHSRS is concerned with hazards that are attributable in whole or in part to the design, construction and or maintenance of the dwelling. These would normally be the responsibility of the owner or landlord to remedy.[6]

The HHSRS is not concerned with hazards attributable to the behaviour of the occupants or neighbours.

Circumstances giving rise to hazards

The regulations list 29 'matters and circumstances' that give rise to hazards.[7]

These are grouped by the HHSRS Operating Guidance according to their nature.[8]

The four groupings are:

  • physiological requirements

  • psychological requirements

  • protection against infection

  • protection against accidents

Physiological requirements relate to hygrothermal conditions and non-microbial pollutants. Psychological requirements relate to space, security, light and noise. Protection against infection covers hazards associated with hygiene, sanitation and water supply. Accidents relate to risks associated with falls, electric shocks, fires, burns, scalds, collisions, cuts and strains.

The guidance also gives in respect of each matter and circumstance:

  • a description of the hazard

  • potential for harm, on a statistical basis

  • causes, including possible contributory causes by human behaviour

  • preventative measures and the ideal

  • relevant matters affecting likelihood and harm outcome - factors that increase or reduce the risk and severity of the harm attributed to this hazard

  • guidance to assist in the assessment of the hazard[9]

The government has published guidance for non-specialist users that offers further explanation of how hazards are defined, grouped and assessed. 

Hygrothermal conditions 

Hygrothermal conditions are conditions that affect how heat and moisture travel though buildings. 

(1) Damp and mould growth – this includes threats to health from house dust mites and mould or fungal spores resulting from dampness or high humidity.

(2) Excess cold – threats to health from sub-optimal indoor temperatures.

(3) Excess heat – threats to health from excessively high indoor air temperatures.

Pollutants (non-microbial)

(4) Asbestos and manufactured mineral fibres (MMF) – covers the presence of and exposure to asbestos fibres and manufactured mineral fibres within dwellings.

(5) Biocides – this covers threats from those chemicals used to treat timber and mould growth, but not insecticides or rodenticides used to treat pests.

(6) Carbon monoxide and fuel combustion products – includes hazards from the presence of excessive levels in the indoor atmosphere of carbon monoxide, nitrogen dioxide, sulphur dioxide and smoke (not smoke from cigarette or pipe smoking).

(7) Lead – threats to health from the ingestion of lead eg from lead based paints or pipework.

(8) Radiation – covers threats from radon gas and its daughters primarily airborne. The Operating Guidance states there is no evidence to justify including electromagnetic fields from power lines or mobile phone masts. Leakage from microwave ovens might be considered where the oven is provided by the landlord but the incidence of significant microwave leakage is very rare.

(9) Uncombusted fuel gas – covers the threat of asphyxiation resulting from the escape of fuel gas.

(10) Volatile organic compounds - this covers threats from a diverse range of organic chemicals including formaldehyde, which are gaseous at room temperature and can be found in a variety of materials in the home.

Space, security, light and noise

(11) Crowding and space – covers hazards associated with lack of space within the dwelling for living, sleeping, and normal household life.

(12) Entry by intruders – covers difficulties in keeping a dwelling secure against unauthorised entry.

(13) Lighting – includes threats to physical and mental health associated with or inadequate natural or artificial light.

(14) Noise – includes threats to physical and mental health as the result of exposure to noise inside the dwelling or within its cartilage.

Hygiene, sanitation and water supply

(15) Domestic hygiene, pests and refuse – this covers hazards resulting from poor design, construction and layout so that the dwelling cannot be readily kept clean; access into and living places within the dwelling for pests; and inadequate and unhygienic provision for storing and disposal of household waste.

(16) Food safety – covers threats of infection resulting from inadequacies in provision and facilities for the storage, preparation and cooking of food.

( 17) Personal hygiene, sanitation and drainage – includes threats of infection and to mental health associated with personal hygiene, including personal and clothes washing facilities, sanitation and drainage but not problems of pests associated with defective drainage.

(18) Water supply for domestic purposes – covers the quality and adequacy of the supply of water within the dwelling for drinking and domestic purposes, such as cooking and washing. Quality includes threats to health from chemical and microbiological pollutants.


(19) Falls associated with baths etc – this covers any fall associated with a bath or shower or similar facility.

(20) Falls on level surfaces – includes falls on any level surface such as floors, yards and paths, and includes falls associated with trip steps, thresholds or ramps where the change in level is less than 300mm (about one foot).

(21) Falls associated with stairs and steps – covers any fall associated with stairs, steps and ramps where the change in level is greater than 300mm (about one foot) and includes falls associated with internal stairs and ramps, external steps and ramps within the curtilage, internal common stairs or ramps in the building containing the dwelling, including internal and external stairs providing a means of escape in case of fire or access to shared amenities. It includes falls over ballustrading on stairs or steps but not falls over balconies or from landings.

(22) Falls between levels -–covers falls from one level to another inside or outside the dwelling where the difference in level is more than 300mm (about one foot), eg falls out of windows, from balconies, landings and accessible roofs.

Electric shocks, fires, burns and scalds

(23) Electrical hazards – includes hazards from shock and burns resulting from exposure to electricity including lightning strikes.

(24) Fire – covers threats from exposure to uncontrolled fire and associated smoke in a dwelling, including injuries from clothing catching alight on exposure to an uncontrolled fire, but not injuries caused by clothing catching alight from a controlled fire or flame, such as when reaching across a gas flame on a cooker.This hazard covers defects to the electricity supply, meters, fuses, wiring, sockets or switches.

(25) Flames, hot surfaces and materials – covers threats of burns caused by contact with a hot flame or fire and contact with hot objects or non-water based liquids, and scald injuries caused by contact with hot liquids and vapours.

Collisions, cuts and strains

(26) Collision and entrapment – includes risk of physical injury from trapping body parts in building features such as doors or windows and from striking or colliding with objects such as windows, doors, low ceilings, low door frames and walls.

(27) Explosions – covers the threat from the blast of an explosion, from the debris generated by the blast and from the partial or total collapse of a building as the result of an explosion.

(28) Ergonomics – includes threats of physical strain associated with functional space poor location of fittings and amenities and other features in dwellings.

(29) Structural collapse and falling elements – covers the threat of the whole or part of the dwelling collapsing, or of an element or part of the fabric being displaced or falling because of inadequate fixing, disrepair or as the result of adverse weather conditions.

Last updated: 16 March 2021


  • [1]

    s.2 Housing Act 2004.

  • [2]

    s.1(4) Housing Act 2004.

  • [3]

    para 1.18 HHSRS Operating Guidance - Housing Act 2004: Guidance about inspections and assessment of hazards given under Section 9, February 2006.

  • [4]

    para 1.12 HHSRS Operating Guidance - Housing Act 2004: Guidance about inspections and assessment of hazards given under Section 9, February 2006.

  • [5]

    para 1.13-1.17 HHSRS Operating Guidance - Housing Act 2004: Guidance about inspections and assessment of hazards given under Section 9, February 2006.

  • [6]

    para 2.32-2.36 Housing Health and Safety Rating System Operating Guidance, February 2006.

  • [7]

    reg 3(1) and Sch.1 Housing Health and Safety Rating System (England) Regulations 2005 SI 2005/3208; reg 3(1) and Sch.1 Housing Health and Safety Rating System (Wales) Regulations 2006 SI 2006/1702 (W.164).

  • [8]

    HHSRS Operating Guidance – Housing Act 2004: Guidance about inspections and assessment of hazards given under Section 9, February 2006.

  • [9]

    Annex D Housing Health and Safety Rating System Operating Guidance, February 2006.