The system can deal with 29 hazards summarised as follows:
More detailed information about these hazards can be found in the Operating Guidance issued by the Department of Communities and Local Government:
http://www.communities.gov.uk/publications/housing/hhsrsoperatingguidance
Each hazard is assessed separately, and if judged to be 'serious', with a 'high score', is deemed to be a Category One hazard. All other hazards are called Category Two hazards.