An abbreviation for as low as reasonably practicable, it is a management tool used to determine the level to which risks are to be assessed and controlled. It involves a rigorous and systematic assessment of the minimization of risk and the costs in terms of time, money, and effort to achieve it. As a form of good practice requiring judgement between risk and societal benefit, it was developed through the UK parliamentary Health and Safety at Work Act (1974). Outside the UK, similar forms of engineering practice are used and this includes ALARA (as low as reasonably achievable) in the US for radiation protection.

http://www.hse.gov.uk/risk/theory/alarp.htm Official website of the Health and Safety Executive UK offering risk assessment advice.