The hot weather experienced by much of the UK over the summer has prompted calls by MPs and trade unions for an upper temperature limit for workplaces to be put in place. Although the law states that staff should work in a "reasonable" temperature, there is no legal limit on the maximum. The Workplace (Health, Safety and Welfare) Regulations 1992 set a lower temperature of 16 degrees Celsius -- or 13 degrees Celsius if the work involves severe physical effort -- but there is no comparable upper limit.