Is your office too hot? is the tube too hot? is it illegal?

With the rising temperatures this week. The TUC has been campaigning for a change in the law 

to make it illegal.
The UK government legislation does not currently specify a maximum temperature. the Health and Safety Executive has advice on max and minimum temperatures and uses the term reasonable, its law section provides more detailed guidance. It includes a section on heat stress, the risks and official guidance.

At an international level the ILO provides guidance on international standards covering occupational Health

 on a worldwide scale this recent document considers the effect of climate change on productivity, and work standards.

 in terms of the impact of hot offices on health. Pubmed has some recent systematic reviews of scientific evidence

they include worldwide impact because of global warming.

as well as from the Lancet in December 2018 

Workers' health and productivity under occupational heat strain: a systematic review and meta-analysis. its conclusions were 'Occupational heat strain has important health and productivity outcomes and should be recognised as a public health problem. Concerted international action is needed to mitigate its effects in light of climate change and the anticipated rise in heat stress'

what about transport?
If you work in London the tube may seem too hot Transport for London  has official data on average monthly temperatures on different lines. The Central and Bakerloo are the hottest
.An FOI request retrieved information from London transport on cooling programmes

 Train operators have offered advice on why trains are delayed in hot weather

and measures they are taking. There are no specific rules on temperature apart from the general national conditions