The Australian Council of Trade Unions has escalated its campaign for major workplace health and safety reforms, calling for employers to be required to stop work or adjust tasks when specific high temperatures are reached.

Last year, the ACTU urged Safe Work Australia and other bodies to establish WHS regulations addressing heat-related risks using risk assessment criteria similar to those applied to hazardous manual tasks, drawing on an International Labour Organisation review which found several national frameworks "use a heat stress indicator to assess the level of exposure".

The union's push stems from a national risk assessment projecting that Australia will face more frequent and severe climate hazards, along with a substantial rise in heat-related deaths.

The ACTU stated that increasingly common heatwaves caused by climate change now represent a significant WHS threat.

"No worker should be told to push through the brutal heat and risk their own life. When it's dangerously hot, your boss should either change your work or stop your work," ACTU president Michele O'Neil said.

"A rest break or work stoppage in extreme heat can be the difference between a worker going home safe or not going home at all," she said.

"We regulate asbestos and silica because they kill people and devastate families. It's time we treat climate hazards like extreme heat in the same way.

"There is no excuse for Australia to leave workers exposed without clear, enforceable rules, especially when the [Federal] Government's own reports project heat-related deaths to more than quadruple in our major cities."

The ACTU has also advocated for dedicated workers' compensation protections for heat-related illnesses, and amendments to the National Construction Code requiring climate-resilience measures in new residential buildings.