Extreme heat is already the most common cause of weather-related hospitalisations in Australia and with heatwaves intensifying, our climate and environment correspondent Graham Readfearn put his body to the test in an experiment. In a climate chamber at the University of Sydney, he walked on a treadmill while temperature conditions were constantly adjusted, adding direct sunlight and higher humidity. Graham joins Nour Haydar to talk about how extreme heat affects us, our cognitive functions and our chances of survival