[Berlin_Freeper]

Howard Webb is bent double with pain and can barely stand up. Sweat pours from his chin, dripping down his arms and his legs.

The 42-year-old referee gasps for air as the heat in this tiny room at Sheffield Hallam University's Faculty of Health and Wellbeing rises and the humidity spirals.

"It is tough, it is very tough," he says. "The heat and humidity are going to be the biggest challenges in Brazil. We all know that."

Webb leaves for Brazil in three days as England's sole refereeing representative.

[Berlin_Freeper]

Heat Wave Kills 32 Elderly People in Brazil