Is it just me or is this wrong?

I work in a Glasshouse picking tomatoes and it's the new season so the bosses keep the roof closed to speed up growth but the temp hits around 60-70*c (140f – 158f) with no air flow, think hot car with the windows up and i ask to go home as its too hot for me, my supervisor has told me that i have to get use to the heat but i can't stand working in 60*c for 10 hours, surly this has to be unsafe