The hazard
Summer brings long days, high heat, strong sun, storms, bugs and new seasonal workers who do not know the site yet. Heat illness can come on fast, and a tired, overheated worker is more likely to make mistakes. There is no final federal OSHA heat standard, but water must be provided and the general duty to train still applies. Some states have their own heat rules, so check yours.
The action
Workers who are new, or back from time off, have not built up to the heat yet. Give them lighter work and more breaks the first few days, and pair them with someone experienced. Walk summer hires through the site and its hazards before they start. In construction, the employer must instruct each employee in recognizing and avoiding unsafe conditions. (29 CFR 1926.21(b)(2))
ASK THE CREW
Who on our crew is new or just back from time off?
From the talk: Summer safety. Read it in full, free, with the questions and the sign-in sheet.