 Over the last three years, regulators have been considering things such as what the heat stress thresholds for workers should be across industries, how to plan to acclimate new employees to heat exposure, and other specifics. Business groups have opposed these efforts, saying regulations would be difficult to implement across the wide range of industries where workers are exposed to extreme heat. Five states have, on their own, implemented at least some heat-related worker protections. I'm Novosafo for Marketplace.