I can't imagine them not needing supplied air and full coverage, if there
is potential exposure. As well as a spotter and rescue plan and ventilation. My condolences, and may he rest in peace.
"Employees who work at the smelter are required to wear a respirator while
performing their duties, he said."That's dependent on the
concentration of the sulfur dioxide. It's nasty stuff, and in a lot of
cases, especially in industrial use, it requires a full coverage, fresh air
supply system. I'm betting the poor guy was using the wrong kind of
protection for his exposure level. RIP.