One man, 45, another, 62, were hospitalized at UCI Medical Center.
The 62-year-old man reportedly died from his exposure. The second man was listed in critical condition.
The two men were working inside an industrial tank at Vista Paint on Orangethorpe Avenue in Fullerton.
The men were reportedly working with a paint stripping chemical when they became ill.
Authorities were called at about 2:25 p.m.
The incident was under investigation.
