Code	Occupation Description (1980)	Total # Employees (Male & Female)	Total # Female Employees
453	JANITORS AND CLEANERS	161
534	HEATING, AIR CONDITIONING, AND REFRIGERATION MECHANICS	1,042
585	PLUMBERS, PIPEFITTERS, AND STEAMFITTERS	799
596	SHEETMETAL DUCT INSTALLERS	2,136
653	SHEET METAL WORKERS	231
783	WELDERS AND CUTTERS	102
799	GRADERS AND SORTERS, EXCEPT AGRICULTURAL	244
TOTAL		4,714

*(1) The estimates for each occupation apply across the surveyed industries in which the agent was observed. Not all industries were surveyed, and not all agents were observed in all surveyed industries. (2) When using the estimates, standard errors associated with estimates should be considered. (3) Potential exposures to a chemical agent are categorized as actual (i.e., the surveyor observed the use of the specific agent) or tradename (i.e., the surveyor observed the use of a tradename product known to contain the specific agent). The estimates presented in the table combine both categories.