Code	Occupation Description (1980)	Total # Employees (Male & Female)	Total # Female Employees
453	JANITORS AND CLEANERS	670	36
505	AUTOMOBILE MECHANICS	142
534	HEATING, AIR CONDITIONING, AND REFRIGERATION MECHANICS	1,703
549	NOT SPECIFIED MECHANICS AND REPAIRERS	856
558	SUPERVISORS, N.E.C.	1,786
575	ELECTRICIANS	16
585	PLUMBERS, PIPEFITTERS, AND STEAMFITTERS	493
596	SHEETMETAL DUCT INSTALLERS	3,656
597	STRUCTURAL METAL WORKERS	1,367
653	SHEET METAL WORKERS	5,093
779	MACHINE OPERATORS, NOT SPECIFIED	1,077
783	WELDERS AND CUTTERS	9,352	8
785	ASSEMBLERS	1,793
787	HAND MOLDING, CASTING, AND FORMING OCCUPATIONS	812
869	CONSTRUCTION LABORERS	4,393	5
889	LABORERS, EXCEPT CONSTRUCTION	179
TOTAL		33,389	50

*(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.