Cotton from the Mississippi Delta Area was washed on a continuous washing system by three different methods: (1) hot water only, (2) hot water with 1.2% bleach, and (3) hot water with 1.2% bleach and 7.5% sodium hydroxide.

The washed cottons were processed in a model card room using commercial manufacturing practices. Dust generated by the card was pneumatically transported to an adjoining climatically controlled chamber where human subjects were exposed for six-hour periods. Dust concentrations were closely controlled by blending the dust-laden air with clean air.

Preshift and postshift spirometry was performed by the subjects to determine acute changes in pulmonary function. The relationship between decrement in FEV(1) and dust concentration was established for each washing condition.