Effect of respiratory protective devices on development of antibody and occupational asthma to an acid anhydride.

STUDY OBJECTIVES To determine whether the use of respiratory protective equipment would reduce the incidence of occupational asthma due to exposure to hexahydrophthalic anhydride (HHPA). DESIGN Prospective cohort study. SETTING A facility that makes an epoxy resin product requiring HHPA for its manufacture. PARTICIPANTS Sixty-six individuals newly hired at a facility that makes an epoxy resin product requiring HHPA for its manufacture. INTERVENTION Employees who wished to use respiratory protective equipment could choose from three types of masks: dust mask, half-face organic vapor respirator, or full-face organic vapor respirator. MEASUREMENTS Workers were evaluated annually for development of positive antibody to HHPA and occupational, immunologic respiratory disease, including occupational asthma. RESULTS With use of respiratory protective equipment, the rate of developing an occupational immunologic respiratory disease was reduced from approximately 10 to 2% per year. Occupational asthma developed in only three individuals, and they were all in the higher exposure category. Statistically, one respirator was not superior to the others. CONCLUSION Respiratory protective equipment can reduce the incidence of occupational immunologic respiratory disease, including occupational asthma, in employees exposed to HHPA.