BACKGROUND: Although protocols have been published for reducing natural rubber latex exposure in medical environments, there are no objective data documenting their effectiveness. OBJECTIVE: We prospectively studied the impact of a single intervention, substitution of low-allergen-containing latex gloves for high-allergen-containing latex gloves, on latex aeroallergen levels in a single operating room (OR). METHODS: We sampled OR air on 52 consecutive days, including 33 surgery days and 19 nonsurgery days. On each surgery day all personnel wore either high-allergen gloves (n = 18 days) or low-allergen gloves (n = 15 days). Latex aeroallergen levels (in nanograms per cubic meter) and extractable latex glove allergen contents (in allergen units per milliliter) were measured by inhibition immunoassays. An on-site study monitor recorded the number of gloves used, the total time spent by all patients in the OR each day (OR time), and the total time of all procedures for each day (operating procedure time). RESULTS: Latex aeroallergen levels during low-allergen glove use days (mean, 1.1 ng/m³; median, 0.9 ng/m³; range, 0.1 to 3.5 ng/m³) were significantly lower than on high-allergen glove use days (mean, 13.7 ng/m³; median, 7.7 ng/m³; range, 2.2 to 56.4 ng/m³) (p < 0.001) but not significantly different from that on nonsurgery days (mean, 0.6 ng/m³; median, 0.3 ng/m³; range, 0.1 to 3.6 ng/m³). Latex aeroallergen levels were strongly correlated with the total number of gloves used on designated high-allergen glove days (r = 0.66, p = 0.003). There was no appreciable day-to-day carryover of latex aeroallergen. CONCLUSIONS: The substitution of low-allergen-containing latex gloves for high-allergen-containing latex gloves can reduce levels of latex aeroallergen by more than 10-fold in an OR environment. (J ALLERGY CLIN IMMUNOL 1996;98:325-30.)