Abstract
The physiological and subjective effects of working with different respirators while wearing lightweight disposable (Tyvek® 1412 polyclefin) coveralls commonly used by the asbestos abatement industry were studied. Nine healthy men (mean age=27.3 yr, weight=76.9 kg) each performed a series of four exercise tests with four different respirator ensembles in counterbalanced order. Treadmill work was performed at a set walking speed of 4 kph (2.5 mph), 0 percent elevation (220 kcal/hr), a controlled environmental temperature of 33.9°C, and 50% relative humidity. Each test continued up to 120 min, with repeated work/rest intervals of 26 min of work and 4 min of rest. Tyvek disposable coveralls and hoods were worn with each of these four different respirator ensembles: (1) control—a lightweight, low resistance mask; (2) HEPA—an air purifying, full facepicce respirator with dual high efficiency filters; (3) SAR—a supplied-air, pressure-demand respirator with escape filter; (4) SCBA—an open circuit, pressure-demand, self-contained breathing apparatus. Physiological measurements obtained every minute during each test included heart rate and skin and rectal temperatures. Subjective evaluations of clothing, respirator, and facepiece comfort, ease of breathing, temperature and perspiration in the mask and clothing, and respirator load also were measured at the end of the test. Data were analyzed using an analysis of variance. Results indicated that heart rate at the end of the test differed by less than 8 BPM between the control condition and the SCBA (heaviest) condition. Skin and rectal temperatures also were quite similar across experimental conditions (within approximately 0.2°C for skin temperature and 0.1°C for rectal temperature). Subjective ratings followed a similar trend, with only perceived respirator load being significantly different between ensembles. These results suggest that heavier, more protective respirators may be associated with only minimal additional physiological and subjective stress in selected low work load asbestos abatement industry work settings.