The Effect of Aging on the Ventilatory Response to Wearing a Chemical, Biological, Radiological, and Nuclear Hood Respirator at Rest and During Mild Exercise

Structural changes in the human body resulting from aging may affect the response to altered levels of O and CO . An abnormal ventilatory response to a buildup of CO in the inspired air due to rebreathing may result in adverse effects, which will impair the individual's ability to function under stress. The purpose of this study was to evaluate the effect of age on the respiratory response to wearing an escape hood at rest and during mild exercise. Subjects were seven healthy, young adult males (20-30 years) and seven healthy, middle-aged males (45-65 years). Inspired CO and O , breathing pattern (tidal volume [V ] and breathing frequency [F]), and mouth inspiratory and expiratory pressures, were measured at rest and during mild exercise (50 w) while wearing the CAPS 2000 escape hood (Shalon Chemical Industries and Supergum-Rubber and Plastic Technology, Tel Aviv, Israel). Resting inspired CO was higher in the middle-aged group compared with the young group (2.25% ± 0.42% and 1.80% ± 0.34%, respectively; p < 0.05). Breathing pattern in the middle-aged group tended to be shallower and faster compared with the young group (V : 0.69 ± 0.27 L and 0.79 ± 0.32 L, respectively; F: 14.7 ± 4.0 breaths/min and 12.4 ± 2.8 breaths/min, respectively). During exercise, there was a trend toward a high inspired CO in the middle-aged group compared with the young group (2.18% ± 0.40% CO and 1.94% ± 0.70% CO , respectively). A correlation was found between age and inspired CO when wearing the escape hood (r = 0.375; p < 0.05). The age-related decrease in pulmonary function, together with the finding in this study of a higher inspired CO in middle-aged subjects wearing the CAPS 2000, may represent a greater risk for persons of middle age wearing an escape hood. On the basis of this study, it would appear reasonable to recommend that new respirators be evaluated on subjects from different age groups, to ensure the safety of both young and old.