title: Physiological evaluation of air-fed ensembles.
abstract: The goal of this study was to evaluate the respiratory and metabolic stresses of air-fed ensembles used by workers in the nuclear, chemical, and pharmaceutical industries during rest, low-, and moderate-intensity treadmill exercise. Fourteen men and six women wore two different air-fed ensembles (AFE-1 and AFE-2) and one two-piece supplied-air respirator (SA) at rest (REST) and while walking for 6min at oxygen consumption (V.O2) rates of 1.0 (LOW) and 2.0 l min(-1) (MOD). Inhaled CO2 (FICO2), inhaled O2 (FIO2), pressure, and temperature were measured continuously breath-by-breath. For both LOW and MOD, FICO2 was significantly lower (P < 0.03) and FIO2 was significantly greater (P < 0.008) for SA compared with AFE-1 and AFE-2 in women, while in men, similar trends were observed. Significantly lower FICO2 (P < 0.009) and significantly greater FIO2 (P < 0.04) were consistently observed in AFE-1 compared with AFE-2 in men during LOW and MOD. For both men and women, average FICO2 exceeded 2.0% in AFE-2 during MOD. During LOW and MOD, average FIO2 in AFE-1 and AFE-2 dropped <19.5% in men and women. For men and women, average inhalation pressures (PIave) were significantly greater in both air-fed ensembles than SA (P < 0.001) during REST, LOW, and MOD. Inhaled gas temperature was significantly lower in SA than in either air-fed ensemble (P < 0.001). When the air supply was shut off during walking, the time taken for minimum FICO2 to reach 2.0% was <38 s for all three ensembles in both men and women, an observation that has implications for the design of emergency escape protocols for air-fed ensemble wearers. Results show that inhaled gas concentrations may reach physiologically stressful levels in air-fed ensembles during moderate-intensity treadmill walking.
authors.affiliation: Office of Extramural Programs, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA;
authors.forename: Nina L
authors.initials: NL
authors.lastname: Turner
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Powell
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Sinkule
authors.forename: Debra A
authors.initials: DA
authors.lastname: Novak
mesh_terms: D000293:Adolescent; D000328:Adult; D000399:Air Pressure; D002245:Carbon Dioxide / Q000032:analysis; D004867:Equipment Design; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000032:analysis; D010101:Oxygen Consumption; D005082:Physical Exertion / Q000502:physiology*; D012134:Respiratory Protective Devices; D012146:Rest / Q000502:physiology*; D012737:Sex Factors; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: air-fed ensemble; oxygen consumption; protective suits; respirators; women