The objective of this study was to assess the effect of 20 minutes of heavy treadmill exertion in military-style, Level-C chemical and biological personal protective equipment (PPE), including a filtering face piece respirator, on physiological variables including venous pH, venous PCO2, SpO2 and tympanic temperature.

Baseline physiological variables were measured in 19 healthy subjects who undertook heavy physical exertion on a treadmill at a constant room temperature of 20°C: (1) once while wearing a short-sleeved t-shirt, shorts, and running shoes; and (2) once while wearing chemical and biological PPE. Repeat measurements of physiological variables were made after 10 and 20 minutes of exertion in both groups.

Twenty minutes of physical exertion was undertaken by healthy subjects wearing chemical and biological PPE resulted in moderate hypoxemia, significantly decreased pH (p = 0.003), elevated PCO2 (p = 0.018) and elevated tympanic membrane temperature (p < 0.001), compared to baseline values. Despite these significant differences, none of the mean venous blood gas values deviated from the normal range during physical exertion.

The degree and duration of physical exertion undertaken in chemical and biological PPE induced some significant changes in physiological variables compared to control but, with the exception of SpO2, did not result in changes considered to represent abnormal physiology. However, it is likely that core body temperature was underestimated by tympanic measurement. Blood gas data indicating that CO2 was retained during exertion in this type of PPE were unanticipated and require further investigation.