Key result
Lowering inhaled air temperature to 22°C in a 30°C ambient environment significantly improved perceived air quality, reduced lip and throat dryness, and increased parasympathetic activity.
Why the study?
The authors explored the importance of inhaled air temperature on thermal comfort, perceived air quality, acute non-clinical health symptoms, and physiological responses.
Does inhaled air temperature affect thermal comfort, perceived air quality, and physiological responses in human subjects?
Does inhaled air temperature affect thermal comfort, perceived air quality, and physiological responses in human subjects?
Inhaling cooler air (22°C) in a warm environment (30°C) improves perceived air quality and shifts autonomic balance toward parasympathetic activation.
May enhance perceived comfort in warm settings without whole-body changes; hypothesis-generating and should not alter practice pending larger trials.
We explored the importance of inhaled air temperature on thermal comfort, perceived air quality, acute non-clinical health symptoms, and physiological responses. Sixteen subjects stayed in a stainless-steel chamber for 90 min. They experienced four conditions with two inhaled air temperatures of 22 and 30°C and two ambient temperatures of 22 and 30°C in a 2 × 2 design. They wore breathing masks covering their mouth and nose to control the inhaled air temperature; the air was provided from an adjacent twin stainless-steel chamber. The subjects evaluated thermal conditions and health symptoms on visual-analogue scales. Skin temperature and electrocardiography were recorded. Whole-body thermal sensation and skin temperature did not change when the temperature of inhaled air was changed. Perceived air quality was significantly improved when subjects sat in the chamber at 30°C and inhaled air with a temperature of 22°C; under these conditions lip and throat dryness were significantly reduced. The lower inhaled air temperature increased time-domain heart rate variability indicators and decreased heart rate and the LF/HF ratio, suggesting that the parasympathetic nervous system was activated and the sympathetic nervous system was suppressed.
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Wu et al. (2022) studied this question. Lower inhaled air temperature (22°C) vs. Higher inhaled air temperature (30°C) was evaluated on Thermal comfort, perceived air quality, acute health symptoms, and physiological responses. Lowering inhaled air temperature to 22°C in a 30°C ambient environment significantly improved perceived air quality, reduced lip and throat dryness, and increased parasympathetic activity.
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