Grahn · Journal of occupational and environmental hygiene 2018 · Controlled laboratory crossover trial · n=?

A method to reduce heat strain while clad in encapsulating outerwear.

Level 3 - non-randomized controlled study

Controlled laboratory crossover physiological study with no mention of randomization in the abstract.

PubMed 29708853 · doi:10.1080/15459624.2018.1470635 · record verified 2026-08-26

What was done

Subjects clad in encapsulating personal protective equipment (PPE) outerwear completed fixed-load treadmill exercise in a thermoneutral environment (20–24°C) or rested in a hot environment (45 ± 0.5°C). Researchers measured heat storage and the rate of core temperature rise with and without palmar glabrous skin cooling using a stationary water-circulation system, and compared this against a newly devised wearable cooling system.

What was found

Wearing PPE outerwear increased the rate of core temperature rise by five-fold during vigorous exercise. Palmar cooling via the stationary system attenuated the rate of core temperature rise by 30% to 60% during rest as well as light, moderate, and vigorous exercise while wearing PPE. The wearable cooling system demonstrated equivalent thermal benefits to the stationary system. The abstract does not provide exact participant counts, baseline or absolute core temperatures, variance metrics, or p-values.

Why it matters

Palmar glabrous skin cooling provides an effective route for heat dissipation in encapsulating PPE, and a wearable implementation could enable mobile occupational use among healthcare workers and emergency responders.

Limits

The abstract omits sample size, participant demographics, and statistical significance metrics. Findings reflect controlled laboratory conditions rather than real-world operational environments.

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