Recent NIOSH science blogs have discussed the physiological impact of wearing respirators. The first blog in this vein explored the Physiological Burden of Prolonged PPE Use on Healthcare Workers during Long Shifts, including potential CO2 buildup. A second blog addressed Heat Stress Imposed by PPE Worn in Hot and Humid Environments and how healthcare workers and their employers can recognize and mitigate potential stressors. As a third installment of this series, this blog addresses the general physiological responses to cold stress while working in cold environments and how personal protective equipment (PPE) can provide some protection.