Serving as personal protective equipment (PPE) to guard against heat stress, air-conditioning vests circulate cool air to minimize temperature-related stress and fatigue. The vests use a vortex tube to reduce the temperature of the air circulating through the vests, which diffuses the airflows around the worker’s torso. The circulating air is up to 60°F cooler than ambient. Plasticized vests are available in three sizes and provide continuous cooled or warmed air through its perforated lining. Dual-action vests can switch from cold to hot to provide comfort in all seasons.