Currently, the intensified greenhouse effect and global warming have led to increased human exposure to hazardous thermal environments.
According to research surveys, over 50 million workers in China labor under high-temperature conditions, with approximately three-fifths engaged in outdoor occupations such as mining, construction, firefighting, sports, and field exploration. In hot environments, physical labor accelerates the human metabolic rate, reduces heat tolerance, and imposes significant thermal physiological strain, resulting in diminished work endurance, productivity, and elevated accident rates. Prolonged exposure to extreme heat disrupts the body's thermal and hydroelectrolytic balance, increasing risks of dehydration, heatstroke, and severe thermal illnesses-including rashes, cramps, exhaustion, and even death.
Studies indicate that the baseline accident rate linked to ambient temperatures occurs at approximately 20°C. When temperatures exceed 28°C, accident rates rise by 30%. For example, between 2001 and 2010, 108 U.S. firefighters died during high-temperature outdoor training activities, accounting for over 11% of firefighter fatalities reported by the National Fire Protection Association (NFPA). These statistics underscore the persistent challenge of mitigating thermal stress for outdoor workers in sectors like sports, firefighting, mining, and construction-a critical priority for physiologists and occupational health professionals.
To alleviate thermal strain in high-heat occupations, methods to enhance human heat dissipation and restore thermal equilibrium are essential. Current solutions include air conditioning, ventilation fans, and personal cooling devices. However, air conditioning systems are bulky, energy-intensive, and unsuitable for outdoor environments, necessitating the development of portable, energy-efficient cooling systems. Research shows that only 1–2% of human metabolic heat is dissipated via respiration and conduction, 75% via radiation and convection, and the remainder through skin evaporation.
As clothing directly interfaces with the skin, it significantly influences heat and moisture transfer between the body and environment, making it a key factor in thermal comfort. Thus, developing Personal Cooling Systems (PCS) capable of regulating thermal comfort in hot environments is imperative. Personal Cooling Clothing (PCC), as the most energy-efficient and convenient PCS, integrates garments with cooling mechanisms to optimize the microclimate between the body and clothing. This enables wearers to self-cool, enhancing productivity and thermal-wet comfort for high-temperature workers.
The concept originated from textile applications in astronaut suits, designed to withstand extreme temperature fluctuations during orbital missions. By embedding Phase Change Materials (PCMs) into spacesuit fabrics, this technology transitioned into the civilian apparel market, driving rapid advancements in functional clothing.