Temperature Regime and Humidity Favorable for Humans in Summer and Winter: Physiology, Thermoregulation, and Comfort Introduction: Homeostasis in a Changing Environment The human body maintains a constant internal temperature of about 36.6-37.0°C regardless of external conditions, meaning it is warm-blooded. This is achieved through a complex thermoregulation system, the key element of which is heat exchange with the environment. Favorable temperature and humidity parameters are not universal figures but a dynamic range within which the thermoregulation system operates efficiently, without excessive strain on the cardiovascular and respiratory systems, ensuring a subjective feeling of comfort. These parameters differ in summer and winter due to different clothing, activity, and body acclimatization. Physiological Basis of Comfort: Balance of Heat Production and Heat Loss Heat loss occurs through four main pathways: Convection (about 30%) — heat transfer to the air flowing over the skin. Radiation (about 45%) — emission of infrared rays. Evaporation (about 20%) — sweating. Conduction (insignificant) — contact with colder objects. Air humidity critically affects the efficiency of evaporative cooling. At high humidity, sweat does not evaporate but runs off the skin, failing to perform its cooling function, leading to overheating. At very low humidity, excessive evaporation of moisture from mucous membranes and skin occurs, causing dryness and discomfort. Favorable Summer Regime: Emphasis on Evaporative Cooling In warm seasons, when the body is set to release excess heat, optimal parameters shift. Air temperature: For resting in light clothing (shorts, T-shirt), the optimal range is 23-26°C. Within this interval, thermoregulation occurs mainly through convection and radiation, without active sweating. During physical activity, the optimal temperature decreases (20-23°C) to compensate for increased heat production. Relative air humidity: A key parameter. The optimal rang ... Read more