Influence of the temperature regimen on the body
High air temperature and intense thermal radiation from heated surfaces trigger the mechanisms of physical thermoregulation. Skin vessels dilate (vasodilation), and sweating increases manifold.
If compensatory mechanisms are insufficient, overheating occurs. It is accompanied by CNS depression: working capacity decreases, attention weakens, and the risks of traumatism increase. The body loses chlorides and water-soluble vitamins with sweat. Dehydration and hypochloremia develop, which lead to cramps and suppression of gastric juice secretion. This is precisely why GI diseases frequently exacerbate in the heat.
Hygienic temperature standards depend on the season (the warm period starts from a daily average temperature of +10 °C) and are divided into:
- Optimal — maintain thermal balance without straining the thermoregulation system.
- Permissible — maintain a normal thermal state, but require a physiologically permissible strain on thermoregulation.
The role of humidity in air hygiene
Humidity is evaluated using several indicators, but relative humidity—the degree of air saturation with water vapor as a percentage—has the greatest practical significance.
Extreme humidity values drastically worsen temperature tolerance:
- High humidity (>70 %) in the heat. Sweat evaporation is blocked (the air is already saturated with moisture). Profuse sweating begins: droplets roll down the skin without cooling it. The risk of heat stroke increases critically.
- High humidity in the cold. Humid air has a high heat capacity. It dampens clothing, stripping it of its thermal protection properties, and drastically increases heat loss via convection. The result is neuritis, radiculitis, and decreased immunity.
- Low humidity (<20 %). Excessively dry air dries out the mucous membranes of the respiratory tract, leading to microcracks and local infection.
Air movement velocity and wind rose
Air movement is characterized by velocity (m/s) and direction. For a specific locality, a wind rose—a graph of prevailing wind directions over the year—is constructed. This tool is mandatory for urban planning.
Wind accelerates heat loss through convection and evaporation. In the heat, this is a favorable factor, providing a feeling of coolness. In freezing weather, wind is regarded as an unfavorable factor, as it subjectively intensifies the sensation of cold and requires increased energy expenditure.
Strong wind exerts a mechanical impact: it impedes movement and alters the biomechanics of external respiration. Prolonged exposure to strong winds can provoke psychic agitation or depressive states (presumably due to infrasound generation).
Electrical state of the atmosphere
The electrical status is formed by three components: ionization, the Earth's electric field, and natural radioactivity.
The process of ionization occurs when gas molecules are split under the action of cosmic rays or UV radiation. Primary light air ions are formed.
- Resort air is rich in negatively charged light ions (2000–4000 per 1 cm³), which stimulate regeneration, improve gas exchange, and are used in the treatment of bronchial asthma.
- In dusty rooms, light ions settle on dust particles, turning into heavy positive ions. They depress the nervous system and reduce working capacity.
The Earth's electric field (average field intensity around 130 V/m) depends on altitude, season, and weather. Its sharp fluctuations, for example during thunderstorms or fogs, provoke meteotropic reactions in sensitive individuals.
Briefly: answers to topical questions
What types of maximum permissible concentrations (MPCs) are used in the hygienic standardization of atmospheric pollution?
Two types of maximum permissible concentrations are established in atmospheric air:
- Maximum single — established for substances with a sharp odor.
- General toxic daily average.
To memorize the action of air ions: a "minus" is a plus for health (negative light ions heal and invigorate), while a "plus" is a minus (positive heavy ions cause fatigue and depression).
Class and exam questions
What is the difference between optimal and permissible microclimatic conditions?
Optimal conditions provide thermal comfort without straining thermoregulation mechanisms. Permissible conditions require the activation of thermoregulation systems, but without exceeding the limits of the physiological norm.
Why does a person overheat faster in humid, hot air?
Humid air prevents the evaporation of sweat from the skin surface. Profuse sweating occurs, which does not provide a cooling effect.
What is a wind rose and why is it needed?
This is a graphical representation of the frequency of wind directions throughout the year. It is used in urban planning to locate residential zones upwind from pollution sources.
What does the loss of sodium chloride lead to during heavy sweating?
To dehydration, hemoconcentration, cramps, and suppression of gastric secretion, which disrupts the digestive capacity of gastric juice.
What else to study on this topic
- Pathogenesis of heat stroke development upon the failure of thermoregulation mechanisms.
- Changes in physical and chemical blood constants during occupational dehydration.
- Unipolarity coefficient and ionization regimen as indicators of air purity.
- Formation of the natural radiation background and the impact of radon on the habitat.
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