Atmospheric pressure and meteopathic reactions
Normally, we do not feel the colossal weight of the air ocean, as the external pressure is perfectly balanced by the elasticity of fluids and gases inside our body. Natural daily (up to 5 mmHg) and annual (up to 30 mmHg) fluctuations go completely unnoticed by a healthy person.
However, people suffering from weather sensitivity act as "living barometers". When the weather changes, they face aggravated pain in old scars, fracture sites, and joints affected by rheumatism. Patients with a cardiac profile may experience cardiovascular crises, decreased sleep quality, and worsened mood.
Pressure is a key weather indicator:
- Cyclone (pressure drop) brings warm air, foreshadowing rain and overcast skies.
- Anticyclone (pressure rise) promises clear and dry weather, while in winter it turns into severe frosts.
High-altitude hypoxia and zones of physiological action
The main danger at altitude is not the pressure drop itself, but the proportional decrease in the partial pressure of oxygen ($pO_2$). It is this factor that triggers the development of mountain sickness. The severity of symptoms depends on altitude above sea level:
- Indifferent zone (0–1 km): $pO_2$ is 159–141 mmHg. The body does not need adaptation and operates normally.
- Zone of full performance (2–3 km): Compensation engages. Tachycardia (accelerated heart rate) and tachypnea (rapid breathing) are noted. Light work is accomplished without problems.
- Zone of incomplete performance (4–5 km): Exertion leads to a breakdown of compensation. Severe shortness of breath (dyspnea), muscle weakness, and coordination impairment (ataxia) appear. From the CNS side, deceptive euphoria is quickly replaced by severe drowsiness.
- Zone of non-performance (6–7 km): Pronounced severe hypoxia sets in. Any activity is ruled out, with a direct threat of loss of consciousness (syncope).
- Lethal zone (from 8 km): A drop in $pO_2$ below 56 mmHg is incompatible with life without oxygen masks and pressurized cabins.
Mechanisms of thermoregulation
Air is heated not by direct Sun rays, but by reflected heat from the earth's surface (albedo). Therefore, with increasing altitude, temperature drops steadily (by 0.6 °C every 100 m).
A human is a homeothermic creature that maintains a constant body temperature. This balance is ensured by two independent loops:
- Chemical thermoregulation (heat production): generation of heat through the oxidation of consumed nutrients. In frost, these reactions accelerate; in heat, they fade.
- Physical thermoregulation (heat dissipation): dumping excess energy from the skin surface.
At rest, the structure of heat loss looks like this:
- Radiation (emission to cold walls/furniture) — 45%
- Convection (warming of the air layer around the body) — 30%
- Perspiration (evaporation of sweat) — 25%
- Conduction (direct contact with cold objects) — a negligible fraction.
In the cold, skin vessels constrict (vasoconstriction), directing blood to internal organs and conserving heat. In the heat, capillaries dilate (vasodilation), warming the skin to dump energy.
Influence of extreme temperatures
The capabilities of homeostasis have strict limits. If the cooling capacity of the environment (especially at high humidity and strong wind) exceeds heat production, hypothermia begins.
Stages of freezing:
- Cooling of the "shell" (skin, muscles). Parenchymal organs are still warm. Pain appears when the skin cools to 15–20 °C.
- Cooling of the "core" (deep structures). A drop in core temperature to 32–33 °C is critically dangerous.
Cold strikes hard at immunity: harmless saprophytic microflora acquires virulence, provoking bronchitis, pleurisy, and nephritis. Local freezing leads to arthritis, radiculitis, and frostbite.
Danger of heat (above +25 °C): As soon as the air warms up to +30 °C, heat dissipation via convection and radiation shuts down completely. Only intensive sweat evaporation helps to survive. If this pathway is blocked, heat is trapped in the body, causing rapid overheating (hyperthermia).
Briefly: answers to topical questions
What are the natural sources of atmospheric air pollution?
Natural atmospheric pollution occurs due to natural processes and phenomena. The main natural sources include gas emission from forest fires, volcanic eruptions, and biochemical decomposition of organic matter. Another source of pollution is atmospheric dust formed as a result of rock weathering, soil erosion, forest, steppe, and peat fires.
Which industrial sectors are the main anthropogenic sources of atmospheric air pollution?
Anthropogenic atmospheric air pollution is associated with human economic activity and emissions from various industrial sectors. The main sources are ferrous and non-ferrous metallurgy enterprises, as well as the oil refining and coking industries. Additionally, fossil fuel combustion and thermal power plant emissions make a significant contribution to pollution.
What main toxic substances are contained in motor vehicle exhaust gases?
Motor vehicle exhaust gases contain a wide range of hazardous chemical compounds and are the main source of air pollution in cities. The main toxic components of exhaust include carbon monoxide, nitrogen oxides, and polycyclic aromatic hydrocarbons, among which 3,4-benzopyrene is the most hazardous. In addition, exhaust gases contain hydrocarbons involved in the formation of photochemical smog.
Which chemical substances are classified as secondary atmospheric air pollutants?
Secondary pollutants and products of atmospheric chemical and photochemical reactions include ozone, sulfuric acid aerosol, highly toxic oxidants, and peroxyacetyl nitrates. Ozone is formed during photochemical reactions involving nitrogen dioxide, and sulfuric acid aerosol is formed during the oxidation of sulfur dioxide and its combination with atmospheric moisture.
What specific pollutants are characteristic of emissions from ferrous metallurgy enterprises?
Metallurgical plant emissions are characterized by the emission of copper dust, iron oxides, lead oxides, and a complex of trace elements. The coking industry is also characterized by emissions of carcinogenic polycyclic aromatic hydrocarbons.
The acronym RCPC in order of decreasing significance will help remember the main pathways of heat loss: Radiation (45%), Convection (30%), Perspiration (25%), Conduction.
Class and exam questions
How do water bodies affect the temperature regime?
Seas and oceans act as giant heat accumulators. They smooth out daily and seasonal temperature fluctuations, forming a mild climate on the coast.
What happens at an altitude of 5 kilometers?
This is the zone of incomplete performance. Due to the low partial pressure of oxygen, a person experiences shortness of breath, muscle weakness, impaired movement coordination, and drowsiness after brief euphoria.
What else to study on this topic
- Occupational hazards in caisson and diving operations (the effect of hyperbaria)
- Pathogenesis of the transformation of saprophytic microflora into virulent flora during hypothermia
- Specifics of flight crew training in altitude chambers
- Principles of rational clothing and nutrition for the prevention of hypothermia
- Influence of latitude and albedo on climate formation in different regions of the Earth
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Other topics in "Chapter 1. Ecological and hygienic problems of atmospheric air"
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