During a respiratory act, human at rest, passes through his lungs an air quantity of 500 cm2, volume increasing more in the conduct of an exercise, being directly proportional to the effort. In 24 hours, human is breathing about 15-25 m3 of air.
By standpoint of hygiene, air affects health both through its chemical composition, as well as by its physical properties (temperature, humidity, air currents, radiation, pressure).
In terms of chemical composition,we distinguish the influence exercised on the health of variations in concentration of normal components, as well as action exercised by the presence in air, of foreign compounds.
Direct effects are the changes that occur in the health of population due to exposure to pollutants. These changes may be translated in order of gravity through: increased mortality, morbidity, emerging or changing physio-pathological symptoms, the occurrence of direct physiological changes and / or loading the body with the pollutant agent or pollutants.
Long term effects are characterized by the occurrence of pathological events after prolonged exposure to air pollutants.These effects can be the result from accumulation of pollutants in the body, in case of cumulative pollutants (Pb, F, etc..), until loading reaches the toxic threshold. Pathological changes can also be caused by repeated impacts of harmful agents to certain organs or systems. Long-term effects occur after long periods of exposure that may be years or even decades.
Pathological manifestations can take specific aspects of pollutants (chronic poisoning, allergic phenomena, carcinogenic effects, mutagenic and teratogenic) or can be characterized by the occurrence of diseases where multiple pollutants represent one of the determinants or aggravating etiological agents (acute respiratory illness and chronic anemia, etc.).
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