absolute humidity

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Related to vapor concentration: saturated vapor, Vapor liquid equilibrium

humidity

 [hu-mid´ĭ-te]
the degree of moisture in the air.
absolute humidity the actual amount of vapor in the atmosphere, expressed in milligrams per liter.
relative humidity the percentage of moisture in the air as compared to the amount necessary to cause saturation, which is taken as 100.
humidity therapy the therapeutic use of water to prevent or correct a moisture deficit in the respiratory tract. Under normal conditions the respiratory tract is kept moist by humidifying mechanisms that allow for evaporation of water from the respiratory mucosa. If these mechanisms fail to work, are bypassed (such as with an endotracheal tube), or are inadequate to overcome the drying and irritating effects of therapeutic gases and mucosal crusting, some form of humidification must be provided.

The principal reasons for employing humidity therapy are: (1) to prevent drying and irritation of the respiratory mucosa, (2) to facilitate ventilation and diffusion of oxygen and other therapeutic gases being administered, and (3) to aid in the removal of thick and viscous secretions that obstruct the air passages. Another important use of water aerosol therapy is to aid in obtaining an induced sputum specimen.

Humidity therapy may be delivered in a variety of ways. Humidifiers and vaporizers increase the water content of an environment and are limited to the treatment of upper respiratory disorders because they produce particles that are too large to penetrate deeply into the lungs. Nebulizers generate clouds or mists of particles that are extremely small and thus capable of penetrating more deeply into the bronchioles and small structures of the lower respiratory tract. Examples of these include jet instruments and ultrasonic nebulizers.

ab·so·lute hu·mid·i·ty

the mass of water vapor actually present per unit volume of gas or air.

absolute humidity

the actual mass or content of water in a measured volume of air. It is usually expressed in grams per cubic meter or pounds per cubic foot or cubic yard.

ab·so·lute hu·mid·i·ty

(ab'sŏ-lūt' hyū-mid'i-tē)
The mass of water vapor actually present per unit volume of gas or air.
References in periodicals archive ?
These standard deviations quantify possible variation in measurement of water vapor concentration generated by typical PTMG instruments used in the semiconductor industry.
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Consequently, all ignition sources must be eliminated in areas where relatively high vapor concentrations may occur and only electrical equipment approved for use in explosive atmospheres should be used in these areas.
1 ppm, though vapor concentrations of 5-20 ppm were necessary to produce liver cancer in rats.
University of Minnesota, Associate Professor Lisa Brosseau, one of the authors of the study, recognized that mercury vapor concentrations could exceed occupational exposure levels when working with or near broken bulbs, especially when multiple bulbs are stored or shipped in bulk to recycling facilities.
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Atmospheric researchers say they were surprised to find water vapor concentrations climbing by 2 to 3 percent per year at altitudes of 40 to 60 kilometers--the upper stratosphere and lower mesosphere.