Air Filtration:-

A particulate air filter is a device composed of fibrous materials which remove solid particulates such as dust, pollen, mold, and bacteria from the air. Filters containing an absorbent or catalyst such as charcoal (carbon) may also remove odors and gaseous pollutants such as volatile organic compounds or ozone.[1] Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.
Some buildings, as well as aircraft and other human-made environments (e.g., satellites and space shuttles), use foam, pleated paper, or spun fiberglass filter elements. Another method, air ionizer’s, use fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and air compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid dynamics of the air-compressor part of the gas turbines.

 

Quality of Air we Breathe:
Indoor air quality (IAQ) is a term which refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. IAQ can be affected by gases (including carbon monoxide, radon, volatile organic compounds), particulates, microbial contaminants (mold, bacteria), or any mass or energy stressor that can induce adverse health conditions. Source control, filtration and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality in most buildings. Residential units can further improve indoor air quality by routine cleaning of carpets and area rugs.
Determination of IAQ involves the collection of air samples, monitoring human exposure to pollutants, the collection of samples on building surfaces, and computer modeling of air flow inside buildings.
IAQ is part of indoor environmental quality (IEQ), which includes IAQ as well as other physical and psychological aspects of life indoors (e.g., lighting, visual quality, acoustics, and thermal comfort).[1]
Indoor air pollution in developing nations is a major health hazard.[2] A major source of indoor air pollution in developing countries is the burning of biomass (e.g. wood, charcoal, dung, or crop residue) for heating and cooking.[3] The resulting exposure to high levels of particulate matter resulted in between 1.5 million and 2 million deaths in 2000.[4]

 

Water content of our Air:-

A humidifier is a device that increases humidity (moisture) in a single room or an entire building. In the home, point-of-use humidifiers are commonly used to humidify a single room, while whole-house or furnace humidifiers, which connect to a home’s HVAC system, provide humidity to the entire house. Medical ventilators often include humidifiers for increased patient comfort. Large humidifiers are used in commercial, institutional, or industrial contexts, often as part of a larger HVAC system.
Humidifier in an art museum in Augsburg, Germany
Low humidity may occur in hot, dry desert climates, or indoors in artificially heated spaces. In winter, especially when cold outside air is heated indoors, the humidity may drop as low as 10-20%. This low humidity can cause adverse health effects, by drying out mucous membranes such as the lining of the nose and throat, and can cause respiratory distress.[1] The low humidity also can affect wooden furniture, causing shrinkage and loose joints or cracking of pieces.[2] Books, papers, and artworks may shrink or warp and become brittle in very low humidity.[3]
In addition, static electricity may become a problem in conditions of low humidity, destroying semiconductor devices and causing static cling of textiles, and causing dust and small particles to stick stubbornly to electrically charged surfaces.[4]
Overuse of a humidifier can raise the relative humidity to excessive levels, promoting the growth of dust mites and mold, and can also cause hypersensitivity pneumonitis (humidifier lung).[5] A relative humidity of 30% to 50% is recommended for most homes.[6] A properly installed and located hygrostat should be used to monitor and control humidity levels automatically, or a well-informed and conscientious human operator must constantly check for correct humidity levels.