Filtration and air cleaning are used to improve indoor air quality and occasionally to enable a reduction in rates of outdoor air ventilation. This Position Document addresses the health consequences of filtration and air cleaning. Data from refereed archival literature are used to form summary statements on performance as well as the positions with respect to specific technologies. One key statement is that, at present, there is only significant evidence of health benefits for porous media particle filtration systems.
Air is ionized when an electron is added to or removed from any of its constituent atoms or molecules. The charged particles so formed usually attract to themselves between four and 12 other gaseous molecules to form a cluster of comparatively low mobility; the ratio of ions to
non-ionized molecules is low and rarely exceeds 1 part in 1012 even when enhanced artificially (Kreuger, 1962). The atmosphere at ground level is at all times ionized to some degree, the ion concentration mainly depending upon natural factors such as the abundance of radioactive elements and cosmic rays and also upon atmospheric conditions such as humidity and the concentration of dust particles.
Airborne contaminants occur in the gaseous form (gases and vapours) or as aerosols. In scientific terminology, an aerosol is defined as a system of particles suspended in a gaseous medium, usually air in the context of occupational hygiene, is usually air. Aerosols may exist in the form of airborne dusts, sprays, mists, smokes and fumes. In the occupational setting, all these forms may be important because they relate to a wide range of occupational diseases.
Some cloudy and rainy days, you don’t feel like getting up. You feel lethargic, tired, and not very cheerful. Scientists attribute this to ‘positive ion poisoning’. Ions are microscopic particles that carry an electric charge. In air, ions are created when enough energy acts upon molecules of air and displace an electron which attaches to a nearby stable molecule that gets a negative charge.
June 2019, ASHRAE journal article.