Indoor air cleaners are used to eliminate harmful materials in the air that can become health hazards. Types of cleaners range from simple filters to electronic ionization air cleaners to gas-phase air filters. Polluted air can lead to a variety of different health problems, such as asthma or allergies. Some air purifiers are installed in the central heating area of an indoor location, while portable air filters typically clean the air of a specific area or room.
Pollutants that affect indoor air quality are usually grouped into two categories: particulate matter and gaseous pollutants. Particulate matter includes small particles from such things as dust mites, animal dander, tobacco smoke and pollen. Gaseous pollutants include gas cooking stoves, pesticides, cleaning products and vehicle exhaust.
There are various types of indoor air cleaners, each designed to eliminate a certain kind of pollutant. For particulate matter, there are mechanical and electric indoor air cleaners. Mechanical cleaners, specifically in the form of filters, remove the particles of pollutants by capturing them in the filter. High Efficiency Particulate Air (HEPA) filters are an example of this.
Electronic air cleaners use an electrostatic process to trap charged pollutant particles. The particles become charged when air is pulled through a cleaner, such as an electrostatic precipitator, via an ionization process. These charged particles then are released back into the air to attach and clean the polluted particles.
Gas-phase air filters are indoor air cleaners that are typically used to get rid of gaseous pollutants. These cleaners use a sorbent, such as activated carbon. The sorbent works to clean the air by absorbing the pollutants. Some pollutants, such as carbon monoxide, might not be completely eradicated by gas-phase air filters, so additional cleaning methods might be needed.
Ultraviolet (UV) light technology is also sometimes used to destroy pollutant particles. This method destroys particles with ozone gas, which is generally considered to be a lung irritant. Examples of indoor air cleaners that use UV light technology include Photocatalytic Oxidation (PCO) cleaners and Ultraviolet Germicidal Irradiation (UVGI) cleaners.
PCO cleaners use a catalyst substance which reacts to light produced by a UV lamp. Typically, the main goal of these cleaners is to eradicate gaseous pollutants, not particulate pollutants. The eradication is usually done by converting the pollutants into a harmless forms. UVGI cleaners use radiation from UV light to destroy particles that originate from things like bacteria, viruses, or mold. It is usually suggested that they be used with additional filtration processes.