Air purifier

An air cleaner helps make the air in a room better.

It pulls in air that has dust or smoke. Some machines use a special filter to catch these bits. These filters can trap tiny things like pollen or mold.

This helps people who feel sick from dust. Some machines also use light to clean the air. These tools can be small or very large. They help keep the air inside our homes clean and fresh.

It is a very useful machine.

An air purifier is a device that cleans the air. It removes things like dust, pollen, and smoke. This helps people with allergies or asthma.

There are two main ways these machines work. Some are active. They release charged ions into the air. These ions make pollutants stick to surfaces. Other machines are passive. They use filters to catch particles. Passive machines are very efficient. They trap dust and keep it in the filter.

A common type of filter is a HEPA filter. HEPA stands for high-efficiency particulate air. These filters can catch 99.97 percent of tiny particles. They are very good at cleaning the air. Some machines also use light to clean. This is called UVGI. It uses ultraviolet lamps to kill germs.

Air purifiers can be small units for a room. They can also be very large. Big units connect to air systems in hospitals. Some machines even use carbon. Carbon can soak up chemicals from the air.

An air purifier is a machine that cleans the air in a room. It removes tiny things like dust, pollen, and pet dander. These things can cause allergies or asthma in some people.

Some machines also clean smoke and other chemicals. These machines can be small units for a home. They can also be huge units for hospitals or factories. Using them helps make indoor air much safer to breathe.

There are two main ways these machines work. Active purifiers release charged ions into the air. These ions make pollutants stick to surfaces. Passive purifiers use filters to catch particles instead. Passive machines are often more efficient. They trap the dust and keep it inside the filter.

This means the dirt is permanently removed from the air.

One very famous tool is the HEPA filter. HEPA stands for high-efficiency particulate air. These filters can catch 99.97 percent of tiny particles. They are great at catching particles that are 0.3 micrometers big.

Some systems use UVGI, which uses ultraviolet light to kill germs. Other machines use activated carbon to soak up chemicals. This carbon works by turning gases into solids.

People have been trying to clean air for a long time. In 1830, Charles Anthony Deane made a copper helmet for breathing. In the 1860s, John Stenhouse used wood charcoal to clean air. He created the first practical respirator. Later, John Tyndall made a respirator for firemen in 1871. In the 1940s, the United States used HEPA filters for the Manhattan Project. In 1963, brothers in Germany sold the first HEPA filter for homes.

Air purifiers help in many different places today. In 2020, experts suggested using them in schools to help reduce COVID-19. In hospitals, testing showed that some filters can eliminate airborne viruses. This helps stop infections from spreading between patients.

Some modern machines even use light to help clean bacteria. This shows how much science can help keep us healthy.

An air purifier is a device designed to remove contaminants from indoor air. These machines improve air quality by capturing particles that can harm human health. People often use them to manage allergies or asthma. They also help reduce second-hand tobacco smoke.

Purifiers can be small, stand-alone units for homes. They can also be large systems attached to air handler units (AHUs) or HVAC systems. These larger units serve medical, industrial, and commercial buildings. In some industries, they remove impurities from air before it is processed.

There are two primary categories of air purification technology: active and passive. Active purifiers release negatively charged ions into the air. These ions cause pollutants to stick to surfaces. Passive purifiers use physical filters to remove pollutants. Passive units are generally more efficient. This is because they permanently remove dust and particulate matter from the air. The particles are trapped and collected inside the filter material.

Filtration is one of the most common passive methods. This process uses size exclusion to trap airborne particles. Air is forced through a filter, and particles are physically captured. High-efficiency particulate air (HEPA) filters are a standard in this field. They remove at least 99.97% of particles that are 0.3 micrometers in size.

In very dusty areas, a prefilter may be used. This conventional filter removes larger, coarse impurities first. This prevents the HEPA filter from needing replacement too quickly. HEPA filters are safe because they do not generate ozone or other harmful byproducts.

Other advanced technologies use light or chemicals to clean the air. Ultraviolet germicidal irradiation (UVGI) uses UV lamps to sterilize air. This is often used in forced air systems to kill microorganisms. Another method uses activated carbon. This is a porous material that can adsorb volatile organic compounds (VOCs). Adsorption allows the carbon to change contaminants from a gaseous phase to a solid phase.

Photocatalytic oxidation (PCO) is an emerging technology. It uses short-wave ultraviolet light (UVC) to energize a catalyst, such as titanium dioxide (TiO2). This process can oxidize and degrade organic contaminants. A related, more efficient version is called photoelectrochemical oxidation (PECO). PECO uses electrochemical interactions to improve efficiency using lower-energy UVA radiation.

Polarized-media electronic air cleaners combine electronic and mechanical methods. These cleaners use a safe 24-volt DC voltage to create an electric field. As particles pass through this field, they are re-oriented. This helps them adhere to a disposable fiber media pad. This technology is non-ionizing, so it does not produce ozone. These systems are useful because their efficiency can increase as they load with particles.

The history of air purification began long before modern HEPA filters. In 1830, Charles Anthony Deane patented a copper helmet with a leather hose. In the 1860s, John Stenhouse used wood charcoal to create the first practical respirator. Later, in 1871, physicist John Tyndall invented a respirator for firemen. HEPA filters were commercialized in the 1950s. They were first used in the 1940s during the United States' Manhattan Project to control radioactive contaminants. The first residential HEPA filter was sold in 1963 by brothers Manfred and Klaus Hammes in Germany.

Modern air purification has significant health implications. Allergens like pollen, mold spores, and pet dander can trigger respiratory issues. In 2020, Joseph Allen from Harvard recommended HEPA filters in classrooms to reduce COVID-19 transmission. Real-life testing in hospital wards showed that portable HEPA/UV filters could eliminate airborne SARS-CoV-2.

These devices also reduced other bacteria and fungal bioaerosols. This helps prevent nosocomial infections, which are infections acquired within a hospital setting. While effectiveness is high, compliance can change as other restrictions, like masking, are reduced.