How Do Air Purifiers Work?

People who suffer from allergies and asthma know how important it is to have clean air. This can be tricky with today’s environmental issues. Between pollution and rising levels of pollen and other allergens, finding a clean patch of air to breathe can be a real chore. It is no wonder that so many people are trying to improve the air in their homes and offices. One way to do this is to use air purifiers.

Air purifiers clean the air of impurities and airborne irritants. They can filter out smoke, mold, pollen, pet dander, and some viruses which can irritate and damage your lungs and immune system. These days, with all of the chemicals and materials used in homes, plus the addition of pets, a home’s air can contain more pollutants than the outside air. Using air filters can reduce the amount of irritants and toxins in the air. But how? How do air purifiers work? What are some types of air purifiers on the market today? Let’s review them.

Types of Air Purifiers

There are several types of air purifiers and each one works using different methods. The different types are air filters, electric static purifiers, ionic purifiers, ozone generators, absorbant purifiers, and UV light purifiers.

Air Filters


This type of air purifier uses a filter to pass the air through and remove particles and pollutants. These filters are usually found in a house’s central air system. There is a filter placed between the furnace or unit and the ductwork that runs through the rest of the house. Not only does this remove contaminants from the air, it also prevents damage to the furnace due to the build-up of dirt. You can also put a filter in the return duct that flows back into the unit. Pleated filters are the best for air systems. The drawback to only using the filter in your air conditioning system is that it only stops particles that are 10 microns or larger. A micron is the unit of measure for air particles. You can’t see anything smaller than 10 microns so most bacteria and pollutants go unnoticed.

For a better filtering system, you’d better use an air purifier. Using the same filtering principles, there are air purifiers that use various filters to clean the surrounding air. The finer the filter, the smaller the particles it is able to trap. There is a standard benchmark for air filters set by the High Efficiency Particulate Air (HEPA) filters. These filters are guaranteed to trap 99.97% of airborne particles larger than 0.3 microns. HEPA filters can remove very small allergens such as dust, smoke, chemicals, asbestos, pollen, and pet dander. The more times the air passes through the HEPA filter, the cleaner the air is that comes out.

Electric Static Purifiers

Another type of purifier is one that relies on electrical static to trap particles.

It does this by one of two methods. In the first method, electrostatic purifiers are able to draw air in using a fan and then charge the particles with a series of electrical wires. Inside are several plates that carry the opposite charge. These plates attract the contaminants as they pass and cause them to stick to the plates. The second method involves the air passing through synthetic fibers that cause a static charge similar to rubbing your feet on the carpet. Particles then stick to the fiber. In either method, only clean air passes out through the purifier. The benefit of electric static purifiers is that you don’t have to buy new filters periodically and hassle with changing them out.

Ionic Purifiers

Ionic purifiers use a process called corona discharge which is a small but intense electrical field. The corona discharge creates charged molecules called ions. As air passes through the purifier, particles will stick to ions, causing them to get heavier and thus can’t pass through the filter.  Particles such as dust are more likely to be ionized because they are larger and easier for the ions to stick to. Ionic purifiers are only effective against certain particles and pollutants. They have not been very effective against trapping gasses, chemicals, or odors. In some cases, the ionozed particles are released back into the air where they settle on furnishings.

Ozone Generators

An ozone generator works much like an ionizing purifier. An ozone generator uses elctricity to convert oxygen and turn it into ozone.

These types of purifiers are advertised to deodorize and disinfect the air. There is also some claim that there are health benefits from ozone purifiers. However, this is a point that is beign debated. Ozone is also known to be a toxic gas and there have been some reported health problems from people using an ozone purifier. Ozone at ground level can act as an irritant to your lungs. Ozone also oxidizes metals and causes corrosion.


There are some purifiers that use an absorbant matrial to clean the air of odors, chemicals, and pollutants. The most common adsorbent is activated charcoal. Charcoal is very porous and can easilly trap other particles. Larger particles are simply stuck in the many pores in the charcoal while an electrostatic charge draws smaller particles into the pores. The drawback to this type of purifier is that there are some chemicals that react to charcoal.

UV Light

This last type of air purifier is different from the others because it does not use an electrical charge to attract particles (which can help you lower your electric bill). These air purifiers use a UV light that bathes the air as it passes through the purifier. Ultraviolet light can render many micro-organisms such as bacteria and active mold hamrless. By pushing air through the UV light, it can eliminate many viruses and diseases.