The Different Types of Air Purifiers

2. Filterless Air Purifiers

Filterless air purifiers do not use any type of filter or filtration system. Instead, they rely on different types of technologies to clean the air. Often, these technologies are used in conjunction with filtered air purifiers to increase their efficiency. They are also highly efficient on their own, though, and users have found them easier to maintain because filter replacements are no longer an issue.

Air Ionizers

An air ionizer is a type of air purifier that cleans the air with the use of negative or positive ions. It releases a very high concentration of these ions which attach themselves to air pollutants that are usually neutral so that they either have a negative or positive charge. Once charged, they become attracted to surfaces or other pollutants with the opposite charge. As they stick to each other, they become too heavy to remain airborne and settle on the floor or the walls to be cleaned or vacuumed later. Ionizers are very effective at removing common household air pollutants but often have trouble removing smoke, volatile organic compounds, and other odors. Another drawback is that ionizers tend to produce a small amount of ozone while they’re running. Ozone has been known to cause chest pain, coughing, and throat irritation even at low levels.

Electrostatic Precipitator/Electrostatic Air Cleaners

An electrostatic precipitator functions almost the same way as an air ionizer except that it has electrically charged plates that are able to collect air pollutants. For it to remain effective, these plates need to be cleaned regularly. If these collection plates are left to accumulate large amounts of particles, they may sometimes bond so tightly to the metal plates that vigorous washing and scrubbing may be needed to completely clean them. This is one of the downsides to owning an electrostatic air cleaner. Aside from that, it also produces small amounts of ozone and nitrogen oxide.

Ozone Generators

Ozone generators are popular — albeit very controversial — air purifiers that are used for cleaning the air. Ozone released by ozone generators have three oxygen atoms, one of which can remove itself and then reattach itself to pollutants. A chemical reaction then occurs to render these pollutants harmless. Unfortunately, studies have shown that the substances produced by the chemical reaction of ozone with pollutants can actually be more harmful than the pollutants themselves. In addition, several studies have already debunked the effectiveness of ozone generators. This is because, in order for ozone to effectively remove pollutants and kill bacteria and viruses, it has to release a higher concentration than the limitations set by the government. Furthermore, the use of ozone generators in small, closed spaces is dangerous since ozone in high concentrations can cause several health problems and trigger asthma attacks. Needless to say, it would be better to steer clear of ozone generators.

Thermodynamic Sterilization

Air purifiers that use thermodynamic sterilization (TSS) to clean the air are also rapidly gaining popularity as they require little maintenance, don’t make any noise, and don’t produce any harmful substances while in use. These models work by allowing polluted air to pass through the air purifier by the process of convection. The air passes through the air purifier’s ceramic core with micro capillaries which are heated up to 200°C. This process claims to incinerate 99% of bacteria, viruses, dust mites, mold, and fungus spores. It is important to know that air purifiers that use TSS do not actually remove or trap any airborne particles. Rather, they are rendered harmless due to the heat treatment. In addition, air purifiers that use TSS take longer to clean the air since no suction fans are used. However, one advantage of TSS in air purifiers is that they’re able to significantly reduce ozone levels in the environment.

Ultraviolet Germicidal Irradiation (UVGI)

Ultraviolet germicidal lights have long been used to eliminate microorganisms such as bacteria, viruses, molds, and fungi. They work by damaging the genetic material of these microorganisms, rendering them unable to reproduce and completely eliminating them in the process. This type of air purification technology is most commonly found in hospitals and laboratories where a sanitary environment is crucial. The main problem with UV light is that it is also harmful to plastics, human skin, and eyes, making it impossible to be used with people in the vicinity. Recent developments in air purifying technology, however, have allowed UVGI lights to be used in overhead ceiling lights in a manner that causes air near the ceiling to be irradiated. The systems are designed so very little of the UV light penetrates into the occupied portion of the room. Like with TSS technology, UVGI also does not target the removal particles. There are several factors that will affect the effectiveness of UVGI systems such as the intensity of the UV light, the duration of irradiation, humidity, the target organism, and other factors. Unlike ionizers and TSS air purifiers that require little to no maintenance, UVGI cleaners need their UV light bulbs replaced yearly which may be costly.

Photocatalytic Oxidation (PCO) Cleaners

Another emerging technology in air purification is photocatalytic oxidation (PCO). PCO cleaners also use UV light to react with a catalyst (usually titanium dioxide or TiO2). The reaction is able to oxidize bacteria, viruses, mold, fungi, odors, and volatile organic compounds. Oxidation breaks the pollutants down into harmless carbon dioxide and water molecules, making the air more purified. PCO cleaners are excellent at removing gaseous air pollutants like odors and VOCs. However, like TSS and UVGI, PCO cleaners are not designed to trap or remove particulate pollutants. Their UV light bulbs also need to be replaced yearly. In addition, PCO cleaners often have high commercial costs.

Whole House Air Purifiers

Whole house air purifiers, or central air purifiers, are designed to work in conjunction with your HVAC system and run continuously to purify the air throughout your entire home. They tend to be very effective and noticeably improve the air quality in your house. They require less maintenance, have longer-lasting filters, and don’t need separate power as they instead simply working off of your existing HVAC system. Whole house air purifiers vary in the way they are connected to your HVAC system.

Here are the three main types of whole house air purifiers depending on how they are installed:

• Filter-based units – These are installed into your HVAC furnace systems and air intake points
• Duct-based units – These are installed directly into the air duct path, either before or after the air handler in your HVAC system
• Stand-alone units – These types of systems are installed in closets or attics, followed by installing additional air intake and exhaust into the home

Whole house air purifiers can cost thousands of dollars and would require an HVAC technician to have them installed. However, they’re ideal for those who aren’t keen on frequent cleaning and maintenance. Like air purifiers that use filters, whole house air purifiers also make use of filters to clean the air albeit at a much larger scale.

Some of the most commonly used whole house air filters include:

1. Mechanical Filters
   

   Mechanical filters physically trap the particles in the air as they circulate through your system, holding them in the filter and preventing them from being introduced into your home environment. There are two types of mechanical filters: flat filters, which are commonly used in residential furnaces and air conditioners to protect the buildup of unwanted materials in the HVAC equipment, and pleated filters, which increase the efficiency of flat filters by layering them to make airborne particulates easier to trap and remove.

   Examples of mechanical filters include pre-filters, HEPA filters, and carbon filters.

2. Electronic  Filters
   

   Electronic filters are very effective at removing very small particles and odors, but may be ineffective at removing larger particles. Therefore, they need to be used in conjunction with other filters to increase efficiency. Like with pleated filters, electronic filters also need to be professionally installed. The two main types of electronic filters include: electromagnetic filters, which use electrically charged wires to cause particles to gain a positive electrical charge which is then magnetically attracted to a collection plate, and ionic filters that give particles a negative charge and attract them to positively charged collectors.

3. Ultraviolet Light
   

   Like room air purifiers, whole house air purifiers also make use of UV light to take care of biological pollutants such as bacteria, viruses, mold, fungi, and dust mites. Ultraviolet air cleaners are often installed as add-ons to an electrostatic system.

4. Photocatalytic Oxidation
   

   Although not yet popular in the whole house air purifiers industry, some whole house air purifiers also make use of photocatalytic oxidation. With whole house air purifiers using this technology, it’s pretty much the same purification process: using UV light to react with a catalyst, different impurities oxidized and are rendered harmless. They’re excellent for removing a range of air pollutants including odors and VOCs. They’re virtually maintenance-free since there are no filters involved. However, the UV light bulb does need to be changed as needed.