Did you know that indoor air is often more polluted than outdoor air? The U.S. Environmental Protection Agency (EPA) found that humans can often be exposed to air pollutants two to five times more indoors than outdoor pollution levels.
Pollutants such as dust, pet dander, pollen, mold, fungi, bacteria, and viruses contribute to poor air quality. Poor air quality can lead to short-term health effects such as coughing, eye irritation, and headaches. Poor air quality can also cause and lead to long-term harmful health effects such as asthma and other respiratory diseases. It can even affect the cardiovascular system.
So what is the best way to ensure that the air in your home is as healthy and clean as possible?
An air purifier is a machine with an air filter that removes fine particles and gaseous pollutants from indoor air to clean the air and create a healthier environment.
There are different types of air purification devices. However, they generally follow similar principles, using science and mechanical processes to remove air particles from indoor environments to create better air quality.
There are many different types of air filters, all with their own benefits and technologies. The right method for you depends on what type of pollutants and particles you want to remove from your environment.
It’s worth doing your research to make sure the model you buy is up to the task. Don’t buy a filter that only removes larger particles from the environment when you want to remove fine dust particles.
What are the basic functions of an air purifier?
An air purification unit generally consists of a motor, a fan, and an air filter. The motor and fan circulate the air, while the filter removes pollutants from the air as it passes through the machine. In addition, some air filters use negative ion generators to attract airborne particles and successfully remove them from the atmosphere.
What technologies are used for air filtration?
There are a variety of technologies that can be used to filter and deliver purified air. Here are the most popular methods:
Mechanical filtration using fiber media
The most widely used air purification technology removes particulate pollutants from the air, such as dust, dust mites, and pollen, by trapping them in a fiber filter for removal. Mechanical air filters cover any type of dry media filter, including disposable air filters often used by HVAC systems and HEPA equipment.
Mechanical filters work on two principles. In primary air filtration, dust is attached to the filter. The secondary process is to remove particles from the filter media. As dust builds up on the filter material, the filter becomes less efficient, so it is critical to keep the filter clean for optimal contaminant removal.
HEPA filters, or high-efficiency particulate air filters, are the most effective type of mechanical air filter, removing at least 99.95% of airborne particles from the environment.
Electrostatic Precipitation
These filters work using an electromagnetic process, passing contaminated air through an ionizing section to draw out airborne contaminants and capture them for removal. They work similarly to magnets. This process adds a charge to particles as positive and negative charges attract each other, and the particles are then captured and stored on oppositely charged plates for disposal. With electrostatic air filters, there is no filter media, but rather charged plates.
Electrostatic air filters are effective at capturing both large and fine particles. This may be the most effective filter if you are looking to remove fine contaminants, as the fine particles will receive enough of a static charge to be collected on the plates. Other types of filters may miss these fine particles.
Electrostatic air purifiers do not use the MERV (Minimum Efficiency Reporting Value) scale because they are not classified as mechanical air filters. Instead, they are measured by arrestment rate (the ability to remove synthetic dust), with most filters rated above 99.95%.
It is important to note that arrestment rate is not the same as efficiency. It simply measures the percentage of dust weight (in grams) that the filter can hold before it becomes loaded.
Adsorption
Not all air pollutants are particles. There are also gaseous pollutants, such as molecules produced during combustion, including gas stoves, car exhaust, and tobacco smoke. The air can also contain volatile organic compounds (VOCs), such as cleaning fluids, adhesives, paints, and varnishes. These molecules require specialized air filters to remove gaseous pollutants.
Adsorption is an exothermic (heat-releasing) process that uses materials with high internal surface area, suitable pore structure, and surface chemistry to remove gaseous molecules from the air. Activated carbon is the most commonly used substance in air filtration.
However, it is important to note that this process does not remove particles from the air; it simply reduces the levels of gases and odors. Therefore, filters using adsorber systems are often used in conjunction with other filtration methods to provide clean air and prevent carbon or other media from becoming overloaded with excess dust.
Photocatalysis
Photocatalysis is another method for removing gaseous pollutants. Instead of using an adsorbent media, photocatalytic air purifiers use ultraviolet light and a catalyst, usually titanium dioxide, to clean the air.
The process uses ultraviolet light to power the catalyst, which then targets harmful pollutants and effectively destroys them. While this may seem cleaner and safer than methods that capture pollutants for later disposal, photocatalytic air purifiers produce trace amounts of ozone, a toxic air pollutant that can cause inflammation and damage lung tissue.
Plasma
The plasma method uses a high-voltage electrical current to ionize the air and charge the molecules in the air. This creates reactive free radicals that then attack and destroy pollutants in the air.
However, like photocatalysis, the process produces potentially harmful byproducts such as ozone and nitrogen oxides. Additionally, ionizers generally only work properly when used with a different type of air filter, such as a mechanical filter, to remove particles from the air.