How Do Air Purifiers Work: Complete Guide

There are more reasons than ever to be mindful about air quality. Climate change makes wildfires and high pollen counts more prevalent. Adjacent to that, we’re producing more pollutants. Plus, we’re spending more time indoors with our family and pets.

That’s why manufacturers produce air purifiers in all shapes and sizes, using a wide variety of technologies. However, regardless of the method, almost every air purifier works on the same principles. We’re going to go over what air purifiers are supposed to do and how they do it.

What Are Air Purifiers?

An air purifier is a device that draws in air and, as it passes through, removes particulates, then expels the air. In theory, air purifiers should remove substances that irritate us or harm our health. These substances can range from pollen, volatile organic compounds (VOCs), to viruses.

People benefit from owning an air purifier if they are allergic to pet dander or pollen or want to reduce odors in their homes. Subsequently, relief from malodors and allergy triggers can improve your health, especially your sleep.

How Air Purifiers Work

Air purifiers work on three basic principles: air intake, filtration, and clean air delivery.

Step 1: Air Purifier Pulls Air In

Generally, an air purifier uses a fan or static charge to draw in air from the surrounding area. The rate at which they can draw in air is often denoted as CFM or cubic feet per minute in the US.

Step 2: Air passes through filters

Most air purifiers have a physical filter made from substances like fiberglass or foam. The filter is porous with holes big enough for air to pass through, but small enough to capture particulates.

Some air purifiers have additional methods like using static or even plasma to deal with fine particles or microorganisms.

Step 3: Clean air comes out

After the air passes through a filter, it is released back into the room. It usually gets blown into the room via a fan and usually straight up, though there are a select few models that blow sideways. The volume of air a purifier can release is often called the clean air delivery rate or CADR.

Types of Air Purification Technologies

Mechanical Filter (HEPA)

This is the type of filter that captures particulates by being porous enough to allow air to pass through, but not particulates. The most popular type of mechanical filter is HEPA. Mechanical filters have the most variability.

On the very high end, you have filters like HEPA-14, which is medical grade and can remove pathogens from the air. On the low end, mechanical filters can only remove dust. That large spread is the biggest pro and con of mechanical filters.

Activated Carbon Filters

Carbon filters are usually mechanical filters with carbon injected into the medium. Activated carbon is created by exposing carbon to heated gases or chemicals to increase its surface area while reducing the volume of the pores on its surface. Activated carbon is good at removing odors. However, filters with carbon injected tend to be more expensive and not last as long as regular mechanical filters.

Electrostatic

Ionizers zap the air passing through them with negative ions. Then a positively charged plate attracts the particulates.

Some ionizers just charge the surrounding area to cause particulates to fall out of the air. Because they don’t have a fan, electrostatic air purifiers can be very quiet. However, they are known to produce ozone, which can irritate people, especially those with asthma.  

UV-C light

UV, in its various incarnations, is used to kill germs by denaturing the genetic material they need to survive. Based on the research we’ve read, UV-C lights have limited effectiveness. UV-C lights require a lot of extra power to function, and most airborne pathogens are at least somewhat resistant to the UV rays.

How Much Electricity Does an Air Purifier Use

Energy Star states that the average air purifier uses 450 kWh per year. But this is a little off balance because the calculator includes 35-kilo units with built-in humidifiers to personal units that sit on your desk.

If you include just models meant for a person or a room, the number is closer to 150-250 kWh per year, or roughly one-third that of a moderately sized refrigerator. An air purifier uses even less energy if you get a model that has a sensor that activates the fan if there is a decrease in air quality or if you only use it during part of the year.

Also, keep in mind that air purifiers that use electrostatic or UV-C technology tend to use more power.  

Are Air Purifiers Effective?

Air purifiers are highly effective if you purchase one that suits your needs. For example:

• If you’re looking to cut down on allergens like pollen or pet dander, an air purifier with a HEPA filter will be effective.
• If you need one that helps reduce odors, one with a carbon filter will be better.
• Electrostatic filters are great for fine particles, but won’t do much good against VOCs.

You also need to make sure the unit you’re getting is the correct size for your situation. Purchasing an air purifier meant to sit on your desk will not cut down on your allergies if you expect it to clean a whole room.

Finally, you need to make sure to adjust your expectations. Air purifiers don’t remove carbon dioxide from the air, nor do they produce oxygen. They can reduce airborne illnesses, but only if you purchase one with a medical-grade filter. Also, since you probably don’t live in a hermetically sealed room, they cannot remove 100 percent of all pollutants and particulates.

You can maximize the effectiveness of your air purifier if you do things like vacuum regularly and keep your pets clean.

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