How Do Air Purifiers Work? Answers From a Phoenix Tech

An air purifier (sometimes called an air “cleaner” or “scrubber”) is a device that removes various contaminants from the air. The goal of an air purifier is to reduce the number of pollutants in your home’s air to make the air healthier to breathe.

Of course, that’s just a broad definition. Air purifiers come in various models and designs, so they each have different ways of purifying your home’s air.

The 4 most common types of air purifiers include:

1. High-MERV or HEPA air filter
2. Activated carbon filter
3. Electronic air cleaner
4. UV germicidal lights

We’ll explain how these air purifiers work in more detail below.

The effectiveness of an air filter’s ability to catch pollutants is measured by MERV (minimum efficiency reporting value), which is expressed as a number that ranges from 1 to 16. Air filters with higher MERVs can catch a higher percentage of airborne pollutants.

Every HVAC system has an air filter, but the standard air filters that most homeowners use typically have lower MERVs (1–4). Compared to these standard air filters, high-MERV filters (10+) are thicker and denser, which makes it harder for pollutants to pass through the air filter.

One type of high-MERV air filter is called a HEPA (high-efficiency particulate air) filter. A HEPA air filter is a more advanced filter made of interlaced glass fibers that act as a maze, trapping indoor air pollutants so they don’t circulate throughout your home.

A HEPA air filter is especially effective at removing contaminants such as:

• Dust
• Pollen
• Mold
• Bacteria

Typically, a high-MERV or HEPA filter isn’t something you can install yourself. Because these advanced filters are larger than standard filters, an HVAC professional may need to make modifications to your home’s return ductwork in order to accommodate the new air filter.

Activated carbon filters consist of packets of carbon that have been treated (“activated”) with oxygen, which makes the carbon especially porous. As air passes over the porous carbon packets, the airborne pollutants become attached to the carbon through a chemical process called adsorption.

The adsorption process in activated carbon filters is especially effective at removing odors and gases from indoor air. Most activated carbon filters are installed in the return section of your ductwork, often combined with an advanced air filter as a double-defense against indoor air pollution.

A whole-house electronic air cleaner (also called an “ionizer”) is a device that’s installed in the ductwork of your home’s HVAC system. Electronic air cleaners use a pre-filter to catch large particles. Smaller particles that make it past the first filter go past by an ionizer, which emits electrically-charged molecules into the air.

Here’s where things get a little science-y: The electrically-charged molecules emitted by the purifier bond with oppositely-charged pollutants in the air. This causes the pollutant molecules to get heavy and attach themselves to collection plates inside the ionizer. The weighed-down molecules will remain on the plates, which can be cleaned periodically.

UV germicidal lights consist of a lamp with a bulb that emits powerful ultraviolet light. The UV light neutralizes airborne contaminants that pass through the UV light rays.

UV air purifiers are often installed in the air handler of your HVAC system, where it’s common to find mold growth (the air handler is a naturally dark and damp place.) Besides preventing mold buildup in your air handler, the air that passes through your AC will also be healthier because the UV light will neutralize airborne pollutants.

Although UV light is harmful to humans if they come into direct contact with it, a UV-light air purifier poses no health risks if it is installed correctly. That’s because the UV light purifier is installed in an enclosed space inside your air conditioner, which is a place only trained professionals will ever access.