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FAQ: Air Purifier Filters

While most people know about the replacement air filters for their heating and cooling system there are many questions that come up related to air purifier filters since you are looking for it to do much more.

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Top Questions

Based on questions from customers over the past few years we assembled this list of most common questions.

What is a HEPA air purifier filter?

HEPA filters were first developed by the US government in the 1940’s as a way to create an effective gas mask. While there have been innovations in the past 75 years the principles of how a HEPA filter works is the same. A HEPA filter removes 99.97% or more of particles that are sized 0.3 microns and larger by capturing them in the fibers. Over time as the filter becomes dirty the HEPA air purifier filter will perform at higher efficiencies.

The HEPA filter is the core technology of HEPA air purifiers. If you are sensitive to allergies or dust, have a condition like COPD or asthma you will want to use a HEPA filter and in most cases you get what you pay for.

Can a HEPA filter remove smoke and cigarette odors?

Cigarette smoke is made up of a variety of particulates and gases. A HEPA filter will remove the smoke particulates however smoke odors are tiny gases and will pass through the HEPA fibers.

Many people assess the performance of smoke removal based on odor removal and a HEPA filter alone will not accomplish this. What is needed is a carbon filter to adsorb the smoke gases. The carbon will not remove the smoke particulates so to effectively remove smoke it requires a combination of a HEPA filter and a carbon filter.

For best results for odors you will want more and higher quality carbon. The top end air purifier we offer is the mod with a HEPA filter and carbon-activated filter.

What is the difference between a HEPA air purifier filter and the low cost store filters?

The low cost air filters you will find in the big box stores are designed to keep large dust particles from accumulating and damaging your HVAC system. They are not designed to improve your indoor air quality.

Recently there have been some higher efficient store filters that promise to address your allergy issues however the problem is that with a higher efficiency in many cases they create a higher air flow resistance than what your HVAC system is designed to handle. This adds stress to the HVAC system as this filter becomes dirty and likely will cause it to run more to heat or cool your home.

A HEPA air purifier filter has the highest efficiencies so it can remove the smallest, most dangerous particles. The tiniest of particles stay suspended in the air the longest and are the one’s that you will breathe deep into your lungs. A low cost store air filter is not designed to capture these tiny particles.

To see a listing of filter ratings, visit

The low cost store air filters are in the MERV 2-8 range whereas a HEPA filter is in the MERV 16-18 range.

What are the advantages of a HEPA filter?

The key advantages of a HEPA filter are that they perform at the highest level and are the safest. You are buying an air purifier to clean the air and no technology is better than HEPA since no other technology can effectively remove the tiniest, most dangerous particulates from the air. HEPA filters also are the safest as they introduce no pollution into your room such as ozone which can be generated with other technologies.

To learn more see our comparison of filter-less air purifiers versus HEPA air purifiers.

How does a carbon filter work?

Activated carbon contains many crevices that act as a sponge to adsorb gases such as smoke odors. Carbon becomes activated through a baking process and then turns into a molecular gas sponge.

There are many factors that determine how effective a carbon filter will be such as the quality of the carbon, the carbon surface area, the contact time for carbon to adsorb the gases and the molecular weight of the gases to be removed.

Activated carbon is very effective for higher molecular weight gases however for low molecular weight gases such as formaldehyde an additional media is needed.

How are air purifier filters rated?

Air filters in the US are rated based on a MERV rating scale.

HEPA air purifier filters have the highest rating at MERV 16-18 and are designed for the highest level of air cleaning in a specific room.

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