Do HEPA Filters Remove VOC’s?

HEPA filters are the number one choice for air purification across most Industries.

Their capacity to capture particulates as small as .3 microns make them extremely efficient at removing pollutants and improving indoor air quality.

But what about pollutants that are smaller then .3 microns?

Do HEPA Filters Remove VOCs?

The answer is no. By definition, VOCs are gas type particles that are smaller than .3 microns. A carbon filter used in conjunction with a HEPA filter is the standard for removing vocs.

do hepa filters remove vocs?

Vocs are usually described as the chemical or gas air pollution that come from building Products such as adhesives, paints, acrylics, and so forth.

Crafting products, tobacco carcinogens, cleaning products also fall under this category.

Formaldehyde, generally agreed to be one of the toughest volatile organic compounds to remove, can in fact be absorbed by a carbon filter.

That point alone puts carbon filters ahead of the game and places them as the top technology for reducing volatile organic compounds (VOCs)

Benzene and naphthalene are also adsorbed easily with the use of carbon filters.

But the problem with HEPA and carbon filters being the primary Technologies in these arenas is that,

Air purifier consumers have to unwittingly sign up for the filter of the Month Club in order to keep their machines working properly.

That and the fact that you are limited to using them and a small area primarily.

This makes the use of HEPA and Carbon filters in large buildings with multiple rooms like hospitals and schools very expensive to say the least.

Regardless of their limitations they  remain the industry standard. And Industry standard can sometimes be a barrier that is hard to penetrate.

Especially when the experts have their own HEPA air purifiers that they are touting.

But despite the political Riff Raff, other air purifying technologies are edging their way up because of their capacity to take on large areas without the need of multiple replacement filters.

In duct air purification or HVAC (central heat and air) air purification is the obvious wave of the future and one that HEPA is having a hard time keeping up with.

When it comes to improving air quality throughout multiple rooms and reducing the spread of germs over a large area,

Placing plasma air purifiers in the ductwork not only removes pollution at the source inside the unit,

They also removes the pollution being recirculated through the unit and redistributed back into the air you breathe.

This is a win-win situation and one that HEPA or carbon cannot tackle.

Some will say that you just need to use HEPA filters in your HVAC system and that you only need choose the proper Merv rating for allergens.

The problem is that air Handlers are made for the Air to flow freely

and using a very dense filter like HEPA combined with carbon will place an enormous

amount of strain on the unit setting yourself up for mechanical breakdowns.

That fact and the fact that HEPA filters are much more expensive then the typical air filter,

Shine a large lamp on the inefficiency of HEPA in large multiple room situations.

Using carbon filters to reduce Gas by products in the HVAC suffers from the same scenario.

They restrict airflow through the system and introduce the need for a second filter because HEPA filters cannot absorb gases.

The four Technologies taking on this problem with success are:

  • Ultraviolet sterilization
  • Photocatalytic oxidation
  • Cold plasma
  • HVAC dehumidifiers

HVAC Indoor Air Quality

One of the main problems with controlling air quality in large areas with multiple rooms like schools is that the HVAC that is in place to control the climate in the building is also one of the main contributors of bad air quality itself.

How so?

a.  The environment inside the HVAC housing is not only dark, it is moist. The ideal breeding ground for mold.

This means that without a way of controlling it, each and every time your air handler kicks on,

it is actually distributing mold spores throughout your business or living space.

b.  Outdoor air is distributed through the unit

and depending on the area and  environment you’re in, your inside air can be affected by fuel emissions, industrial smog, etc.

c. Air inside the building is also introduced into the system and becomes part of the recirculating cycle.

That means if one room is dedicated to printing,
the vocs contained in the ink as well as the ozone being sparked when the printers are running
are put back into the Airstream and distributed throughout the whole building for everyone to enjoy.

1. Ultraviolet sterilization works by placing UV lights above the condensers and the drip pans in the plenum of the HVAC.
The ideal is that ultraviolet light kills anything that it is targeted on.
Many industries use UV as a way of sterilizing fish tanks, surgical equipment, and many others.

When I think of UV lamps, they remind me of the barber shop that my father took me to as a kid. I would see that jar that had that blue light in it to sterilize the combs and scissors while I would sit there and get my hair buzzed.

This is the same concept as using UV in your HVAC system.
Placing UV lamps in the areas the drip pan where mold is forming will help kill the mold spores before they ever have a chance to enter into your ambient air. (the air you were breathing).

2. A step up from UV lamps is photocatalytic oxidation.

Photocatalytic oxidation or PCO also uses ultraviolet light but it does so in a different manner.

Instead of focusing on what you were trying to sterilize, the focus on a titanium catalyst.

Ultraviolet light combined with a titanium catalyst creates a reaction of hydroperoxide ions.

Hydroperoxide is the gas form of hydrogen peroxide,

Hydrogen peroxide is the stuff that you pour on a wound to clean it before you put the triple antibiotic on it.

So in a manner of speaking, this technology is like pouring hydrogen peroxide on every infectant in your air  handlers vent work.

These air purifiers are a considerable improvement on UV alone.

Photocatalytic oxidation is also very effective at removing mold spores.

Benefits include filterless air purification and the capacity to cover large areas. Because PCO uses ultraviolet light it does require the annual replacement of the module.

There is a downside though. And though it is not a huge one considering these are purifiers are meant to be placed inside of the ductwork, PCO air purifiers create small amount of ozone in the process.

Ozone is really not an issue here because it dissipates very quickly and will never have a chance to enter into the breathing space.

But unfortunately the mention of the word ozone is enough to deter a large amount of the population from using this technology.

A Pity.

3.  Atmospheric Cold plasma is it technology that works on the molecular level.

It is another form of Ionic air purifier that has an advantage over UV and PCO because

a. it doesn’t introduce ozone or formaldehyde into the airstream.

b. It is extremely effective at reducing microscopic air pollutants like bacteria and mold spores.


Cold Plasma works by dividing ions into negative and positive. When the split ions spring back together because of polarity they capture any pollutants in the air in the process.

This technology is used to sterilize food and water as well as a dental tool to prevent decay in the teeth just to name a couple.

Because of its ability to reduce any type of VOC including formaldehyde, it is one of the best unheard of air purification methods available.

It is also a very inexpensive type of air purifier to run. It takes very little electricity and requires zero replacement filters.

4.  HVAC dehumidifiers or whole house dehumidifiers or not a full solution for reducing indoor air pollution being circulated through the HVAC

but they can help considerably with controlling air pollution and reducing wear and tear on your air moving system.

a. By reducing the moisture in your system,

you are eliminating one of the primary ingredients production of mold.

Dust mites also need a lot of humidity you to flourish.

b. Humidity causes your system to run over time to cool off a room.

By removing the humidity in the system and in your building,

you are giving your HVAC system a much easier time to work properly and reducing the need for repairs to the system.


HEPA and carbon filters maybe the industry standard for reducing air pollution

but they are not the only solution and they’re definitely not the less expensive solution especially in large buildings with multiple rooms.

In duct air purification the uses Technologies like cold plasma and photocatalytic oxidation

are as effective and even better in many cases

and are much less expensive to run and keep up with replacement cost and wear and tear on your HVAC system.

Can HEPA and carbon be used in conjunction with other in duct Technologies ?

Of course.

Why shouldn’t you have a carbon filter in your printing room?

also this: ionizer in air purifier

Published by

Dennis Reed

Dennis Reed Owner and Author @