The Wide World of Filtration

In the movie “My Big Fat Greek Wedding”, the father of the bride is known to use Windex to clean anything and everything. I’m sure he would solve indoor air quality (IAQ) problems by just spraying more Windex!  (Shhh, don’t tell him that he’s adding volatile organic compounds to the air!)  In the search for a panacea for all IAQ problems, many people try to clean anything and everything with filtration.

In the coming weeks, I will be adding some blog posts about filtration.  But first I want to quickly show you that “filtration” can mean one of many things.  Look at all the different categories and sub-categories of filters:

1. Particulate Filtration

A. Fibrous Media Filters

i. Viscous Impingement (e.g. spun fiberglass)

ii. Dry Media (e.g. pleated filters, HEPA filters)

B. Electronic Air Cleaners

i. Ionizers

ii. Electrostatic Precipitators

2. Gas Phase Filtration

A. Adsorption (e.g. activated carbon)

B. Chemisorption

C. Photocatalytic Oxidation

D. Ozone

Each of these categories has its advantages and disadvantages over the others.  Some remove particles, some remove gases.  Some are expensive, some are economical.  Some are efficient, some are inefficient.  In other words, we cannot make broad brush statements about filtration because it encompasses so many different technologies.

In fact, I like to use the term “air cleaning” in place of filtration because I think it more accurately describes all the processes above.  Enjoy the weekend… and don’t overdo the Windex, ok?

By Ian Cull

I'm I.A.N. the Indoor Air Nerd. I'm a speaker and consultant on indoor air quality issues. To learn more about me, click "about" at the top of this page.

3 replies on “The Wide World of Filtration”

Home owner. Bought a house that was being remodeled and then abandoned …with no hvac etc run for many months. Now there is visible mold in the basement, and in the kitchen area and perhaps other areas. I plan to remodel, what professional do I look for, what credentials, any tips. Should sub flooring be removed if there is visible mold on it or is it scrubbable and treatable?

New HVAC systems planned. What filtration would be our best plan … perhaps we do fibrous and electronic together. Any stand out systems.

I have young children. If I am in the wrong site, refer me. I don’t want to be a pain but want to accurate in my decisions. Regards. L

Here is the short answer: clean anything that can be cleaned (mostly hard surfaces). Throw away anything that can’t be cleaned well (e.g. drywall, upholstered surfaces). Wood surfaces will likely need to be roughed with sandpaper or wirebrushes (or soda blasting, or dry ice blasting).

As for your new HVAC design, humidity control is probably more important than filtration.

I would recommend hiring a consultant who can give you solid advice on the mold remediation and HVAC systems. Where are you located? Perhaps I can recommend one of my past students depending on where you live.


Is there an opinion about the dry ice blasting versus the wipe down approach? Is it appropriate to have baseline and post remediation air quality testing and by whom? Appreciate a solid resource to be certain we have truely remediated and watch my dime. The remediation quotes are wildly varied both in intervention and cost. HVAC planning is mostly guess work. Thanks. L

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