This article discusses the most utilized ways to clean indoor air.  Al’s Plumbing, Heating & A/C, in Plano, Texas provides full-service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s Plumbing, Heating & A/C is near your home in Plano, TX; Allen, TX and Frisco, Texas.  We service all homes in southern Collin County, TX and Denton County, TX with no additional travel charge.

Al’s also provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally, we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard), and Coleman HVAC (same company as York HVAC).   Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience.

Click Here For Way To Lower Cooling Costs: 75 Ways To Lower Cooling & Heating Costs

The Most Utilized Ways To Clean Indoor Air 

1. A High MERV Rated Furnace Air Filter

dirty air filter on left. New air filter on right.

Image Source: CanStockPhoto

Shown: A New Furnace Filter (on right).  On The Left — A Badly Neglected Air Filter That Should Have Been Replaced Months Earlier.


MERV stands for Minimum Efficiency Reporting Value.  MERV ranges from 1 – 20.  MERV advises of the filter’s effectiveness at removing airborne particles of different sizes.  The higher the MERV — the more airborne particles it catches.  For Example: a MERV-13 filter catches 90% of particles that are 1-10 microns and larger — and 50% of particles less than 1 micron.  As Compared: A human hair ranges from 20 — 75 microns wide.

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fiberglass furnace filter

Image Source: ShutterStock

Shown: A Spun-Fiberglass Furnace Air Filter Protects The Furnace — It Doesn’t Clean Indoor Air


The higher the MERV rating — the better the filter will clean the air —  BUT, the higher the MERV — the more reduction of air flow through the furnace.  Plus, the higher the MERV — the more frequently the filter must be replaced.  If neglected — a high MERV filter will reduce airflow through the furnace to the extent the HVAC System can be damaged.

The furnace’s blower-fan is rated for only a specific amount of air flow reduction.  If you use much of the furnace’s air flow reduction capacity at the air filter — little remaining capacity  remains to move air through the HVAC System — and you’re unlikely to get the amount of airflow the system was designed to deliver —  and reduces the System’s ability to cool & heat your home.  Worse yet — this puts a strain on; the furnace blower, the A/C outdoor unit + the furnace heat-exchanger.  You’ll have higher energy bills and shortened HVAC System’s lifespan (because it must run longer and harder).

During summerA potential problem caused by reduced air flow is that it can cause the A/C cooling-coil to freeze up.  As the freezing begins, air flow keeps lowering — until the cooling coil is a block of ice.  If allowed to run in this state for very long — this can damage the outdoor unit.  If this happens — it’s typically less expensive to replace the outdoor unit than repair it (mostly determined by the outdoor unit’s age).

Click Here To See A Frozen Central A/C Cooling Coil (inside the furnace): Frozen Central A/C Cooling Coil

During winterLow air flow causes the furnace’s heat-exchanger to overheat.  The heat-exchanger allows heat from the burners to flow inside it — and household air to flow along its outside.  Each time the furnace runs — the metal in the heat-exchanger expands.  After the heating cycle ends, the heat-exchanger cools and the metal contracts.  Over time, most heat-exchangers crack as a result of expanding & contracting.  When this happens, it’s typically less expensive to replace the furnace than to replace the heat-exchanger (mostly determined by the furnace’s age).  When the heat-exchanger is subjected to recurring overheating — it fails sooner because it’s not designed to expand and contract so much.

Click Here To See A Cracked Furnace Heat-Exchanger: Cracked Furnace Heat Exchanger



The furnace filter’s thickness is key in maximizing air filtering capacity and minimizing air flow reduction through the furnace.

  • A 20″x 20″ 1″ thick pleated filter has 4.7 square feet of filtering surface area.  **
  • A 20″ x 20″ 4″ thick filter has 15.4 square feet of filtering surface area.  **

NOTE: Your furnace will accept only a 1″ thick OR 4″ thick air filter.  You can’t install a 4″ thick air filter unless the furnace is set up for one.

  • A 1″ thick spun-fiberglass filter and a 4″ thick MERV-7 filter — create the same decrease in furnace air flow. **
  • A 1″ spun-fiberglass filter catches <20% of particles sized 3 — 10 microns.  ***
  • A 4″ Merv-7 filter catches 50% — 69% of particles sized 3 — 10 microns.   This includes most of the; pollen, dust & dust mites, mold spores, and cooking smoke.  ***
  • A human hair ranges from 20 to 75 microns thick.

Click Here For A Chart Showing Particle-Size Removal Ability Of A Furnace Filter — By MERV Rating: Particle Size Removal By MERV Rating

Copy This Link Into Your Browser For A Video Explaining MERV Ratings For Air Filters:

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2. A Furnace-Mounted Air Cleaner Cleans Indoor Air Without Reducing Air Flow

There are many brands & models available.  We discuss one brand & model below.  AccuClean is made by American Standard HVAC (same company as Trane).


The American Standard HVAC AccuClean™ System Delivers Clean Indoor Air As Well As The Highest MERV-Rated Disposable Air Filter

Copy The Link Below Into Your Browser To See A Brochure For American Stanard’s “AccuClean™  Whole-Home Air Filtration System:

NOTE: Al’s Plumbing, Heating & A/C Sells & Installs American Stanard HVAC Products.

  • AccuClean removes up to 99.98% of allergens & particulates down to .3 (about 1/3) micron in size — (a human hair is 20-75 microns wide).   This includes; pollen, dust & dust mites, mold spores, pet dander, skin flakes, smog, tobacco smoke, and cooking smoke.
  • AccuClean delivers indoor air as clean as the highest-rated (MERV-20) air filter does — while only marginally reducing furnace air flow.
  • According to their listing — Lennox’s X6672, MERV-16, 5-inch thick, disposable air filter is Consumer reports #1 rated. 
  • Amazon sells a 5-Pack of this filter for $335.00.
  • At this price for disposable air filters — it would soon be less expensive to install a Furnace-Mount Air Cleaner that’s cleanable, reusable, and lasts for many years.
  • AccuClean is 100 times more effective than a standard 1-inch disposable furnace filter.
  • AccuClean earned The Asthma & Allergy Friendly® Certification.   The Asthma & Allergy Friendly Certification Program is an independent program administered in the United States by Asthma & Allergy Foundation.  The smallest particles in the air are what gets trapped in your lungs — and can trigger asthma and allergy attacks.

AccuClean Features:

  • A cleanable Pre-Filter traps large airborne particles.  This allows the cleanable collection cells to operate for longer periods of time between cleanings.  The Pre-Filter is cleaned by vacuuming every 1-2 months.
  • AccuClean’s™ Collection-Core has over 10,000 air-cleaning cells to capture particulates & allergens.
  • AccuClean’s™ Collection-Core is cleanable — two cleanings per year is recommended.
  • AccuClean filters the air throughout your entire home around 7 times per day.
  • AccuClean’s whole-home filtration has the lowest airflow restriction (through the furnace) —  and the highest efficiency of all filtration systems available when this article was written.
  • Different models match your furnace’s size and air-flow requirements.

3. Separate, Room Size Air-Purifying Machines To Clean Indoor Air **

NOTE: In the details for each machine — you’ll find the maximum square footage it serves.   

Most portable air cleaner serve 1 room.

To filter the entire house — you’ll need multiple machines. 

If you have a large home, it’s likely less expensive to purchase a furnace-mounted air cleaner.  


Copy This Link Into Your Browser To See A HEPA Air Filter:

  • HEPA stands for High-Efficiency Particulate Air Filter.  HEPA rated filters must remove at least 99.97% particulates within the air.  HEPA filters deliver very clean indoor air.
  • Based on Research at the University Of Minnesota — HEPA rated filters capture nearly every particulate of any size. ***  They can capture viruses, bacteria, pollen, allergens, and more.
  • Nanoparticles (smaller than 0.3 microns) have so little mass — that they get bounced around in random, zigzag patterns.  Though Nanoparticles are too small to be caught by a HEPA filter,                                                    their zigzag movement patterns cause most of them to become trapped.
  • Particles 0.3 microns or larger are too big to move in zigag patterns.
  • HEPA filters remove particles 0.3 microns or larger
  • Some filters are a “HEPA Like” filter.  These are not as effective as genuine HEPA filters.  We discuss only true HEPA filters within this article.

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How Effective Is A (true) HEPA Filter Against Coronavirus?

** Researchers At The University Of Minnesota Tested True Hepa Filters: ***

  • Coronavirus particles’ size = 0.06 — 0.14 microns.
  • Their study showed that HEPA filters capture 99.99% of particles smaller 0.10 microns.  *** 

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There Are 2 Types Of Pollutants In The Air

Airborne Particles 

  • Particles / Particulates — Can Be Removed With A HEPA or “HEPA Like” air filter — (less effective than a true HEPA — but still very effective).  These particles trigger allergies.
  • HEPA filters capture airborne particles — including dust,  pollen, and mold spores down to about 0.3 microns (a human hair is 60 — 120 microns in size.).
  • HEPA filters do nothing to remove airborne gasses.

Airborne Gasses

  • Gaseous pollutants: include (but not limited to) burning of fossil fuels, paints, varnishes, cleaning products, pressed-wood furniture, and new carpets.  That “new smell” is VOS’s off-gassing from the product.
  • Volatile organic compounds (VOCs): indoor VOCs are largely emitted by paint, furniture, household chemicals, and other similar sources.
  • Some VOC’s are carcinogenic (may cause cancer).
  • Dedicated UV-Lights do nothing to remove airborne particulates.  They remove airborne gasses.  UV Lights can’t help with allergies — as allergies are triggered by airborne particulates.

photo a/c coil with uv light

Shown: Dedicated (no filter) UV Light Located Inside The A/C Cooling Coil Inside A Furnace


Volatile Organic Compounds (VOCs) Within The Air

According to the U.S. EPA: *5

  • Volatile Organic Compounds area (VOCs) gasses are emitted from certain solids or liquids.  See the second *5 Source below for a list of VOS’s.
  • UV light alone can’t destroy VOC’s.
  • UV shining on a surface coated with Titanium Dioxide (TiO2) — creates a process called Photocatalytic Oxidation.   A Photocatalytic Air Cleaner oxidizes (destroys) Volatile Organic Compounds (VOCs).
  • Photocatalytic Oxidation will reduce or eliminate VOC’s from indoor air. *5
  • See the warnings below about these devices. **

*5 Source:

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The Two Most Common Ways To Remove Airborne Gasses

  • An Activated Carbon Filter.
  • A UV light shining onto a surface coated with Titanium Dioxide (TiO2).  

NOTE: UV light alone has a limited ability to remove airborne gasses.


A HEPA Air Filter Air Cleaner With An Activated Charcoal Filter

Removes Both Airborne Particles & Gasses


SHOWN: Hathaspace Smart, True HEPA Air Purifier — 5-in-1 Large Room Air Cleaner & Deodorizer 

Click On Image To; View Product, Read Details, or Order From

This is a very highly rated air filter (by Amazon customers).   At the time this was written, there were nearly 2,250 reviews — with overall rating of 4.6 (out of 5)

NOTE:  This filter Uses Activated Charcoal — Instead Of  UV Light & Titanium Oxide


The Amazon Web Page Says:

  • Purify Air from home-air pollutants like; dust mites, pollen, mold spores, pet dander, pet hair, odors, smoke — and volatile organic compounds (VOCs).

5-in-1 Air Filter:

  • Pre-Filter — captures large particles
  • Anti-Bacterial Filter — targets bacteria & germs.  The manufacturer makes no mention if this filter can be cleaned — and no mention if a replacement anti-bacterial filter is available.
  • True HEPA H-11 Filter that filters 99.97% of particles as small as 0.3 microns.
  • Cellular Activated Carbon Filter — absorbs odors and gases. 
  • Ion Generator (can be separately controlled) produces negatively-charged ions to target the most stubborn odors
  • Air Quality Sensor: Measures air-quality — and adjusts the fan speed as needed. 
  • Air Quality Display: — displays the air-quality level (green, yellow, red). 
  • Uses Hathaspace HSP-001 Certified Replacement Filters (1 Set: Carbon + HEPA) — also available from Amazon


  • A Medical Grade HEPA Filter Is Also Available (on same Amazon page as HSP-0001).
  • True H-13 Medical-Grade HEPA is superior to standard HEPA filters.
  • H-13 Medical-Grade HEPA filters capture airborne particles down to 0.1 microns.


SHOWN:  1 Room (True Hepa Air Filter) Air Purifier 

Removes Both Airborne Particles & Gasses

Click On Image To: View Product, Read Details, or Order From

The Amazon Web Page Shows:

  • 3 IN 1 AIR PURIFIER FOR HOME True HEPA air filter reduces up to 99.97% of harmful germs, dust, pollen, pet dander, mold spores, and other allergens as small as .3 microns from the air
  • UV Light works with Titanium Dioxide — to help kill airborne viruses and Volatile Organic Compounds.  UV light can be turned on and off separately.   
  • TRAPS ALLERGENS Pre-filter traps dust, pet hair, and other large particles while extending the life of the HEPA filter
  • REDUCES ODORS Activated charcoal filter helps to reduce unwanted odors from pets, smoke, cooking fumes, and more
  • SETTINGS Choose between three3 speed settings and an (optional on/off) UV light
  • ROOM SIZE: 22-inch purifier filters air 4x per hour (at max speed) in rooms up to 167 sq. feet.


SHOWN:  1 Large Room (True Hepa Air Filter) Air Purifier 

Removes Both Airborne Particles & Gasses

Click On Image To: View Product, Read Details, or Order From

The Amazon Web Page Shows:

  • 4 IN1 AIR PURIFIER : True HEPA air filter reduces up to 99.97% of harmful dust, pollen, pet dander, mold spores, and other allergens as small as .3 microns from the air ; Input Voltage: AC120 Volt ; 60 Hertz
  • UV Light works with Titanium Dioxide — to help kill airborne viruses and volatile organic compounds.
  • TRAPS ALLERGENS : Pre filter traps dust, pet hair, and other large particles while extending the life of the HEPA filter
  • REDUCES ODORS : Activated charcoal filter helps reduce unwanted odors from pets, smoke, cooking fumes, and more
  • RECOMMENDED FILTERS : Replace with Guardian filter C (FLT5000) or a 4 pack of Guardian carbon filters (FLT28CB4)


** There Is Current Concern About Titanium Dioxide (TiO2) — And Increased Cancer Risk

There are many companies manufacturing Photocatalytic Oxidation Technology (PCO) products –that utilize a combination of ultraviolet (UV) light and metal surface coated with a minimum of Ti02 — to achieve a catalytic-reaction that breaks down airborne gases and kill pathogens in the air stream.

When these devices are located within an airstream treating air being supplied to an occupied space — the potential for inhalation of the TiO2 particles is possible for the following reasons:

  • UV light may eventually break down the binders in the glue holding the TiO2 coating onto the surface. *6
  • Some Photocatalytic Oxidation products manufacturers offer air filters coated with TiO2.   When the filter is changed — fibers may dislodge into the airstream and travel into occupied space.


Studies On Titanium Oxide Exposure:

  • In 1988, The National Institute for Occupational Safety and Health (NIOSH) recommended that TiO2 be classified as a potential carcinogen and that exposures be controlled to as low as feasible.  This recommendation was based on the observation of the formation of cancerous lung tumors in a chronic inhalation study with rats at 250 mg of fine TiO2 per 35 cubic feet of air.
  • Later, a 2-year inhalation study showed a statistically significant increase in lung cancer in rats exposed to ultrafine TiO2 at an average concentration of 10 mg of fine TiO2 per 35 cubic feet of air.
  • Two recent epidemiologic studies have not found a relationship between exposure to total or respirable TiO2 and lung cancer.
  • An elevation in lung cancer mortality was observed among male TiO2 workers in the latter study.  However, when the study’s data was compared to the general population — there was no exposure-relationship found.
  • Disease mortality was not increased significantly in any of the epidemiologic studies.
  • The Occupational Safety and Health Administration (OSHA) states the permissible exposure limit for TiO2 is 15 mg per 35 cubic feet of air.

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According to a 2011 publication by the Centers For Disease Control (CDC): “Much further testing will be required on nano Ti02 particles.  Nanoparticles are of greater concern because, the smaller the particle, the deeper it can lodge into the lungs, where it will permanently reside — causing inflammation leading to possible tumors or cancer.

The National Center for Biotechnology Information (NCBI) states:  “Until relevant toxicological and human-exposure data (that would enable reliable risk assessment) are obtained — TiO2 nanoparticles should be used with great care.” *7

*6 Source:


NOTE: Al’s Plumbing, Heating & A/C Makes No Observations Nor Recommendations Regarding Any Air Cleaning Device Using Titanium Dioxide (TiO2)