What’s in the Air We Breathe?

Guest Column 
Last Word from The Hestia Report
By John P. Lapotaire, owner, MicroShield Environmental Services 

Indoor air quality (IAQ) is a hot topic in today’s sluggish real estate market.  We find ourselves opening the door to a whole new set of challenges each time we view a home that may have been sitting for awhile.  Questions race through our minds as we turn the key: “Will this home have that healthy home smell? Will it have a musty stale smell? Did they have pets or smoke?” And finally: “What will I have to do if there is an air quality problem?”

Research has shown that the indoor air quality in our homes can be worse than that of outdoor air.  We also know that if a home has been unoccupied, possibly with the A/C off, the air quality will be much, much worse. According to the American Lung Association, indoor air pollution poses a threat to respiratory health and everyone should consider doing what they can to improve the quality of indoor air. 

So what can we do to improve the indoor air quality?  Is there a way we could clean the house that would actually improve the air quality?  There is, and it’s not much different than the way you may be cleaning already.  But first, you will need to understand a little about indoor air quality and what causes poor indoor air quality in our homes.

So just what is Indoor Air Quality?

  • IAQ:  Indoor Air Quality refers to the effect of the air inside a home on its occupants. 
  • GOOD IAQ: The quality of air in a home, which has no unwanted gases or particles in it at concentrations that will adversely affect the occupants.
  • POOR IAQ occurs when gasses or particulates are present at an excessive concentration so as to affect the satisfaction or health of the homes occupants.
  • Acceptable indoor air is defined by ASHRAE: “Air in which there are no known contaminants at harmful concentrations and which a substantial majority (usually 80%) of the people exposed do not express dissatisfaction.” – ASHRAE 62-1999
    • ASHRA – American Society of Hearing Refrigeration and Air Conditioning Contractors
    • ASHRAE 62-1999 Ventilation for Acceptable Indoor Air Quality
    • ASHRAE 55-200, Thermal Environmental Conditions for Human Occupancy

An indoor environmental consultant or industrial hygienist can asses your indoor environment and help you identify the source and type of indoor pollutant in your air. Here are the three basic areas of indoor air pollutants according to the Centers for Disease Control and Prevention (CDC), which places air pollutants into three general categories:

  1. Particulates
  2. Bioaerosols
  3. Volatile Organic Compounds (VOC’s)


Common indoor air particulates include dirt, dust, fibers, tobacco smoke particles and fireplace or wood stove soot. Airborne particles can range from 0.1 microns in size to 100 microns in size.


Bioaerosols are microorganisms or particles, gases, vapors, or fragments of biological origin (e.g.., alive or released from a living organism) that are in the air. Bioaerosols are everywhere in the environment.

Volatile Organic Compounds (VOC)

Carbon-based chemicals that easily evaporate at room temperature. Some VOC’s have odors; other VOC’s have none. Odor does not indicate the level of risk. There are thousands of different VOC’s produced and used in our daily lives.

Let’s drill down a bit. If you take a typical home that is occupied and the A/C is set to a reasonable 74 degrees Faranheit, you should have little or no IAQ issues in the home.  If you take the same home and increase the humidity above 60%rh you can have mold growth on furniture and areas of little or no air circulation.  The mold growth can then sporolate, which will introduce particulates into the air.  The mold can also release mycotoxins into the air which are bioaerosols.  If you replace the moldy couch with a new one, you get that new couch smell as the couch off gasses introducing VOC’s to the indoor environment.

One house, one issue, all three CDC indoor pollutants introduced into the home.  You may be thinking that’s not likely to happen, but what I just described is a real case scenario that took place in a home in Central Florida.  The fix for this home was to reduce the humidity within the home and collect and remove the excess particulates.

Whether you hire an indoor environmental consultant or you simply want to begin the process of improving your indoor air quality (IAQ), there are a few things you will need to address that will have an immediate impact on the home’s indoor air quality.

  1. Particulates
  2. Humidity
  3. Filtration
  4. Housekeeping

Let’s start with particulates.  When an indoor environmental consultant assesses a home they will always evaluate the level of particulates within the home.  This is the primary health indicator of the air within the home.  From there, consultant can determine if sampling is necessary to identify the particulates.  In most cases it’s much more important to determine the cause and origin of the particulates than to establish the specific type, genus, or species of the particulates.  Either way the particulates need to be reduced or removed. 

If the source of the particulates is mold due to flooding or water intrusion a written protocol or procedure may be necessary.  The removal of the mold should be preformed by a remediation professional who will follow the protocol to the letter and is familiar with all of the processes and procedures.  This would always be followed by post remediation clearance test by the consultant or hygienists.  In order to successfully complete a remediation project, it is important to have clear goals in place from the very beginning.  The IICRC S520 states that, “the primary goal of mold remediation is to safely restore Condition 2 or Condition 3 structures, contents or systems to Condition 1.”

      • The S520 is the Mold Remediation Standard and Reference Guide.  The  IICRC Institute of Inspection, Cleaning and Restoration Certification Institute of Inspection, Cleaning and Restoration Certification

Particulates can accumulate within the home from either inside sources or outside sources.  Some of the common indoor particulate sources include:

  • Cleaning
  • Cat and dog dander
  • Candles
  • Incense
  • Refrigerators
  • Perfume
  • House Plants
  • Humidifiers
  • Computers
  • Printers
  • Those cute little desk top water fountains
  • Fungal spores
  • Pollen
  • Tobacco smoke
  • Combustible appliances
  • Asbestos fibers

These sources can be controlled and or eliminated from a home by controlling the source of irritants. The particulates that we can control are referred to as:

  1. Inhalable Particles – particles that deposit in the nose, mouth, pharynx, and larynx and have a diameter in the 100 microns (µm) range.
  2. Thoracic Particles – particles that deposit in the trachea, bronchus and have a diameter in the 10 micron (µm) range.
  3. Respirable Particles – particles that deposit in the lower portion of the lungs or bronchioles and have a diameter of less than 2.5 microns (µm).

These are the particle sizes that we will be addressing as we improve the air we breathe.

Next you will need to keep a healthy level of humidity.  Dust mites and mold love moisture, so keeping humidity around 30-50% helps keep them and other allergens under control.  In Florida, the addition of a humidistat and dehumidifier can greatly improve the indoor air quality of a home.  The humidistat turns on the homes air conditioning when the humidity reaches the set relative humidity (preferably not higher than 55%rh) just as the thermostat activates the homes air conditioning when the temperature reaches a set temperature (preferably not higher than 76°F). 

Maintaining the proper humidity level helps reduce moisture in the indoor air and can effectively control allergens. High humidity levels in Florida can produce musty odor and/or a clammy feeling to the air in the summer and condensation on windows in the winter.

Often the principal source of higher humidity in a home is a family’s living habits. One person’s breathing produces 1/4 cup of water per hour, cooking for a family of four produces approximately five pints of water in 24 hours, showering puts 1/2 pint of water into the air, and bathing puts 1/8 pint of water into the air.  Adding only four to six pints of water to the air raises the relative humidity in a 1,000 square foot home from 15-60%, assuming the temperature is constant.

Next on our list is filtration.   Each time the air conditioning system cycles air into the home, armies of particulates are propelled through the supply ducts and discharged throughout your home into the air your family breathes.  More specifically the air you breathe is filled with the particulates allowed to pass through your air conditioning filter.  The filtration you choose has a tremendous affect on your indoor air quality so you should use the highest level of filtration that your system allows.

There are many filters available on the market today.  The most common are the one inch filters found in supermarkets, hardware stores and home supply retailers. All these filters guarantee a percentage of effectiveness, but that can be misleading.   

Standard throwaway filters are only designed to protect the air handler and have little or no capability of collecting fine particles.  Washable filters are very restrictive to airflow and are difficult to clean thoroughly and are rarely maintained at the proper level.  Electronic air cleaners are 95% efficient at .3 microns when new and clean. They reduce in efficiency very quickly as they load with particles and are difficult to clean thoroughly.  Many homeowners just don’t take the time to properly clean these filters on a regular basis, so they rarely work at the efficiency in which they were designed. 

Large four- to five-inch media filters, on the other hand, have a large amount of filter surface and allow for good air flow.  They can collect a large amount of dust and particles above one micron in size and most don’t have to be replaced for six to 12 months.  These filters are typically MERV rated at 8 to 11.  MERV (Minimum Efficiency Reporting Value) is an industry standard rating system that can be used to compare filters made by different companies.  The MERV rating of a filter describes the size of the holes in the filter that allow air to pass through.  In a nut shell, the higher the MERV rating, the smaller the holes in the filter, and the more particles it can filter. Residential filters commonly have MERV ratings of 1-11.

  • A MERV rating of 6 means the filter is 35-50% minimum efficient at capturing particles, sized 3.0-10.0 microns.
  • A MERV rating of 7 means the filter is 50-70% minimum efficient at capturing particles, sized 3.0-10.0 microns.
  • A MERV rating of 8 means the filter is 70% minimum efficient at capturing particles, sized 3.0-10.0 microns.
  • A MERV rating of 11 means the filter is 85% minimum efficient at capturing particles, sized 3.0-10.0 microns.


Now for the housekeeping side of air quality improvement.   You first have to reduce the humidity in the home by using your range, bathroom and cooking exhaust fans.  You should also ensure that they are vented to the outside.  You should check your dryer exhaust vent regularly to ensure it isn’t clogged.  Reduce the number of plants in the home and/or water them less so they release less water vapor.  And you can add a humidistat and mechanical dehumidifier to your air conditioning system. 

Now you need to get rid of those pesky particulates. The key to that is to collect and remove particles by using a HEPA vacuum.  Don’t forget to vacuum all porous surfaces including upholstered furniture. For best results, vacuum two or more times each week and change your HEPA filter regularly.  On tile floors you can collect and remove particles by mopping which will collect the dust that your HEPA vacuuming leaves behind. You can skip the soaps and cleaners and just use plain water to capture any lingering dust or allergens. There are also new microfiber mops that reportedly capture more dust and dirt than traditional mops and don’t require any cleaning solutions whatsoever. 

For the particle dust build up within the home, you will need to collect and remove it as well.  For most people this means dusting using a simple feather duster, or a cloth of some kind, and some kind of dusting spray. This just relocates the dust particulates and introduces bioaerosols & VOC’s into the air.  Remember the key is to collect and remove not relocate.   I recommend using the new microfiber dust cloth that can capture more dust and dirt than traditional fibers and don’t require any cleaning solutions.

To help prevent the particulates from entering the home, place large floor mats at every door. People track in all sorts of particles via the dirt on their shoes. A door mat reduces the amount of dirt, pesticides, and other pollutants from getting into your home. If the mat is big enough, even those who don’t wipe their shoes will leave most pollutants on the mat — not the floors in the home.

Don’t forget to change your air conditioning filters every 30 days or as prescribed by the manufacturer.  Not maintaining your air conditioning filter is a major source of indoor air problems.  Some of the higher MERV rated media filters can be changed as infrequently as every six months.   While you are changing that filter, check the A/C drain line and every three months flush it with an algae control cleaner to prevent clogging.

Remember to keep your home dry: Control humidity levels between 35% and 50% to prevent dust mites and an indoor environment that can lead to mold growth.  Fix any leaks you have in your home as soon as you find them.  If you have a flood, take immediate action and dry the area out, including all affected furnishings, within 48 hours to prevent mold growth. 

So, now when asked what you can do about the “air you breathe” you will have plenty to say because you know what is in the air.  And remember good IAQ for people already suffering from allergies can reduce the symptoms of those allergies, often reduce medications for allergies, and lead to more relaxing sleep.  Furthermore, good IAQ can have a substantial impact on our children by preventing allergies, delaying the occurrence of an allergy, or the reduction of allergy symptoms.




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