13 Common Indoor Air Quality Conditions That Plagues Us All

"Number 13 Made In Daisy Flower" by dan


Mold and water damaged building materials

When leakage occurs it results in the growth of mold that in turn results in the release of pungent smelling and irritating volatile organic compounds, and allergenic mold spores into your air. Persons with allergies or asthma often have reactions to such contaminates in the air while others may have no reaction at all. People with compromised immune systems may even contract infections from some molds. Some of the most common mold related infections are chronic allergenic fungal sinusitis, this is a type of allergic like reaction and infection that results from spores germinating in the sinuses, the agent of infection is usually Alternaria mold spores. Other persons may develop lung infections caused by certain species of Aspergillus growing in the lungs. Fungal infections are more a product of a person's poor health than of the environment they are in. Home inspectors, mold inspectors and other building investigators may use a moisture meter to detect moisture hidden inside water damaged building materials.

Infrared cameras can also be used to detect moisture hidden inside walls and other areas by measuring very slight temperature differentials between cooler wet surfaces and warmer dry surfaces. Where there is moisture mold is often not far away. Drying up water within 24 to 48 hours and repairing leaks can go a long way in preventing mold problems.

Elevated RH

Relative humidity is simply a measurement of the amount of moisture in air compared to the maximum amount of moisture that same air could hold at a given temperature and pressure. Example: if your humidity is at 50%RH then your air is about 1/2 full in regards to the amount of moisture it can hold, this is a normal indoor level.

If your humidity is at 65%RH it is about 65% full in regards to the amount of moisture it can hold, levels this high can support mold growth & dust mite growth.

If you have mold growing on furniture, walls, and clothes, in areas where leaks never occurred it is not the result of mold just deciding to spread to new areas, such inexplicable cases of mold spreading is the result of elevated humidity. Moldy clothes in closets is a perfect example of mold caused by humidity. In addition you might experience condensation problems on cold surfaces such as AC registers. At 100% humidity the air cannot hold the moisture anymore and that humidity or air born moisture starts to condensate or change from humidity to water droplets. Condensation on cold vapor barriers, cold AC components, and cold pipes can cause serious mold problems. To control such mold you must understand the reasons for such humidity problems this is easier said than done. Humidity below 30% can cause drying of the lips and the mucous membranes in the throat, nose, or sinuses, this in turn causes irritation and some believe it may even lead to a higher likelihood of contracting colds because of damage to the membranes. It an also cause static electricity build up in offices that can in turn put computers at risk of lose of data. Keep your humidity between 30% and 60%RH.

Dust mites and particulates

Air contaminated with excess particles can also cause negative reactions. Some particles cause direct irritation when levels are elevated. In the case of house dust people do not typically have a direct allergenic or irritation related reaction. Common dust is as much as 80% dead human skin cells thus the dust itself is not seen as a forging invader by your body. When people have allergic reactions to common household dust it is not the dust causing the problem but allergenic proteins found in dust mite feces. Particles counters can be used to measure airborne particulates, particle counters are highly sensitive scientific instruments that use an internal laser to count particles passing through it that are of a predetermined size range. Good quality pleated filters at your AC unit return can help reduce dust, also use a good quality vacuum that is equipped with a hepa filter. A bad vacuum cleaner will remove dust from your carpets then blow it into your face.

Carbon dioxide

High carbon dioxide levels are not typically a direct threat to human health in home and commercial properties. High carbon dioxide levels usually indicate a lack of adequate outdoor air being introduced into the building. Dust, chemicals, body odors and other indoor air pollutants often build up along with carbon dioxide in poorly ventilated buildings, and it is these other indoor pollutants that result in indoor air quality complaints and health complaints. According to Parat and others "A properly maintained and operated mechanical ventilation system can reduce indoor Bioaerosols concentrations by limiting infiltration of outdoor Bioaerosols and by diluting those from outdoor sources ( Parat et al., 1994, 1996 ).

According to American Society of Heating Refrigerating and Air Conditioning Engineers ASHRAE 62-89 Outdoor air supply into the building should be at least 20 cubic foot per min per person in offices and thus help maintain carbon dioxide levels below 1000 ppm. Newer requirements recommend levels no more than 700 ppm higher than outdoor carbon dioxide levels. Outdoor air that is being introduced into a building must meet the US EPA National Primary Ambient Air Quality Standards is short it must be clean or it must be properly filtered.

In conclusion letting clean dry outdoor air into homes and commercial buildings can help dilute and flush out indoor pollutants.

Carbon monoxide

WARNING: Carbon monoxide can rapidly rob your blood's ability to properly absorb oxygen thus it can be deadly. If carbon monoxide levels at your property are dangerously high then emergency measures such as immediate evacuation may be deemed necessary. Even if slightly elevated further investigation by a qualified, licensed, specialist is recommended and appropriate repairs or other measures may be needed. The leading cause of deaths from carbon monoxide poisoning in homes is automobile exhaust escaping from garages, however improper combustion of fuel in gas appliances, improper ventilation of combustion gases to the exterior, and cracked heat exchangers are also important sources of carbon monoxide exposure.

"At low concentrations the health effects are fatigue in healthy people and chest pain in persons with heart disease. At higher concentrations it causes impaired vision and coordination problems, headaches, dizziness, confusion, nausea. It can cause flu like symptoms that clear up after leaving home. Carbon monoxide is fatal at very high concentrations.

Average levels in homes without gas stoves 0.5 to 5 ppm.

Levels near properly adjusted gas stoves are 5 to 15 ppm.

Near poorly adjusted stoves 30 ppm or higher." The above information is from epa.gov/iaq/co.html

If you have an attached garage, or any types of gas burning appliances or devices in your building or home have it checked for carbon monoxide. Make sure that gas appliances are working properly and properly vented to the exterior.


Volatile organic compound also known as VOC's are common indoor pollutants composed of organic chemicals that evaporate into the air easily, they often cause chemical odors, respiratory irritation, headache, and other indoor air quality related complaints. At certain high levels they can be dangerous. These chemicals are released by paints, paint thinners, varnish, new carpets, new cabinets and furniture that contain particle board, household cleaners and air fresheners, fuel gas, improperly vented combustion devices, photocopier machines, blueprint machines, and many other sources. Refrain from the excessive use of household product that contains chemicals.

Purchase paints and new carpets with low emission levels of voc's. Solid wood cabinets and furnishings contain less voc's than those composed of particle board type materials. When using chemicals or when installing new carpets, paints, cabinets, and other furnishings let the property air out in a safe and reasonable way. Healthy buildings will typically contain less than 1 ppm or even less than .5 ppm.


Formaldehyde is a common volatile organic compound that results in lots of indoor air quality problems, it is found in glues used in the manufacture of particle board, wood veneers, wood furniture, plywood, and other wood products.

It is also found in some spray-on insulating foams. These resins slowly give off formaldehyde over time. Formaldehyde is one of the more common indoor air pollutants. At concentrations above 0.1 ppm in air, formaldehyde can irritate the eyes and mucous membranes, resulting in watery eyes. If inhaled, formaldehyde at this concentration may cause headaches, a burning sensation in the throat, and difficulty breathing, as well as triggering asthma symptoms.

The above recommendations made in regards to other volatile organic compounds also applies to formaldehyde.

Sewer gas

Hydrogen sulfide it the gas that produces rotten egg or sulfur like odors in well water, sewer systems, rotten eggs, and other areas where water and organic compounds have a lack of oxygen. Hydrogen sulfide odors may lead to complaints of foul odors and also eye & throat irritation cough and shortness of breath. According to wikipedia ".0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic rotten egg odor of hydrogen sulfide."10 to 15 ppm is the borderline concentration for eye irritation.

Drain pipes have letter u shaped curve that traps water, you have seen this under your sinks, and this trapped water is intended to keep sewer gas from backing up from the sewer system and into your home. Make sure that drains such as basement floor drains, sink drains, and even toilet bowls etc contain some water. If the water evaporates from a drains p trap then sewer gas will back up into the building. In vacant properties anaerobic bacterial may invade your water heater and produce sulfur gas odors in your drinking water, in properties with well water similar bacteria may invade your well water system and create strong sulfur odors. The latter two conditions are annoying but are typically thought of as harmless and can be repaired by a plumber or well water service company.


Nitrogen dioxide is composed of nitrogen and oxygen atoms, incomplete combustion in vehicles or gas burning appliances can create this pollutant and improper venting of such combustion gases from gas appliances, loading docks, and parking garages, can result in the gas entering into the indoor environment. Nitrogen dioxide is a respiratory irritation. If you have any types of gas burning appliances or devices in your building or home have the property checked for nitrogen dioxide, carbon monoxide and other combustion gases. Make sure that gas appliances are working properly and properly vented to the exterior.


Ozone is a fresh smelling oxygen molecule composed of 3 oxygen atoms, the oxygen we breathe is made of just two oxygen molecules. In the upper atmosphere ozone blocks out harmful UV light thus protecting living organisms below, at ground level ozone is an air pollutant that can have harmful effects on our respiratory system in fact ozone is a constitute of smog pollution. Asthmatics are especially at risk from the effects of ozone exposure.

Despite claims of safe levels of fresh smelling ozone emitted by ozone producing machines, some ozone machines have been found to produce ozone at levels that may result in respiratory irritation in some persons. It is true that ozone can break down smoke, odors, and other air contaminates but the break down product follow the most basic laws of physics and thus do not disappear from existence but instead these products have end up in the air where some of them can serves as irritants to sensitive persons.

  • According to the EPA some health effects of overexposure to ozone are:
  • Decreases in lung function
  • Aggravation of asthma
  • Throat irritation and cough
  • Chest pain and shortness of breath
  • Inflammation of lung tissue
  • Higher susceptibility to respiratory infection

For more info please visit: epa.gov/iaq/pubs/ozonegen.html

Negative pressure

Sometimes negative pressure in homes and other buildings causes humid outdoor air to be pulled inside in hot humid environments, and radon to be pulled into buildings in environments where radon is problematic. Negative pressure can pull dangerous levels of carbon monoxide out of gas burning devices. Smelly crawl space or attic air can also be pulled into such buildings. One of the possible causes of negative pressure is leaky AC ducts in crawl spaces and attics because the ducts leaks the buildings air outdoors resulting in less air pressure indoors than outdoors, another cause of negative pressure can be the use of ventilation fans and hoods vented to the exterior. If not corrected negative pressure can cause serious problems in areas with radon or humidity thus positive pressure is desirable in hot humid environments and in areas with radon problems. In temperate climates when it is cool or cold and dry outside then negative indoor pressure may not be a problem. Positive indoor pressure is to be avoided because it can push the buildings humid indoor air into walls where it cools and forms condensation. Inspectors often use digital manometers or smoke from smoke pens to detect negative pressure.

Physical and psychological stressors

Stressors play an important role in building occupants resistance to and perception of indoor air quality problems. According to the Canada's Technical Guide to the Investigation of Indoor Air Quality in Office Buildings stressors are "environmental parameters, such as lighting, noise, vibration, and ergonomics. Stressors can cause occupant complaints that are similar to complaints caused by indoor pollutants. Thermal comfort also plays an important role in building occupants resistance to and perception of indoor air quality problems.

According to the above referenced source thermal comfort is "A state of mind in which a person feels satisfaction with the thermal environment. The factors affecting thermal comfort are air temperature, stratification, mean radiant temperature, air motion, relative humidity, activity level, and clothing." Ventilation rate is also an important factor to consider. Ventilation rate is the amount of outside air that is supplied to the interior space.


Last but not least on are list of 13 sinister Indoor Air Quality (IAQ) problems is radon, a colorless odorless gas that finds its way into buildings through cracks in the foundations. If a building is negatively pressurized then that negative pressure can cause radon to be actively sucked into the building. Radon is very common in some areas, to find out if radon is a problem in your property it is recommended that you have it tested. Radon is a carcinogen or cancer causing agent. Often persons living with radon will have no clue that the problem exists till it is to late. Even in non smokers radon causes lung cancer. If you know of a household where a non smoker developed lung cancer you should suggest that the home or the victims previous residence be tested for radon gas. According to the EPA and the surgeon general radon is responsible for 20,000 deaths a year.

Image courtesy of dan / FreeDigitalPhotos.net