Indoor Pollutants


There are numerous sources in a home that can generate unhealthy pollutants. They include combustion byproducts from oil, gas, kerosene, and wood heaters, water heaters, fireplaces, cook tops, gas grilles, building materials, asbestos, fiberglass insulation, cabinets,  paints, stains, adhesives, carpets, hardwood and vinyl floors, furniture, upholstery fabrics,  central heating and cooling systems and humidification equipment. Add cars, lawnmowers, pesticides, yard chemicals, household cleaning and maintenance products, personal care products, hobby products, air freshners and even candles.   Air pollutants are categorized into three groups, chemicals, particulates and biological growth. The more common pollutants found in homes include, 

Carbon Monoxide

Carbon monoxide (CO for short) is colorless, tasteless, and odorless, but highly toxic. It many countries, its the most common cause of fatalities from air poisoning. CO combines with hemoglobin in our blood to produce carboxyhemoglobin. This usurps the space in hemoglobin that normally carries oxygen to our body's cells.  Heavier levels of inhalation can cause nausea, dizziness, headaches, and a lack of coordination. When carboxyhemoglobin levels reach 50%, seizures and coma are common. Eventually the cummlative effect causes death.

Carbon Monoxide is typically a byproduct from buring oil, gas or wood. So the sources include furnaces, water heaters,  fireplaces, wood stoves, pool heaters, gas cook tops and grilles. Automobiles, generators, and lawn care equipment are also common sources. 


Keeping the CO sources listed above serviced and in proper working order will reduce the risk of CO poisoning. When replacing  any gas furnace or water heater, ALWAYS specify "sealed combustion". Sealed combustion appliances are much safer than conventional designs as their combustion process is largely isolated from the living space. 


Any home with combustion applicanes, fireplaces or attached garage should include a  you CO monitor. A CO monitor is preferred over an alarm because it is more sensitive to low levels of CO exposure. Low levels of CO over time is now suspected in a whole host of health complications. 

Symptoms of CO Poisoning

Biological Growth










Tobacco smoke

Lead & Arsenic





Mold Spores

Pollen & Ragweed

Pet Dander

Dust Mites & their Feces

Insect parts

Gases & Chemicals

Combustion Byproducts



Volatile Organic Compounds (VOC's)

Carbon Dioxide


Yard Chemicals

Household Cleaners

Personal Care Products

Dry Cleaning Solutions

Air Freshners

"If you were able to chose the kind of brain injury you were to incur, it would be better in terms of the potential for recovery to have a stroke, concussion in a motor vehicle accident, etc. than carbon monoxide poisoning."

                                                                                                                                                                                  David G Penny, PHD


Formaldehyde, or CH2O, is an organic compound that exists as a gas at room temperature. Formaldehyde is invisible, but has a distinctive pungent smell. Sources of formaldehyde in a home include wood burning stoves and fireplaces, fiberglass insulation, laminate and hardwood flooring, new carpet, wood paneling, plywood, oriented strand board (OSB), medium-density fiberboard (MDF), particle board, engineered wooden beams, cabinets and furniture.  Additional sources of formaldehyde include hair care products, especially hair straighteners, a new mattress and dry cleaning chemicals. 


In high concentrations, formaldehyde can cause irritation of the eyes, nose, and throat, coughing, rashes, and fatigue. It may also be a cause of cancer and other serious health problems.


Testing a home for formaldehyde is easy and relatively inexpensive. 


Volatile Organic Compounds (VOC's)

Volatile Organic Compounds" (VOCs), is a catch-all term for carbon based chemicals that are emitted from a variety of sources. The term "volatile" simply describes their propensity to vaporize into the air making them easy to breathe. Chemists identify this attribute by saying the chemical has a "low vapor pressure", which simply means they have a low boiling point. A number of VOC's will vaporize in room temperature air. Technically formaldehyde falls in this group as well. But it is so prevalent, it warrants its own section. 









Among the common sources for indoor VOCs identified by the EPA are a number of building products, laminates, paint, stain, cleaning solutions, pesticides, refrigerant, gasoline, solvents, glue and adhesives. As you can see, your home probably has many VOC sources, so being aware of them is important.


There are several pages of various compounds classified as VOC's by EPA. The list is replete with hard to pronounce chemicals like Trichloroethene, Carbon tetrachloride and Methyl-tert-butyl ether (MTBE), found in plastic plumbing pipe. 

Water Damaged Home

Uncontrolled moisture and water damage can turn a home into a toxic mix of mold microbes, and harmful chemicals, before you can say antimicrobial. The agents of disaster are biological organisms, which are or were alive.

If you are building a new home, VCS testing should be an essential prerequisite. Every family member should be tested. The outcome will tell you the level of vigilance in controlling moisture to protect your family.



Mold testing is easy and relatively inexpensive. If you suspect you have a problem, you've recently had water damage or you're buying a new home, it is exceptionally prudent to have the space tested for mVOC's.

This complex mixture of contaminants present in the air from these sources can create a toxic stew that can wreak havoc on your body. Some call it mold illness. But the clinical term is Chronic Inflammatory Response Syndrome (CIRS). Some of its symptoms include:


•Fatigue  •Weakness  •Aches  •Muscle Cramps  •Headache  •Sensitivity to Ligh  •Red Eyes  •Blurred Vision  •Sinus Problems •Cough  •Shortness of Breath  •Abdominal Pain  •Diarrhea  •Joint Pain  •Memory Issues  •Decreased Learning  •Confusion •Disorientation  •Skin Sensitivity  •Mood Swings  •Appetite Swings  •Excessive Thirst  •Increased Urination  •Numbness •Vertigo  •Metallic Taste  •Tremors


There are so many possible sources of toxic biological compounds that can lead to these symptoms; it is rare that a single compound can be identified as the sole cause. Since no one thing can be deemed as solely responsible for the sickness, the sole cause becomes the water-damaged home itself. In extreme cases, the home becomes unlivable.


Uncontrolled moisture is usually a result of construction defects, such as

  • water management details that were poorly designed, installed or ignored all together,

  • roof leaks,

  • missing or faulty flashing,

  • damp or wet basements and/or crawl spaces,

  • plumbing or drain leaks,

  • defective exhaust fans,

  • oversized, improperly installed and poorly maintained heating, ventilating and cooling systems.






The bottom line is, moisture drives the growth of fungus, mold, bacteria and virsues. AND it is just as apt to occur in a new home as in an existing older home.

We live in the Era of Dangerous Buildings with 50% of our buildings (NIOSH, 2011) having water damage so the likelihood that you won’t ever be exposed to dangerous buildings is quite low.                                                                  

Dr Richie Shoemaker, MD

VOC Monitors

The health effects of organic gases are varied, ranging from irritation of the eyes, nose, and throat to dizziness and nausea to even more serious problems, including cancer and damage to the central nervous system. Recently, specific VOC's have been implicated as asthma triggers. Every VOC has a different level of toxicity and the effect on health is influenced by its concentration and the length of exposure. 


The majority of new homes tend to have higher levels of VOC's. Although older homes are not exempt, since homeowners can easily introduce a variety of sources through cleaning chemicals, pesticides and personal care products. Some VOC's found in building products tend to linger for months to years. 


Testing a home for "total VOC's (TVOC) is easy to do, costing $250 to $300. There are also electronic sniffers that sample the air for certain VOC's and give some type of readout indicating their concentration. 

Below is a list of some of the dangerous compounds and a brief explanation of each. 


  • Fungi - A single-celled or multicellular organism. Fungi can cause infections in both healthy persons and those with compromised immune systems.  


  • Bacteria - Single-celled microorganisms which can exist either as independent (free-living) organisms or as parasites (dependent upon another organism for life).


  • Mold  - Mold refers to multiple types of fungi that grow in filaments and reproduce by forming spores. Mold may grow indoors or outdoors and thrives in damp, warm, and humid environments. Mold can be found in essentially any environment or season. 


The most common types of mold found indoors include Cladosporium, Penicillium, Penicillium, Alternaria,and Aspergillus. Stachybotrys chartarum (also known as Stachybotrys atra and sometimes referred to as "black mold") is a greenish-black mold that can also be found indoors. Stachybotrys grows on household surfaces that have high cellulose content, such as wood, fiberboard, gypsum board, paper, dust, and lint.


  • Spore - Molds reproduce by forming tiny spores that not visible to the naked eye. Mold spores are very hardy and can survive under conditions in which mold cannot grow, such as in dry and harsh environments. These spores travel through outdoor and indoor air. When mold spores land on a surface where moisture is present, mold can start to grow.


  • Mycotoxins - toxic chemicals that are present on spores and small fragments of mold and fungus that are released into the air.


  • Endotoxins  - also called Lipopolysaccharides (LPS), are cell wall components of Gram negative bacteria. They are shed into the environment of high moisture upon death of the bacteria. LPS cause inflammatory responses via signaling pathways in the body, releasing inflammatory cytokines. LPS aggravate existing lung disease (asthma, HP), can cause inflammation of the lungs and are synergistic with mycotoxins.


  • Microbial Volatile Organic Compounds (mVOCs) - Microbes can release organic compounds into the air when there is adequate food supply for such “secondary metabolite” production. These volatile compounds, called mVOCs for short, can give basements their distinctive musty odor.  well.


The good news is only about 25% of the population has the genetic make up from their immune response gene called HLA-DR that will make them exceptionally susceptible to CIRS. If you suspect you may be in this group, a visual contrast sensitivity test (VCS) could provide some indication. THIS TEST SHOULD NOT BE CONSIDERED A MEDICAL DIAGNOSIS. It may simply give you evidence that you may have been affected by bio toxins. A positive outcome should be followed by proper diagnosis by a physician specializing in environmental medicine. The test is free and self administered at





Dust Mites

House dust mites are microscope bugs that primarily live on dead skin cells regularly shed from humans and their animal pets. A typical mattress can contain tens of thousands of dust mites. Nearly 100,000 mites can live in one square yard of carpet. Just thinking of these dust mites living in your pillow by the millions, eating your dead skin and hair is enough to make you sick (literally and figuratively).  


Dust mites are nearly everywhere; roughly four out of five homes in the United States have detectable levels of dust mite allergen in at least one bed." Don't you feel better now, know they don't bite or sting; and your allergic reaction is only due to burying your face in a pillow full of their feces? 

House dust mites are microscope bugs that primarily live on dead skin cells regularly shed from humans and their animal pets. A typical mattress can contain tens of thousands of dust mites. Nearly 100,000 mites can live in one square yard of carpet. Just thinking of these dust mites living in your pillow by the millions, eating your dead skin and hair is enough to make you sick (literally and figuratively).  


The Mayo Clinic, WebMD and NIH collectively provide this list of typical symptoms of an allergy to dust mites;  You may experience all or just some of them:


Hay fever  • Watering eyes  •Runny nose  •Sneezing  •Asthma, difficulty in breathing  •Infantile eczema  •Itchy, red or watery eyes •Nasal congestion  •Itchy nose, roof of mouth or throat  •Postnasal drip  •Cough  •Facial pressure and pain  •Frequent awakening •Swollen, blue-colored skin under your eyes  •Frequent upward rubbing of the nose, in a child



The presence of house dustmites can be confirmed microscopically which requires collecting samples from mattresses, couches or carpets. Also, it requires the use of a microscope with sufficient magnification and the technical ability to recognize house dust mites under the microscope. In general practice, testing is unnecessary.  Dustmites are extremely common in household environments. They virtually always show up in a test, so testing just adds expense.  A better question than "are dust mites present?" is "How can I control or remove them?"

Dustmite hygiene requires (1) thoroughly vacuuming mattress pillows and the base of the bed. (2) use a mattress cover (3) wash sheets and pillow cases in at least 130°F water. But the most essential requirement is maintaining  relative humidity at 50% or lower.  


Maintaining proper humidity is extremely difficult with oversized and poorly designed cooling systems.  But what makes matters worse is oversizing cooling equipment is a widespread epidemic. In those cases, a supplement dehumidifer is the only hope of stemming the proliferation of dustmites. 


Particulates or particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets. These tiny particles vary greatly in shape, size and chemical composition, and can be made up of many different materials such as metals, soot, soil and dust. The size of particles is directly linked to their potential for causing health disorders. 

Some particles, such as dust, dirt, soot, or smoke, are large enough to be seen with the naked eye. Others are so small they can only be seen with an electron microscope.


Particle size is expressed in microns or µm. One micron = 1/25,400th of an inch. In other words, its really small. The illustration  shows a comparsion. Notice a human hair is 50 to 70 microns in diameter.


Sometimes particles are expressed as PM, meaning particulate matter, followed by the size. For example. PM2.5 indicates Particulate Matter at 2.5µm and PM10 reflects Particulate Mater at 10 µm.


The respiratory system has defense mechanisms to help prevent airborne particles from getting into the lungs and causing harm. When we inhale, the air is drawn in through the nose or mouth into the upper respiratory system, which consists of the nasal passages, trachea, and conducting airways (bronchi and bronchioles). The air becomes moist and makes numerous twists and turns through the nasal passages and branching airways. 


Particles larger than 10 µm cannot usually get past our nasal hair and make the turns necessary to make it into our lungs. But, smaller particles <10 µm are capable of traveling into the pulmonary part of the lungs (the respiratory bronchioles, alveolar ducts, and alveolar sacs). This particles are called respirable.

The smaller the particle, the deeper it travels into the lungs. Thus, .3 µm particles will travel deeper into the lungs than PM2.5. Moreover, smaller particles are made up things that are more toxic, like heavy metals and cancer causing organic compounds. So, PM2.5 can have more serious health effects than the bigger PM10.


Soluble particulates simply discolve. But others are removed by particle-eating cells called macrophages. Macrophages transport the insoluble particles either to the lymph system or back up the airway where you swallow them or sneeze them out. 


There are now serious questions about how ultrafine particles smaller than 0.1 µm) are able to be absorbed into the body and distributed in the cells. They do not appear to be encapsulated by macrophages and seem to be entering cells and transported throughout the body by other, yet unknown, mechanisms. This has significant implications for the potential health effects caused by particles in this size range.


Scientific studies have linked particle pollution, especially fine particles, with a series of significant health problems, including:


 hypertension  nonfatal heart attacks  irregular heartbeat  aggravated asthma  decreased lung function  •increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing  •Premature death in people with heart or lung disease.


Particle pollution can cause coughing, wheezing, and decreased lung function even in otherwise healthy children and adults. 

Studies estimate that thousands of elderly people die prematurely each year from exposure to fine particles.


Radon is a colorless, odorless, radioactive gas that occurs naturally in all parts of the U.S. It is a probable carcinogen It is the leading cause of lung cancer in nonsmokers. Radon is estimated to be responsible for the death of about 21,000 people in the United States every year.


Radon concentrations are reported in picocuries per liter (pCi/l), which is a measure of radioactivity in a volume of air. The only way to determine the concentration of radon in a home is to perform a test. Every home should be tested. Even if the house next door tested negative, it has no relevance to how your home will test. Fortunately, testing is relatively inexpensive and easy to do. Check with your county environmental health department or call a professiona. 

The EPA currently has an action level of 4 pCi/l and homes that test at or above that level should be mitigated to reduce the radon concentration as low as practical. New homes should always include "radon resistant construction" features. 

Nitrogen Dioxide

Nitrogen dioxide (NO2) is a nasty-smelling gas. Some nitrogen dioxide is formed naturally in the atmosphere by lightning and some is produced by plants, soil and water. The major source of nitrogen dioxide in homes is the burning of fossil fuels: coal, oil, gas, kerosene heaters Un-vented gas stoves and heaters are the worst offenders.


NO2 acts mainly as an irritant affecting the mucosa of the eyes, nose, throat, and respiratory tract. Extremely high-dose exposure may result in pulmonary edema and diffuse lung injury. 

Continued exposure to high NO2 levels can contribute to the development of acute or chronic bronchitis. Low level NO2 exposure may cause increased bronchial reactivity in some asthmatics, decreased lung function in patients with chronic obstructive pulmonary disease and increased risk of respiratory infections, especially in young children.


Average levels of NO2 in homes without combustion appliances is about half that of outdoors. In homes with gas stoves, kerosene heaters, or un-vented gas space heaters, indoor levels often exceed outdoor levels. Venting the NO2 sources to the outdoors, and assuring that combustion appliances are correctly installed, used, and maintained are the most effective measures to reduce exposures.


No one likes living with roaches, ants, bugs, mice, rats and bats. Chemical pesticides seem to be the most popular option in repelling or destroying these annoying pests. Rat and rodent poisons, roach traps, roach and ant spray, kitchen, laundry, and bath disinfectants that kill mold and mildew, and flea and tick products used on pets are commonplace in nearly 90% of American homes. 


The toxicity of pesticides is indicated by the signal words, Caution, Warning and Danger. The EPA also has strict guidelines pesticides be tested for their potential to cause cancer. 


People are exposed to pesticides by enhaling their chemicals, accidentially eating them or getting them on their skin. Pesticides are tranported in air and vary between 

rooms. They can settle on surfaces such as furniture. Once settled out, they may stay or be resuspended in air depending on drafts and currents.  

In homes, inhaling pesticides is the major source of exposure.  Exposure to pesticides may cause the following:

  • Irritation to the eyes, nose, and throat.

  • Damage to the central nervous system and kidneys.

  • Increased risk of cancer.


Remember that the "-cide" in pesticides means "to kill". When not used properly, pesticides may be dangerous to humans.  


Chronic exposure to some pesticides can result in damage to the liver, kidneys, endocrine, and nervous systems. Symptoms of exposure to pesticides may include:

  • Headache.

  • Dizziness.

  • Muscular weakness.

  • Nausea.

Both the active and inert ingredients within pesticides can be organic compounds, which could add to the levels of organics inside home. Some health effects associated with organics include:


  • Eye, nose, and throat irritation.

  • Loss of coordination.

  • Nausea.

  • Damage to the liver, kidneys, and central nervous system.

  • Symptoms of exposure to organics include:

    • Irritation of the eye.

    • Nose and throat discomfort.

    • Allergic skin reaction.

    • Nausea.

    • Difficulty in breathing.

  • Declines in serum cholinesterase levels.

  • Vomiting.

  • Nosebleed.

  • Fatigue.

  • Dizziness. 

Designing a home that is less attractive to pests is the most effective way to minimize your exposure to pesticides. After all, no pests eliminates the need for pesticides. Controlling humidity discourages a number of pests while sealing cracks and holes will minimize their entryways. Eliminating their food sources is another strategy to discourage activity.


To reduce exposure, remove shoes before tracking pesticides from outside through the house. A good practice is to have a pair or two of indoor shoes at the door.


If you must use pest control measures, investigate safer, more benign options. For example, borate is very effective against self grooming insects. And its less toxic than ordinary table salt. 


Asbestos was once commonly used in home construction for its ability to insulate and resist fire. Asbestos fibers are so small that they can easily be inhaled by someone without them knowing it. Many forms of asbestos are now banned by the federal government. Therefore, asbestos is a major risk in older homes rather than newer ones.

Asbestos produces no immediate symptoms, so there are no early-warning signs. In the long term, it can contribute to abdominal cancer, lung cancer, and mesothelioma. There is even a condition known as asbestosis, which occurs when the fibers cause scarring in the lungs.


If your home has asbestos, it does not necessarily mean that you are in danger. If the asbestos is of good quality and left undisturbed, it will not release fibers into the air to be inhaled. If some operation needs to be performed on your home that might lead to the asbestos being disturbed, it is best to use professionals. If you are worried about asbestos levels in you home, the wise action may be to seal the asbestos off rather than try to remove it, which may just lead to more asbestos being released into the air.