"During this century, dramatic episodes of excess mortality caused by ambient air pollution convincingly established that atmospheric contamination by human activities can adversely affect health.

So starts the two part State of the Art article in The American Review of Respiratory Disease on indoor air contamination, its health risks, sources and elimination. It is not an overly lengthy report but it contains a summary of the findings of over 400 scientific papers on the topic, that have been written in the last few years.

The air contaminants that it focuses on are: respirable particles, nitrogen dioxide, carbon monoxide, biological agents, formaldehyde and organic chemicals. By addressing these areas one at a time they were able to address sources and effects and evaluate potential methods of avoidance and removal.

In an effort to inform our readers about indoor air pollution, we have added some of what we know to the findings and will give a brief summary of each of these areas.

Particulate or respirable particles are put into the air through occupant activity, tobacco smoke, wood and coal stoves, fireplaces, unvented kerosene healters and some that enters from outdoors and attached facilities. The EPA and OSHA have set standards for particulate levels per cubic meter of air.

They are 265 micrograms for a 24 hour period, 75 micrograms for an annual average amount. By contrast a typical home they will have from 10 to 100 micrograms of particulate per cubic meter of air, a crowded restaurant or airplane smoking section can have up to 700 mictrograms per cubic meter and a home with a fireplace can have up to 1000 micrograms of particulate per cubic meter of air.

Respirable particles can lodge deep in the passages of the respiratory tract and accumulate causing congestion and breathing impairment.

Nitrogen dioxide is a by-product of combustion. It is in automobile exhaust, gas stoves, cigarette smoke and kerosene heater emissions. Nitrogen dioxide is not toxic at levels that we are generally exposed to, but being an oxidant it is an irritant. Studies show a slight correlation between the decreased lung function and gas stove use in the home. Where nitrogen dioxide levels are high like near heavy traffic or near a poorly vented stove, one can feel a tightness in the chest, irritated eyes and burning of the sinus.

Carbon monoxide is a highly poisonous gas that has the same sources as nitrogen dioxide. It is colourless odourless and tasteless. It has 200 times the affinity for red blood cells that carry oxygen than oxygen. Therefore acute explsures to carbon monoxide have symptoms that reflect oxygen deprivation to the vital organs, particularly the brain and heart. The symptoms start with tachycardia and confusion and reach up to heart attack or coma.

The EPA limit for maximum 8 hour exposure is 8 parrts per million. Levels in homes with gas stoves can range from 2 to 15 ppm and buildings with attached garages and homes that use the gas stove for heat can have carbon monoxide levels in excess of 50 parts per million.

Biological agents such as viruses, bacteria, actinomycetes, fungal spores, algae, amoeba, insect parts and droppings, and animal and human dander contaminate indoor air environments and are critically dependant on moisture for their survival. Humidifiers, air conditioning systems, laundry hampers, bathrooms, air conditioning couls, garbage cans, and places with water damage are suitable environments for them to proliferate.

Places that are dark and damp are ideal for their development. If an excess of biological agent develops it can result in the transmission of disease, the development of mold, mildew and foul odours.

Formaldehyde from glues, fiberboard, pressed board and plywood, particle board, carpet backing, fabric and foam insulation is a colourless gas with a characteristic odour. The recent recognition of these numerous sources of formaldehyde in indoor environments has prompted concern over this pollutants health hazards.

Because of its volatile nature it is irritating to the eyes and respiratory tract. It is also a suspected carcinogen. Many studies have been performed and, beyond the fact that it is highly irritating, formaldehyde has not been conclusively proven to pose a significant health hazard at the levels in home and office to which we are normally exposed. Chronic occupational and acute accidental exposures have proven to be hazardous.

VOC or Volatile Organic Compounds are organic chemicals that evaporate at room temperature. For that reason they are prevalent in most things that need to dry. Paints, adhesives, cleaners, cosmetics, furnishings, printed material, dry-cleaned clothes, pesticides, fungicides, herbicides, gasoline and cigarette smoke.

Organic chemicals are thought to be the largest contributing factor in sick building syndrome. The distinguishing characteristic of these air contaminants is their sheer numbers. At any given location there can be over 100 airborne organic chemicals present.

In one study researchers found a total of over 350 airborne organic chemicals at five different locations in one facility, a nursing home. Their neurotoxic and carcinogenic effects are discussed in a related article in this issue.

One of the principal factors that has contributed to the dramatic rise in indoor air contamination is the energy efficient construction and conservation measures that have been taken since our first oil crisis in the early seventies.

These measures have reduced the average number of air changes per hour in most indoor spaces dramatically. This gives contaminants a longer time to accumulate and bring about harmful concentrations of contaminants that prior to airtight practices remained in lower safer concentrations.

One of the frequently proscribed methods of controlling harmful concentrations is proper ventilation, particularly at the source. An example of this is range hoods and bathroom fans. Many central heating and air conditioning units have been equipped with filters to trap particulate and some of the biologica agents.

Newer filters have been developed that trap or eliminate contaminants through adsorption, absorption or electrostatic precipitation. In order for these devices to be effective the air needs to be circulated across the filtering medium. Air that does not come into contact with the element does not get treated.

Ambient air purification devices are those that emit a sanitizing substance into the space to deal with contamination problems in the space at large. Ambient devices include air ionizers, ozone generators and extract of grapefruit seed.

Air ionizers emit negative ions that attach to smoke and dust particles giving them a charge so they attach to each other and get weighed down and out of the air or attach themselves to the walls and furniture. Dirt collection on the walls has been a major criticism of negative ion generators.

To solve this problem better models have collector plates that are easily cleaned to pick up the charged particles and substantially reduce this problem Extract of grapefruit seed is very effective at eliminating pathogenic contaminants such as bacteria and virus.

Ozone is effective against the four major groups of air contaminants and acts on each in different ways. It acts on biological agents through a process called cell lysing.

It punctures the protective coatings of biological contaminants such as bacteria, germs, virus, fungal spores, amoebas and other pathogens, and eliminates them from indoor environments. It is interesting to note that this is the same method that mother nature uses to keep these elements in check in the environment. Ozone is present in fresh outdoor air at typical levels of .02 to .05 parts per million.

Ozone reacts with airborne gasses such as formaldehyde, carbon monoxide and ammonia and reduces them to free oxygen, nitrogen, carbon dioxide, and water vapour. It coagulates airborne contaminants like smoke particles, dust and pollen into clusters that are large enough to get caught in filters or precipitated out of the air. It oxidizes organic chemicals from cleaning products and pesticides, etc... and breaks them down into harmless salts, carbon dioxide and water.

Ozone is a powerful oxidant and can be irritating to the respiratory tissue. Chronic exposure to amounts of .3 parts per million (10 times natures .03-.05) can cause pulmonary edema, cillial paralysis and fibrosis. Pulmonary edema is the swelling of bronchial passages.

This constriction of breathing passages is dangerous, particularly in persons with respiratory problems such as asthma and emphysema. Cillial paralysis is the immobilization of the microscopic hairs that work continuously to pass inhaled particles up out of the depths of the lungs.

When rats were exposed to high concentrations of ozone they demonstrated a reduced resistance to germ carried diseases. Scientists attributed this reduced resistance to the inactivation of the cilia. Fibrosis is the formation of collagen type scar tissue in areas that are chronically irritated by ozone.

Healthy adult males experienced irritated sinuses and a tightness of the chest while exercising at .1 part per million which is two to three times the natural level.

Isn't ozone smog? No. Ozone is formed when sunlight comes in contact with the photochemical hydrocarbons (pollution) in automobile exhaust. On still sunny days where there are a lot of cars the ozone produced by this process can reach levels that are well above the EPA mandated level for maximum exposure which is .12 ppm.

Although theses ozone episodes, as they're called, can be irritating to the respiratory tract of those that come in contact with them, they are natures way of doing its part to clean up the mess we are making of our environment. In smog ozone can be thought of as the fireman at the fire.

The bigger the fire, the more firemen. These firemen over a period of hours do a good job of breaking down many of the toxic pollutants in automobile exhaust. The next time you hear about ozone in smog, think about what a shame it is that we don't have cleaner transportation technologies.

The odour threshold for ozone is .1 part per million which is just about the level at which it begins to be an irritant to occupants who are exerting themselves and breathing heavily. Where ozone generating air purifiers are concerned there are two types; fumigants and ambients.

A fumigating air purifier is one that produces in excess of the EPA limit of .12ppm and should never be operated while the space is occupied. Ambient purifiers are those that never produce ozone in excess of levels found in nature, .05ppm. A small amount of ozone will do the same job as a large amount, it will just take a longer period of time.

Ozone has all the properties that the American public is looking for in indoor air decontamination. It works on the biological agents, the particulate, the dangerous gases and on the organic chemicals.

Being as powerful an oxidant as it is, it needs to be administered judiciously so as to avoid the problems associated with higher concentrations. Indoor levels of ozone are typically zero. If you feel that you're breathing stale sewage – you probably are. An excellent solution to this is to put the nature back into your indoor air environment with the use of a safe ozone generator.

VOC's are Volatile Organic Compounds. According to the EPA, “VOC's are emitted as gases from certain solids or liquids. VOC's include a variety of chemicals, some of which may have short and long term adverse health effects. Concentrations of many VOC's are consistently higher indoors (up to ten times higher) than outdoors. VOC's are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and home furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers and photographic solutions.”

“Organic chemicals are widely used as ingredients in household products. Paints, varnishes and wax all contain organic solvents, as do many cleaning, disinfecting, cosmetic degreasing and hobby products. Fuels are made up of organic chemicals. All of these products can release organic compounds while you are using them, and, to some degree, when they are stored.”

“EPA's Total Expossure Assessment Methodology (TEAM) studies found levels of about a dozen common organic pollutants to be 2 to 5 times higher inside h omes than outside, regardless of whether the homes were locted in rural or highly industrial areas. Additional studies indicate that while people are using products containing organic chemicals, they can expose themselves and others to very high pollutant levels, and elevated concentrations can persist in the air long after the activity is complete.”

The following is a short list of dangerous toxic hazardous vapour sources generated by construction materials degassing, which become part of Indoor Air Pollution.

Don't take our word for it...

CAUTION: Read all warning labels to become familiar with the chemical contents/ingredients of the products you use that can cause serious problems. They all have one thing in common; avoid breathing the vapours. The manufacturers have done their job. They issues the warning(s).

Check the pressed wood products (plywood, partical board, paneling fiberboard, laminated plastics, shelves, and doors) read the label. They contain phenol resins or urea resins and toxic glues.