An invisible army has invaded your office and work space. An army of tiny particles floating by the millions in every cubic foot of air inside the space. No matter where you turn, you draw them in with every breath.

They have you surrounded.

Sitting in your well decorated, carpeted, air conditioned work space, you wonder about this invisible army. Where is the evidence?

The size of the problem has nothing to do with the size of the pollutants. In fact, over 99% of the particles contaminating indoor air can't be seen without microscope. While you can't see the majority of air contaminants, you can see their effects.

Some health effects are useful indicators of Indoor Air Quality problems. Allergies could be related to the Pollen, mould spores, dust mites, bacteria. Viruses and fungi may be affecting most people with infections. Lingering smoke may be causing respiratory distress or coughs in some people.

There is no single manner in which these health problems appear. In some cases, problems begin as people enter their offices and diminish as they leave. Sometime there are outbreaks of illness among many workers in a single building; in other cases health symptoms show up in individuals only. Unusually high rates of health and comfort complaints from occupants may be related to Indoor Air Quality. Another simple method of detecting poor air quality is to use your nose. If you sense a high "stuffiness level" and there is a musty odour,
the ventilation in the house might be inadequate.

Measuring in Microns Every cubic foot of air you breathe carries a mixture of millions of tiny annoyances. In small concentrations these particles and gases may make life miserable for you. In significant concentrations, they can make you sick. How tiny can you think? A micron is one millionth of a meter or .00004 of, an inch. Approximately 397 microns would fit over the dot above the letter 'i'. The eye of an average needle measures about 749 microns across. And a one inch square postage stamp measures 25,400 micros on one side.

Things that can indicate that your work environment could have an indoor air quality problem include smelling or stuffy air, dirty central cooling or heating equipment, moisture seepage on walls and ceilings, signs of water leakage and areas where books, documents drapes and other items become moldy.

Another way to judge whether your indoor environment has or could develop air quality problems is to identify potential sources of indoor air pollution. Many air pollutants are not detectable by sight or smell for example Radon gas. Carbon Monoxide and Nitric Oxide. Other pollutants are evident only in high concentrations. Formaldehyde for example, may have pungent smell at high levels but no smell at lower - yet irritating levels.

Detecting the Indoor Air Pollutants

Devices for detecting many pollutants in air and water are available but detection is an expensive exercise. However, chemicals like cleaning agents, aerosols, pesticides have a detectable odour. Pungent odour from certain types of new carpeting or paints can be a sign of presence of formaldehyde in the space. Odor of mold and mildew denotes the presence of organisms and microbes. Musty smell is due to the presence of high humidity and moisture having condensed on surfaces. This condensed moisture provides a breeding ground for mold and fungus and catalysts for other pollutants. Cigrettee smoke is detectable through the strong odour it leaves behind on all furnishings and furniture.

Identification of source of pollutants will provide an indication that vour work space needs more fresh air to be brought in to dilute the concentration of pollutants that tend to build up in conditioned, enclosed spaces.

Can Indoor Air Quality be Measured?

You have read so far that indoor air can be more polluted than outdoor air because of the build up and higher concentration of the contaminants when the same is recirculated in, conditioned space. Even though individually most of the contaminants are not harmful but a higher concenration can cause adverse effect on health. Can indoor air quality be measured in terms of the level of contaminants present?

Although it is extremely expensive and difficult to detect or measure the indoor air contaminants, CO2 (carbon dioxide) has been recognised by ASHRAE (American Soceity for Heating, Refrigeration and Airconditioning Engineers) as the surrogate ventilation index of the only measurable variable.

Carbondioxide levels in air airconditioned room is a good indicator of occupancy and ventilation rate within a space. Let us see why carbon dioxide is taken as a measure of Indoor Air Quality!

CO2, by itself is not considered air indoor air contaminant. Humans are the major source of CO2. As people exhale C02, they also exhale and give off a wide range of 'bioeffluents'. These bioeffluents include gases odours, particulate, bacteria, viruses. When these bioeffluents are allowed to build up in space, due to poor ventilation, occupants complain of fatigue, headache and geneneral discomfort. The assumption is that if there is sufficient ventilation to remove the human generated contaminants, there will be no discomfort.

Outside levels of CO2, are relative constant and range between (350 to 600 ppm), inside levels will never be below the outside level. The amount of CO2, in the space can give us an indication of the number of persons within the space. Therefore, the concentration of CO2, in a space can provide an indication of the actual ventilation rate per person within the space. If the CO2, levels are higher than 1000 ppm (parts per million then it is an indication that not enough outdoor air is coming in to dilute the CO2 level. Therefore the indoor air is being recirculated and the levels of the other pollutants the enclosed space must be high.

CO2, does not create these symptoms but elevated CO2, concentrations will often occur at the same time other pollutant levels build up.

The real value of CO2, in Indoor Air Quality control is an indicator of ventilation rates within a space.