Indoor air quality is important to government agencies, schools, businesses, building staff, and occupants because it can impact both positively and negatively the health, comfort, well being, and productivity of building occupants.

Studies have shown that the growth of microorganisms such as bacteria and fungi in and around a building serves as a source of indoor bio-pollutant. World Health Organization (WHO Guidelines for Indoor Air Quality, 2009) concluded

Microbial infested HVAC system
Microbial infested HVAC system

that the most important effect is increased prevalence of respiratory symptoms, allergies and asthma, as well as perturbation of the immunological systems. According to the report building dampness (supporting factor for microbial growth in buildings) varies widely from country to country and climatic zone. Dampness is estimated to affect 10-50% of all indoor environments in North America, Australia, Europe, India, and Japan.

According to U.S. Environmental Protection Agency (EPA) most Americans spend up to 90% of their time indoors and many spend most of their working hours in an office environment. Environmental studies conducted by the independent scientific groups, EPA and others have shown that indoor air pollutants levels are greater than levels found outside.

What are some types of indoor air pollutants that may affect my building?

  • Biological contaminants: the biological contaminants can consist of bacteria, viruses, fungi (mold), dust mite allergen, animal dander, insect biodetritus, fibers and fiberglass, pollen, cockroach allergen, etc… and may result from inadequate maintenance and housekeeping, water spills, inadequate humidity control, condensation, or may be brought into the building by occupants, infiltration, or ventilation air. Allergic responses to indoor biological pollutant exposures cause symptoms in allergic individuals and also play a key role in triggering asthma episodes for an estimated 15 million Americans.
  • Chemical pollutants:  Volatile organic compounds (VOCs) are organic chemicals.  VOCs are numerous, varied, and ubiquitous. They include both human-made and naturally occurring chemical compounds. Chemical pollutants can include tobacco smoke, emissions from products used in the building (e.g., office equipment; furniture, wall and floor coverings e.g. formaldehyde; and cleaning and consumer products) accidental spill of chemicals, and gases such as carbon monoxide and nitrogen dioxide, which are products of combustion.
  • Particles. Particles are solid or liquid substances which are light enough to be suspended in the air, the largest (8 microns and greater) of which may be visible in sunbeams streaming into a room are typically non respirable. However, the smaller particles (7 microns and smaller) that you cannot see are likely to be more harmful to health since these are considered respirable. Particles of dust, dirt, or other substances may be drawn into the building from outside and can also be produced by activities that occur in buildings e.g. operation and maintenance practices, housekeeping practices, printing, copying, operating equipment, construction, remodeling, people….

Is establishing baseline IAQ conditions in my building important?

Yes, as Yogi Berra once said “if you don’t know where you are going, you might not get there?”  Indoor air quality is no different.  If you don’t know the present IAQ conditions of your building are and you are having IAQ upgrades performed to enhance your buildings IAQ then how would you know that you improved those conditions if you didn’t have a baseline to start with?  You wouldn’t.

It is not practical to design a universal guideline fit for all in terms of exposure and health because immunity varies greatly from individual to individual. EDLab at Pure Air Control Services performed a 10 year study analyzing more than 7,000 buildings and over 25,000 environmental samples that were collected across the United States and abroad.  The building types included both commercial and residential.  The majority of samples analyzed were tested positive for bacteria and fungi.

In this study the average (normal baseline) concentration of air-borne culture-able (viable) bacteria was 175 CFU (Colony Forming Unit)/m3, and the fungal concentration in ambient air was recorded at 350 CFU/m3. The average concentration of non viable air-borne mold/fungal elements was estimated at approximately 1,000 cts (counts)/ m3. These baseline numbers are used as a reliable indicator for an expected average of disseminated microbial (bacteria/fungi only) concentrations in today’s modern buildings.

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