Indoor Air Quality

April 24, 2000
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Solving common indoor air-quality problems need not be difficult if you know what to look for.

Below is a list of some common problems I've met with in my capacity as a consultant. Other IAQ investigators might have other opinions based on the frequency of problems they encounter. Nonetheless, this list is representative of the issues almost any person involved in IAQ difficulties will come across.

Problems & Solutions

1.Dried Out Sewer Traps 'S' or 'P' traps prevent sewer odors from entering occupied spaces. However, once the water seal in such traps has dried due to evaporation, sewer odors may freely exit the system. As a result, any malodorous substance poured down a drain anywhere in the system can escape into occupied spaces. Such problems are especially likely to occur in buildings where the intended use has changed, yet hidden floor drains remain (e.g., shower floor drains remain after the conversion of a residential facility into an industrial research occupancy).

SOLUTION: Adding a quart or two of water to the drain usually fills the trap and blocks off offending odors.

2.Blocked Filters If an air supply system is designed or balanced with a particular type of air filter in place and higher efficiency (i.e., higher resistance to flow) material is used, it may result in decreased overall air flow. In other cases, filters are forgotten and become severely blocked with debris. In a worst-case scenario, such filters can serve as reservoirs for microbial growth leading to biological contamination of the HVAC (Heating, Ventilation, Air Conditioning) systems.

SOLUTION: Periodically, replace HVAC filters with the same filter type as originally used in the new HVAC system. 3.User Processes Anyone who has ever entered a shopping mall only to be greeted by the unpleasant odors from a hairdressing salon will recognize the broad category of complaints caused by user processes. Examples in the industrial environment are limitless, but they have one common feature: unique odors accepted by many can still be objectionable to others.

SOLUTION: While controlling such IAQ problems over the long term can be costly, efforts aimed at isolating the offending operation from the rest of the facility are simple and can be immediately effective. Keep doors to the problem area closed and ensure that product containers of noxious substances are capped while not in use.

4.Outside Air Damper Problems In many facilities, outside air dampers are the first air handler element incoming air encounters. If the outside air is extremely wet, as in humid periods or during heavy rains, the air dampers or their actuators can get wet and eventually rust into a fixed position. If this position is closed or only partly open, it may ultimately lead to IAQ issues.

SOLUTION: To quickly remedy problems caused by rusted dampers, set these louvers manually to more open positions until a professional maintenance company can be hired to do the necessary repairs.

5.Loading Dock Re-entrainment At facilities where clean fresh air intakes are located adjacent to loading docks, IAQ problems are sure to occur. Perhaps the most common example of this problem is re-entrainment of diesel engine exhaust resulting from idling truck engines at loading docks in cold climates.

SOLUTION: Company policy can require drivers to shut off their engines while loading or standing.

6.Construction Activities Combining disparate building uses is almost certain to result in IAQ problems. Construction or renovation work in an occupied facility is one such example. Modern construction poses all types of indoor air pollution possibilities, from extremely fine dusts resulting from drywall installation to vapors emanating from curing paints, adhesives, carpets and coatings. While physical barrier separation of the construction zones is often accomplished, isolation of an HVAC system serving both areas can be overlooked. In such instances, odors and contaminants from the construction area travel via the air handlers to occupied spaces.

SOLUTION: The building owner should use contractor specifications requiring the blocking or disconnection of the construction-affected HVAC systems before such activities begin. When HVAC isolation has been accomplished, it is important that the system be returned to proper working order after renovation activities.

7.Roofing All buildings with roofs eventually need roof repairs or replacement. The acrid odors of roofing tar are highly objectionable to many office workers, and when even a small quantity of such air is brought into a facility (indirectly from doors or other openings, or directly via outdoor air intakes), numerous short-term illnesses and health complaints can occur.

SOLUTION: The most obvious way to control roofing odors in occupied facilities is to temporarily limit all outside air into the building. Due to legal ramifications posed by employees complaining of potentially adverse health effects, supervisors might consider allowing employees voluntary use of personal time or sick leave to avoid these complaints.

In some IAQ situations, the solutions are not as clearly defined or as easily achievable as those described above. This is why an IAQ investigator should first rule out the simplest of explanations. Perhaps some of the above mentioned solutions can be tried as a means of eliminating problems. More complicated and less clearly defined issues may require the services of a certified industrial hygienist or consulting group specializing in IAQ matters.

Tim Ryan, Ph.D., CIH, CSP, RBP, is assistant professor at the School of Health Sciences at Ohio University in Athens, Ohio, where he teaches industrial hygiene and environmental health. He can be reached at: (740) 593-2134.

Sidebar

What pollutes indoor air?

By Stephanie B. Bowman

Three major factors that affect the quality of indoor air are:

1. Sources of contamination exist both inside and outside the building. Contamination coming in from the outside can be natural (pollen) or man-made (vehicle exhaust).

Other pollutants, such as asbestos, can release tiny, imperceptible fibers into the air, which if inhaled, can cause ailments ranging from chronic lung inflammation (asbestosis) to lung cancer.

Indoor air pollution can also be caused by leftover food and drink - all of which can harbor bacteria.

Indoor plants can also cause problems. While live plants help clean the air by absorbing contaminates, dead or dying plants sometimes shed microscopic particles that cause allergic reactions.

Water, too, is a potential source of trouble. Water damage on floors, ceilings or walls indicates that standing water is nearby - a perfect breeding ground for bacteria. And, if it is near a ventilation shaft, these bacteria can be drawn into the building's air supply.

2. Flaws in the design and operation of a building's heating, ventilation and air conditioning (HVAC) system can affect the quality of indoor air. Have certified technicians make regular inspections of these systems in your facility.

Without frequent cleaning and filter replacement, humidifiers and air cleaners can actually spread the pollutants they collect back into a building's work areas.

3. Employees who smoke are another major source of indoor air contamination. In fact, because of the dangers of cigarette smoke, the EPA recommends that every facility have a smoking policy that "effectively protects non-smokers from involuntary exposure to tobacco smoke." As a result, many facilities have created smoking rooms or designated outdoor smoking areas.

To combat indoor air quality problems, consult the Indoor Air Quality (IAQ) Guide published by the EPA and NIOSH. This Guide contains information on the prevention, identification and correction of IAQ problems.

Stephanie Bowman works in the production department for the MARCOM Group, Ltd. in Boothwyn, Pa. Information: (800) 654-2448.

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