Is My Building Sick?, Identifying the Causes

Is My Building Sick?

Identifying the Causes

To cure indoor air quality problems, you need to know what's causing them. The causes of most air quality problems can be identified by interviewing employees and conducting a thorough inspection of the building.

Occupants' symptoms can help you focus the search for the cause of indoor air quality problems. For example, if employees are complaining about a solvent smell, throat and eye irritation, and headaches, you are probably looking for a chemical being used nearby, a solvent spill, or something that is off gassing chemicals (figure 2). Knowing where and when the symptoms are experienced can provide clues to the source of the problem. For example, the chemical use, spill, or offgassing is probably occurring near the area where employees experience the symptoms or somewhere connected by air distribution. Inspecting those areas will probably reveal the cause of the problem.

Photo of a kitchen and dining area.
Figure 2—New cabinets, such as those in this bunkhouse,
are sometimes the source of chemicals that offgas,
contributing to poor indoor air quality and possibly causing
headaches or throat and eye irritation.

For smaller buildings, you often can pinpoint affected areas and identify symptoms simply by walking through the building and talking to occupants. In larger buildings, relevant information can be difficult to collect and track. A feedback form completed by building occupants can help an investigator obtain information. The "Indoor Air Quality Problem Fact Sheet" at the end of this report or another form can be used to gather information. Feedback forms should be completed by all building occupants, not just those who have complained of air quality problems, to obtain a complete picture of the problem.

Once you have learned the locations that appear to be affected and have an idea of the occupants' symptoms, you need to investigate the affected area. A small-scale drawing of the building's floor plan, such as a building evacuation map, can be used to record your findings. The table of "Common Symptoms, Causes, and Solutions to Indoor Air Quality Problems" at the end of this report contains information that can help you find the source of indoor air quality problems. More comprehensive information and tables are available in the "Diagnosing and Solving Problems" section of the U.S. Environmental Protection Agency's "Indoor Air Quality Building Education and Assessment Model (I-BEAM)" Web site at http://www.epa. gov/iaq/largebldgs/i-beam/text/diagnosing.html.

Use common sense and investigate thoroughly. For example, if occupants complain of a musty smell or have symptoms consistent with mold, look for places where mold might be growing. If the basement floor is wet and mold has begun to grow on the floor joists (figure 3), look for plumbing leaks. If you don't find plumbing leaks, look for ways that water could have entered the crawl space from outside the building, such as improperly adjusted irrigation sprinklers, slopes that funnel runoff to window wells, downspout discharges against a foundation wall, blocked foundation drains, and so forth.

Photo of floor joists with the text Mold and arrows pointing to the four different spots with mold.
Figure 3—The light and dark gray spots on these floor
joists are mold that could cause wheezing,
skin rashes, eye irritation, or other symptoms.

Over half of all indoor air quality problems are due to inadequate ventilation. When buildings are properly ventilated, contaminants are less likely to become concentrated enough to affect people's well-being. "Dilution is the solution to pollution" is an old saying with a lot of truth to it.

If the source of an indoor air quality problem is not evident, check the heating, ventilation, and air conditioning (HVAC) system for any of the following problems:

Air intakes are blocked.
- Air return grills are covered inside the building.
- Air intake vents outside the building are covered or misadjusted.
- Automatic dampers for air intake vents are not functioning properly.
The ventilation rate is inadequate for the number of people in the space.
- Appropriate ventilation rates are explained in the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standards 62.1 and 62.2.
- The recommended ventilation rate is 20 cubic feet per minute per person in most office areas.
- You can learn more about ventilation standards from the "More Information About Indoor Air Quality" section at the end of this report.
- Your facilities engineer can help you determine whether the ventilation rate is adequate.
Air filters have not been changed or cleaned recently or are not the correct type.
Air handlers and ducts are not clean.
Fumes such as those from shop work, office equipment, restrooms, or janitor's supply rooms are being pulled into the HVAC system through return air ducts rather than being exhausted directly outdoors.
Pollutants or irritants such as vehicle exhaust, pollen, mold, or welding fumes are being sucked into the building through the outside air intake or return air grills for the HVAC system.
Air pressure differences cause exhaust air or flue gasses to be drawn back into the building.
Slime or mold is growing inside a cooling tower, drip pan trays, or ductwork.
Accumulated deposits in boiler tubes, furnace flues, or piping prevent the efficient flow of combustion air, exhaust, or fuel.

Water is a common cause of air quality problems because mold will grow anywhere there is moisture and food (dead organic material such as fabric, dirt, particleboard, or lumber). If there has been recent flooding (especially in crawl spaces or other hidden areas), a leaky roof, or any other accumulation of moisture inside the building for a week or more, mold could be growing.

Objects inside your building could be offgassing chemicals. Formaldehyde and other gasses are often given off by new building materials, especially paint, glue, carpeting, and furnishings. Areas where solvents, glues, chemicals, or other hazardous materials are stored or used may not be properly vented. A can of solvent or other volatile material may have spilled.

If you can't find the source of the problem, contact your facilities engineer for assistance. Be sure to tell the facilities engineer what you've already done and the possibilities you have investigated. Your facilities engineer can conduct a more thorough investigation of the building's systems or conduct simple air tests. Chemical smoke tests can detect air movement that might indicate entry points of pollutants. Carbon dioxide and relative humidity test results can indicate potential problems. Your facilities engineer can also help you find a good industrial hygienist, if you need one.

An industrial hygienist can test the air in your building for hazardous substances. An experienced industrial hygienist also should be able to offer suggestions about where the pollutants may be originating and how they may be getting to the affected areas. An industrial hygienist's services are expensive, so hire one only when the hygienist's expertise is likely to help solve your problem.

No affordable test can analyze all the substances in the air. Even tests for individual substances or classes of substances can be expensive. One national forest spent $25,000 trying to determine the cause of symptoms affecting two employees. The tests provided no insights into the problem.

That's why it's important to do an investigation first— you need to have a reasonably good idea of what you're looking for before spending money on testing. Also, since most problems can be identified during an investigation, air tests are usually unnecessary. If you do a thorough investigation, you can usually spend your money solving problems rather than testing air.

It doesn't help just to know which pollutants are in the air. Even knowing the concentrations of pollutants may not help. Tests that can help solve problems include those that:

Compare concentrations of pollutants in different parts of the building and possibly the outdoors to help pinpoint sources of pollutants.
Check emissions from a particular piece of equipment to determine whether the equipment is the source of the problem.
Determine the concentration of compounds or conditions that identify a particular type of air quality problem.
- Carbon dioxide concentrations higher than 1,000 parts per million indicate inadequate ventilation of occupied areas.
- Carbon monoxide averages higher than 9 parts per million for 8 hours, or a 1-hour average higher than 35 parts per million indicate the presence of combustion gasses.
- Relative humidity higher than 50 percent may indicate inadequate ventilation, depending on outdoor conditions and whether the building has an air conditioning or dehumidification system. Mold is more active when humidity and temperatures are high.

Testing also can compare measured concentrations to exposure standards or public health guidelines for some specific pollutants. When deciding whether tests and comparisons will help you solve an indoor air quality problem, keep in mind that it is rare for these standards and guidelines to be exceeded in a Forest Service building. The exposure limits are established to avoid acute medical problems in industrial settings. Much lower exposure levels and milder symptoms are typical in office buildings with poor indoor air quality. You can learn more about pollutant guidelines and standards in the "More Information About Indoor Air Quality" section at the end of this report.