Most Americans spend 90 percent of their time indoors. During the energy crunch of the 1970s, owners minimized the amount of air infiltration through their building envelopes and then reduced the quantity of outside air used for ventilation as just two more ways to conserve energy. In some cases, these measures that saved energy dollars compromised the health of the workplace.
According to The Occupational Safety and Health Administration, sick building syndrome affects 30 to 70 million workers in the U.S. Common sense tells us that we can achieve higher levels of worker efficiency to the extent that we improve the environment and tools that workers have at their disposal. The many companies that assert "people are our most important asset" should take appropriate measures to preserve, protect and nurture those assets.
Common symptoms
Sick building syndrome is the term used to describe the phenomenon wherein groups of people exhibit health problems that seem to be related to how long they stay in a building, but there is no specific cause for the malady. The constellation of symptoms that indicate a building might be causing suffering for the people that must work there include:
- Sinus pain.
- Hoarseness.
- Cough.
- Sore throat.
- Burning eyes, nose.
- Fatigue.
- Difficulty concentrating.
- Headache.
- Aching muscles, joints.
- Dry, itchy skin.
- Sensitivity to odors.
One distinguishing characteristic of sick building syndrome is that the symptoms do not clear up spontaneously in a matter of days, as one would expect if they were attributable to a normal ailment. If the symptoms vanish after a two-week vacation but reappear upon returning to work, it may indicate that there is a problem with the building's environment. Of course, it is important to distinguish between sick building syndrome and problems caused by high population density in the workplace. For example, people in close proximity can continually re-infect each other with a common cold or similar ailment.
The appearance of symptoms may not affect the entire work force universally. In most cases, only those people with a sensitivity to the causative agent(s) exhibit the symptoms. Complaints may be connected with only one room or section of the plant. In any case, The Americans with Disabilities Act protects workers affected in this way from harassment and discrimination in job assignments and promotions.
After eliminating possible objective causes, such as noise, inadequate lighting, uncomfortable temperature, high humidity, ergonomics and other physiological stressors, what remains may be a genuine case of sick building syndrome. One study of the subject concluded that the symptoms are associated with increased concentrations of nitrogen dioxide, total volatile organic compounds and dust, among other things.
Causes include building systems not being operated in accord with the original design specifications, defective building design and activities of the occupants. Inadequate ventilation is thought to contribute to the problem. The total flow of fresh air moving through the ventilating system may be acceptable, but if that air is distributed badly, indoor air quality may suffer. AHSRAE's [I]Standard 62-1989: Ventilation for Acceptable Indoor Air Quality[I] is a voluntary standard that specifies minimum airflow (15 to 60 cfm/person), depending on the activity taking place in the space.
Life is ubiquitous
You should have no doubt that pollen and microbial life forms are infesting your HVAC ductwork, living on your office carpets and thriving in the dust clinging to the rafters in the plant. Because life depends on moisture and suitable temperatures to propagate, inefficient HVAC control systems can provide both to the opportunistic microscopic plants and animals that make people miserable.
Also, offices are filled with plastics, adhesives, residues of cleaning agents smeared on desks, manufactured wood products and other items that release volatile organic compounds. The source of contaminants also can be located outside the building. If the rooftop air handling unit is introducing contaminated air into a controlled environment, no amount of ventilation adjustment will solve the problem.
Flora as a solution?
According to advocates, some types of greenery appear to be able to convert airborne contamination into innocuous substances and plant tissue. Others argue that it is really the bacteria in the soil that consumes the contamination. Still other researchers can show that, yes, plants clean up the air, but only in controlled laboratory experiments.
It is doubtful that a few dozen contamination-consuming plants placed strategically in the office will eliminate complaints and physical symptoms. Some researchers estimate that achieving even a minor degree of improvement in this way would require several hundred plants in an office or cubicle, assuming that people don't stir up contamination by moving around and certainly not admitting fresh contamination by opening doors. Growing plants simply are aesthetically pleasing.
Mechanical purification?
Many offerings in the marketplace claim to clean and purify air and mitigate the sick building syndrome. Ionizers are intended to remove pollutants having a positive charge, but the distribution of ions from the units is non-uniform and the devices are not capable of removing all varieties of contamination. Ozone generators are intended to oxidize contamination molecules, but the relationship between ozone and smog, and the health effects of breathing ozone means these devices are probably not suitable for an office setting. Electrostatic precipitators remove suspended solids in the air, but they don't have any effect on vapors that may be contaminating the environment. HEPA filters remove suspended solids, including bacteria, most effectively, but the filters don't stop vapors. Activated carbon removes the vapors, but doesn't materially affect the suspended dust particles in the air.
Investigating complaints
The idea is to find the root cause of the IAQ problem, not simply identify the contaminants affecting the people working in the area. Treat this as an engineering problem. Get the lay of the land and gather background material with a literature search. This is especially easy if done online. Identify and collect the applicable IAQ standards. Don't forget to check the local building codes.
Take a tip from journalists and determine the who, what, why, when, where and how when tracking IAQ complaints. Enlist the assistance of the people on the plant floor and in the offices. Be sure that they understand their activities affect the quality of the air in the workplace.
Walk through the problem area to gather intelligence. The people in the area should know beforehand that the investigation is happening. During the visit, make notes regarding the occupants, the condition of the HVAC system, sources of contamination and pathways for contamination coming from areas of high pressure to areas with lower pressures. Talk to the people working in the area. They are closest to the problem and probably have a good idea about the source. Apply the scientific method to finding a solution to the problem; it avoids a knee-jerk reaction that may be completely ineffectual. The scientific method consists of a few simple steps:
- Observe the phenomenon.
- Invent a hypothesis consistent with what you observe.
- Use the hypothesis to make predictions.
- Test the predictions by experiments or further observations.
- Modify the hypothesis in the light of your results.
- Repeat to eliminate any discrepancy between theory and experiment or observation.
An iterative application of the method will allow you to zero in on the root cause of the problem in an objective manner.
Sh:Solutions
You want the IAQ solution that imposes the lowest total cost. For example, there is no point in making major changes to the HVAC equipment and duct routing if the root cause is a mildewed carpet, chemicals slowly evaporating from a residual film of cleaning agent, or dirty filters in the air handling unit. If testing your hypothesis includes quantifying the concentrations of airborne particulates and vapors, there are monitoring devices that will tell exactly what you need to know to make a decision. When you start a measurement program, however, be sure that everyone affected by the problem understands that it takes time to conduct a proper measurement program.
There are several possible measures that can eliminate or reduce the problem of sick building syndrome. The easiest is to remove the root cause. Use a different cleaning agent, use reformulated chemicals in the manufacturing process, relocate the solvent cabinet and take any other measure that is relatively easy to complete. Adjust the ventilation rates to reflect either the design values or the ASHRAE minimums, whichever is greater. Open the windows.
If you must start working on the HVAC system, you could start by cleaning the ducts. One drawback to duct cleaning is that, by itself, it will probably not eliminate the symptoms.
Additional resources
Being able to discuss IAQ issues intelligently requires knowing the precise meaning of many technical terms. The Environmental Protection Agency offers a glossary of terms at www.epa.gov/iaq/glossary.html.
By the time you read this, The American Society of Heating, Refrigerating and Air-Conditioning Engineers will have finished taking public comment about a proposed standard for indoor air quality in residences. [I]Standard 62.2P, Ventilation for Acceptable Indoor Air Quality in Low-Rise Residential Buildings[I], does not directly address the industrial situation. A new publication from the same organization, however, is more on point. Intended to put control of indoor air quality into the hands of building operators, [I]Application Guide: Indoor Air Quality Standards of Performance[I], helps plant professionals understand how operation and maintenance procedures affect IAQ. The book is available from AHSRAE at 404-636-8400.
The Building and Fire Research Laboratory at the National Institute of Standards and Technology recently released a public domain computer simulation program for multizone airflow and air quality analysis. Called CONTAMW 1.0, the simulator can determine a building's infiltration rate, calculate the dispersal of airborne contaminants, predict the exposure of building occupants to contaminants. The Windows-based software can be downloaded at www.bfrl.nist.gov/863/contam.
Should you decide that it is necessary to clean the HVAC ductwork, The National Duct Cleaners Association offers a general specification that describes the minimum requirements for cleaning commercial ductwork. Of course, the spec must be modified to include your site-specific information. The document is available at http://nadca.com/spec/nadcspec.htm.
Building Air Quality: A Guide for Building Owners and Managers is a 229-page book that is available online from The National Institute for Occupational Safety and Health (NIOSH), the Federal agency responsible for conducting research and making recommendations for the prevention of work-related disease and injury. The book is found at www.cdc.gov/niosh/pdfs/iaq.pdf.
Department of Medical Sciences at the Faculty of Medicine of Uppsala University, Uppsala Sweden posts details of how to conduct an investigation of suspected sick building syndrome at www.occmed.uu.se/indoor.html.