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Guide to Indoor Air Quality
The quality of air can greatly affect the well-being of people in an environment. It is particularly important to monitor indoor air quality because poor ventilation or air contamination can cause illness. Learn more about the importance of Indoor Air Quality at PE Facts!
The quality of air in non-industrial environments, such as offices, is referred to as Indoor Air Quality (IAQ). Ever since the energy crisis of the 1970s, IAQ has become a major issue concerning building owners, managers and occupants. The recent increase in complaints about IAQ is due to the lack of ventilation in buildings in combination with a high level of indoor-generated pollutants.
Poor ventilation in buildings is a direct result of energy-efficient construction and the replacement of natural ventilation (windows) with mechanical ventilation. Indoor pollutants have multiplied due to the increased use of synthetic building materials, the use of cleaning products with heavy chemicals, and the increased use of office equipment.
Another contributor to indoor air pollution is mechanical ventilation equipment. It can be a source of bacteria, dust, mold and viruses. If the air intake is improperly located, it can contaminate the IAQ by bringing in outside pollutants.
The occupants in a building are another major cause of indoor air pollutants. Our metabolic processes are a source of many different volatile organic compounds—not to mention perfume, hair spray, deodorant and other products that add contaminants to the indoor air.
Tobacco smoke is one of the most controversial air contaminants. OSHA's proposed IAQ standard states that a designated area with separate ventilation must be provided in workplaces where smoking is allowed.
Results of Poor Indoor Air Quality
There are two types of illness that may come from indoor air contamination. Sick Building Syndrome (SBS) is a reaction to various low-level contaminants. The contaminants could be either biological (mold), chemical (formaldehyde), or physical (heat, humidity, and lighting). Headache, fatigue, nausea, eye irritation and respiratory irritation are all symptoms of SBS. Symptoms usually go away when the individual leaves the building for a significant amount of time, but may recur when they reenter it.
The second type of illness from contaminated air is Building Related Illness. This is a reaction to a single contaminant present in the indoor environment. Legionnaires Disease is a good example of Building Related Illness.
Building managers need to take any IAQ complaints seriously and deal with them in a timely fashion. These situations are often hard to diagnose and complicated to solve. Taking fast action can help prevent other occupants in the building from getting SBS, or from thinking they have SBS when they are really experiencing other forms of stress.
Mechanical Ventilation Systems
Mechanical ventilation systems are designed to take in outside air and mix it with a portion of the recycled inside air, condition that air (heat, cool, humidify), and then distribute it throughout the building. The National Institute for Occupational Safety and Health (NIOSH) found that over 50 percent of IAQ problems are due to poor ventilation.
Outside air is brought in to reduce pollutants that originate in the building. Insufficient circulation of outside air, whether it is from an improper design or just malfunction, can lead to a build up of contaminants inside the building. It can also add to the contaminant buildup if the air that is being brought in is already contaminated.
There would be fewer problems if only outside air was used to replenish exhaust air. The disadvantage of this is the cost. Due to the high expense, new ventilation systems are controlled by computers to ensure the most cost-effective blend of indoor and outdoor air. Proper maintenance can help keep the mechanical ventilation system functioning efficiently and it also helps keep contaminants low.
The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) has specific restrictions on the amount of outside air that must be brought in through ventilation systems. For example, office spaces require 20 cubic feet of outside air per minute per occupant while a designated smoking area requires a much higher 60 cubic feet per minute per occupant.
A good indication of ventilation problems is a high concentration of carbon dioxide. According to OSHA's IAQ standard, CO2 levels must remain below 800 ppm and should be monitored quarterly. Similarly, ASHRAE and NIOSH both indicate 1000 ppm as a sign of insufficient ventilation. The natural CO2 concentration outdoors is approximately 300 ppm. Note: 800 ppm or 1000 ppm of carbon dioxide is NOT a hazardous concentration, but rather an indicator of potential ventilation problems. OSHA states that a CO2 level of up to 5000 ppm is still tolerable without being dangerous.
Since there are an innumerable amount of contaminants that can cause trouble, IAQ problems are very difficult to identify and solve. A combination of stressors (chemical, biological and physical), is usually the hardest to recognize. An IAQ investigation starts with thorough research and investigation at the site of the problem. The flowchart below shows just one possible approach to an IAQ investigation.
If it is necessary to monitor the air, relative samples from non-problem areas of the building can be useful in determining what the possible contaminants are.
The following is a list of building contaminants and the type of equipment that can be used to monitor and classify each one:
| Contaminant/Stressor | Monitoring Equipment |
| Air Speed | Anemometer |
| Lighting | Light meter |
| Heat | Thermometer |
| Noise | Sound level meter |
| Humidity | Hygrometer |
| Bacteria, virus, mold | Andersen Air Sampler |
| Volatile organic compounds | Photo Ionization Detector (PID),sampling pump and collection media, dosimeter badges and colorimetric tubes, specific colorimetric tubes |
| Dust and other particulates | Collection media and sampling pumps |
| Carbon dioxide | Colorimetric detector tubes, electronic monitor |
Note: This is not intended to be a complete list of contaminants.
Commonly Asked Questions
Q.When is the final IAQ standard expected?
A.The topic of air quality is extremely controversial and they have received a lot of feedback on the initial proposed standard. A final standard is not expected to be completed anytime in the near future.
Q. Does OSHA have definite restrictions for contaminants in non-industrial environments?
A. The current acceptable limit of exposure applies to both industrial and non-industrial environments.
Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.
