Indoor air quality, known as IAQ , and more broadly indoor environmental quality, began with a few cases of tight building syndrome and mushroomed into prominence due to cases of multiple chemical sensitivity and indoor mold contamination. Now, thanks to efforts from the Environmental Protection Agency (EPA), Occupational Safety and Health Administration (OSHA), American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), and the US Green Building Council (USGBC), we have a robust knowledge base for dealing with these important issues.
The EPA and OSHA have extensive information and guidance about indoor air quality at their respective websites. The information covers building systems, preventing problems, and troubleshooting with comprehensive guidance provided.
In addition, non-governmental organizations like ASHRAE and USGBC have augmented the science of indoor air quality. ASHRAE’s ventilation guide is considered an invaluable IAQ resource, especially regarding office and general workspace basic parameters. The USGBC Leadership in Energy and Environmental Design (LEED) program offers guidance for designing and building the new generation of green buildings with focus on occupant health and indoor air quality.
Even so, indoor air quality issues arise due to many different and common reasons. Here are a few examples:
- Poor preventive maintenance
- Broken belt on a crucial exhaust fan
- New furnishings and floor coverings
- Delivery vehicle parked near an air intake
As the “Safety Guy,” having dealt with IAQ issues for more than a couple of decades and studied the guidance documents, I have developed an air testing protocol that may help prevent many common indoor air quality issues. My recommended testing protocol is based on EPA studies and the USGBC LEED indoor air quality commissioning requirements.
It entails a survey (of the concerned area or as an overall preventive, the entire facility or building) for specific parameters and contaminants. It is performed with portable instruments, so data is available immediately in real time. It is straightforward and inexpensive, even if consultants are hired to perform the work. Most importantly, the data is compared to existing OSHA, EPA, ASHRAE, and LEED standards or other recommended guidance levels and related directly to occupational health conditions.
This indoor air quality survey starts by taking measurements of the classic four ASHRAE comfort parameters: temperature, relative humidity, carbon dioxide, and carbon monoxide. This is most easily done using a modern handheld IAQ meter such as the TSI Q-Trak™, or equivalent, which can measure these four parameters at once.
Temperature, relative humidity, and carbon dioxide are important indicators of HVAC system performance as well as occupant comfort. ASHRAE standard 62.1-2010 recommends ranges for these criteria. If these indicators are out of range, it could mean the HVAC system is out of balance or the amount of outside air is insufficient.
Carbon dioxide depends on occupant loading and tends to increase during the workday. If accumulation or buildup is noted, first verify the proper amount of outside air, then check the supply flows and distribution in the area. ASHRAE recommends that carbon dioxide levels be kept below the ambient level plus 700 ppm. The theoretical amount of carbon dioxide in outdoor air is around 350 ppm.
Carbon monoxide is introduced from combustion sources. The OSHA permissible exposure limit is 50 ppm, a level we should never come close to inside a building or research laboratory facility. The EPA and LEED recommend an upper limit of 9 ppm or 2 ppm above the ambient level, whichever is lowest. My experience indicates that if you see levels of carbon monoxide above a few parts per million, you should seek out the source and eliminate it.
IAQ contaminant survey
After checking the ASHRAE comfort parameters, I recommend evaluating common contaminant levels, dust or particulates, and volatile chemical vapors. The amount of particulates in the air indicates HVAC system performance and filter condition when compared to outdoor levels.
Measuring particulate or dust is more involved than measuring the classic comfort parameters, but state-of-the-art instrumentation such as the TSI Dust Trak™, or equivalent, makes it easy. Dust is usually measured in milligrams per cubic meter of air (mg/M3) and reported for a specific particle size, median diameter of 10 microns or less and designated PM10. Like carbon dioxide, dust levels are compared to both OSHA permissible exposure limits and LEED recommended criteria. For acceptable indoor air quality, we should never approach the OSHA PEL, which is 10 mg/M3). The amount recommended by LEED standards is 0.05 mg/M3). Typical ambient levels with normal activity are about half the LEED standard and indoor office spaces will usually be in the microgram per cubic meter range.
To evaluate the levels of volatile organic compounds (VOCs), handheld instrumentation is also used. My favorite, the RAE Systems ppbRAE™, is a non discriminating photoionization detector that measures hundreds of common VOCs and provides a “total” VOC reading in either parts per million or parts per billion in air. In typical office environments, these readings are the result of perfumes, colognes, and air fresheners. However, these sources do not compare to common commercial sources such as paints, adhesives, thinners, strippers, and lubricants. And, in research settings, there may be a multitude of chemicals in use. Therefore, VOC levels are very important given the many potential sources and serious health and safety consequences. The recommended level under LEED is less than 500 ug/M3). For comparison, I typically see background levels between 200 and 300, even in hospital and laboratory buildings.
One last contaminant to consider is formaldehyde, especially if your facility has undergone recent new construction or renovation, as formaldehyde is contained in many urea resins, insulation, plywood, particle board, adhesives, and textiles. In addition, given its use as a preservative and sterilizer, research labs should definitely include this parameter. However, real-time measurements necessitate the use of portable infrared spectrophotometers, which are expensive to buy or rent and take some expertise to operate correctly. I recommend calling an industrial hygienist that will likely use low-flow sample pumps with appropriate media with the analyses done by an accredited laboratory. For reference, the OSHA PEL is only 0.75 ppm and the LEED standard for indoor air quality is 27 ppb.
Above I presented the Safety Guy Protocol for regular IAQ assessment. I recommend performing this screening at least annually and more often if your facility has serious issues or lots of employee complaints. By surveying your indoor air quality regularly, you can find and prevent many common problems before they become serious.