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Can the Air Be Cleared on IAQ?

April 28, 2010
Research shows a relationship between interior air quality and productivity, yet solutions are complex and often involve tradeoffs

As if anecdotal evidence weren’t sufficient, a growing body of research suggests that poor indoor air quality (IAQ) can have suffocating effects on office environments, resulting in reddened eyes, runny noses, and dips in worker productivity.

Lab studies performed by Lawrence Berkeley National Laboratory and others demonstrate that workers perk up when offending furnishings and finishes are removed from office environments, or when ventilation rates are increased to expunge pollutants.

Like stagnant air, the problem lingers, despite decades of emphasis on sick building syndrome, as well as more recent emphasis on green construction and stripping buildings of volatile organic compounds (VOCs), one of the agents contributing to poor IAQ.

There is neither a single cause nor a single remedy. Air quality can be adversely affected by microbial contaminants (mold, bacteria), gases (carbon monoxide, radon, VOCs), and particulates (minerals, soils, fibers) emanating from any number of sources, from intake and exhaust to carpet, paint, and coatings.

IAQ depends on the evaluation and coordination of multiple systems and processes. The Marietta, GA-based Greenguard Environmental Institute advises owners, designers, and builders to fashion an "IAQ Management Plan" or follow Greenguard guidelines encompassing everything from product selection, product installation, and ventilation to construction site management, scheduling, and installation sequencing.

It’s Best to Test

Product selection, construction site management, and installation sequencing are essential to reducing the presence of volatile organic compounds in office environments.

Because interior air quality (IAQ) programs can go awry, it’s equally essential to test the facility prior to occupancy to ensure that interior systems conform to specifications. The Marietta, GA-based Greenguard Environmental Institute advises owners to perform the following steps:

  1. Perform testing in accordance with standards issued by state and federal agencies, or by industry organizations such as ASTM.
  2. Perform testing during occupied hours.
  3. Operate the HVAC system at typical start and stop times, and with the minimal amount of outside ventilation specified by the project’s mechanical engineer.
  4. Perform one air sample per 25,000 square feet or for each contiguous floor area, whichever is greater. Include areas with the most and least ventilation.
  5. At each location, collect samples at 6 feet above the floor for a minimum of 4 hours.
  6. Demonstrate that contaminant concentrations don’t exceed maximum concentration limits.

The Tradeoffs of Material Choices
The details can be especially deviling when specifying interior finishes and systems, particularly paints and coatings, which are among the leading sources of VOCs in office environments. Although consultants commonly recommend water- or latex-based paints rather than solvent-based ones, even "low-emitting" products can contain VOCs as a result of biocides added to prevent mold growth, says Shannon Newton, industrial hygienist with Phoenix-based consultant Health Effects Group.

The good news is that some latex paints are available in low-biocide varieties, meaning they are 90 to 95 percent free of the preservatives and fungicides typically added to water-based paints to prevent mold and mildew. The bad: Mold and mildew may more easily encroach on biocide-free surfaces.

Oil paints don’t require biocides because they are naturally toxic to mold and mildew, but they contain high amounts of formaldehyde, among other VOCs.

The message is also mixed on commercial carpet. While there is little question that carpet emits VOCs – typically from adhesives required for installation or solvents for manufacture – the EPA insists there is no link between carpet emissions and health problems. Among the reasons: U.S. carpet systems don’t contain formaldehyde.

Somewhat counterintuitively, the EPA has worked with carpet suppliers to reduce xylenes, styrenes, and other VOCs. The Carpet and Rug Institute’s resulting "Green Label" program recognizes products that meet specified emission levels for styrene, PCH, and other VOCs.

Newton’s advice: Specify low-pile, vinyl-backed carpet. "It’s among the varieties that emit fewer gases than earlier generations’ materials," she says.

To further alleviate problems, Newton recommends water-based adhesives. The same goes for grouts, mortars, caulking, sealants, and similar products that can emit large quantities of VOCs.

A Sequence of Steps
In addition to materials that emit VOCs, there are materials that adsorb and re-emit them, creating a volatile relationship when one encounters the other. In new occupancies they needn’t, since many materials that off-gas – including paints, adhesives, sealants, glazing compounds, and composite woods – only do so for limited periods of time, according to Simon Turner, president of Fairfax, VA-based consultant Healthy Buildings International. These so-called Type One materials should be given time to dry or cure before Type Two materials – carpet, fabric wallcoverings, acoustical ceilings, upholstered furnishings, exposed insulation, and similarly porous products – are installed.

Alternatively, facility managers may opt for the "air out," in which VOC-emitting materials are unrolled in well-ventilated warehouses prior to installation. For wall systems, factory-applied paints or coatings are another option.

Despite these measures, circumstances may prompt owners to "flush out" the building prior to occupancy – an activity that forces large volumes of outdoor air through the facility for periods of 3 to 90 days, depending on outdoor temperatures. Recommended air volumes vary. At a minimum, the Health Effects Group advises owners to ventilate their buildings at a rate that produces 100-percent air change each hour.

Although owners can achieve LEED credits for a flush out, many building contractors and HVAC suppliers don’t recommend it, and with good reason, says Turner. "HVAC equipment isn’t designed for flush outs," he says. Among other problems, the flush out may overwhelm the system with moisture and particulates, leading to excessive mold growth.

Turner and others are promoting an IAQ test method as an alternative to the flush out. "Assuming that low-emitting products have been specified, there’s a good chance a facility will pass," he says.

A Time to Vent?
Although the best way to control VOC emissions is at their source, even resilient flooring and other environmentally friendly systems may emit gases, depending on how they are cleaned or treated. Likewise, the stuff of upholstered furniture – including polyurethane foam, adhesives, and thermoplastic rubbers – emit formaldehyde and other VOCs. Nor are solid wood alternatives entirely immune, because stains, waxes, and other coatings may emit VOCs.

Chief among the culprits are engineered wood products, which can off-gas for up to six months or longer, according to Newton.

The list goes on. Depending on the presence of other pollutants, including mold and carbon dioxide, building owners may have little choice but to address complaints with ventilation. ASHRAE currently recommends 17 cubic feet per minute (cfm) for offices, although a Finnish study of 400 workers in 14 mechanically ventilated office buildings indicates that outdoor ventilation rates below 32 to 53 cfm increase the risk of problems.

France requires buildings to supply ventilation in amounts three times that of U.S. buildings. However, French studies show that increasing the supply of outdoor air doesn’t necessarily reduce worker complaints.

In the United States, office buildings are awarded LEED credits for exceeding the ASHRAE standard by 30 percent. Depending on the equipment, owners again run the risk of overtaxing their HVAC systems, thereby undermining efforts to improve IAQ, says Turner.

Varying findings and recommendations among jurisdictions may be a function of several factors, including building location, according to Newton. "Increased ventilation may introduce outdoor pollutants to work spaces if the building is sited in congested urban areas, such as New York," she says. Occupancy is another issue. "If office space is overcrowded, excess carbon dioxide becomes a problem."

In good times, the majority of building owners are more than willing to comply with ASHRAE ventilation standards. In bad, some aren’t, says Newton. "It tends to cycle, depending on the economy."

Green initiatives to reduce energy consumption may further confuse the issue. Turner acknowledges that owners must strike an appropriate balance between health and environmental concerns.

Those that don’t, he says, "are being penny wise and pound foolish."

John Gregerson is a contributing editor from Chicago.

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