Walls, ceilings, and indoor air quality

Photo © BigStockPhoto/Art Korad
Photo © BigStockPhoto/Art Korad

By Rachel R. Belew
By its very nature, indoor air quality (IAQ) is fragile and fickle—easily disturbed by the most minute of changes to the built environment, whether during construction or occupancy. In fact, even the seemingly innocuous introduction of new products and materials, such as wall and ceiling assemblies, can damage indoor air quality and, as a result, create an unhealthy space for both contractors and occupants.

Common interior products and materials emit volatile organic compounds (VOCs), chemicals that volatize, or become airborne, at room temperature. VOCs often produce distinct odours (e.g. paint fumes), and inhalation exposure to these chemicals can trigger numerous short- and long-term health problems, including:

  • headaches;
  • nosebleeds;
  • upper respiratory irritation;
  • eye and throat discomfort;
  • nausea;
  • dizziness;
  • cognitive impairment;
  • reproductive and developmental disorders; and
  • cancer.

Understanding how the design/construction process can take this information into account is critical for ensuring optimal IAQ for projects.

Chemicals in Canada
The 1999 Canadian Environmental Protection Act (CEPA) regulates the manufacture, marketing, use, transport, and disposal of toxic chemicals, while the Pest Control Products Act (PCPA) regulates use of pesticides. The Canada Consumer Product Safety Act, which passed in 2010 as a replacement for the more lenient Hazardous Products Act, regulates toxic chemicals in consumer products. Nevertheless, according to a 2005 report by Environmental Defence, safety testing is not required for the vast majority of chemicals in commerce. (For more information, visit www.environmentaldefence.ca/reports/toxic-nation-report-pollution-canadians).

When CEPA was introduced, 23,000 chemicals that had previously been on the market were granted universal approval without having undergone any safety assessments, the report notes. It was not until 2006 that those chemicals were categorized based on their toxicity—even then, only 85 were deemed “toxic,” and 67 were considered “priority substances,” meaning they must undergo further evaluation within five years. The rest of the chemicals are categorized as not needing additional safety assessments.

The Environmental Defence report also notes that while approximately 300 new chemicals are introduced into the Canadian market each year, companies are not obligated to submit their chemicals for safety testing before they enter the market. Further, companies whose chemicals are already on the market are not required to conduct retroactive safety testing. The report also states products are not required to be evaluated for safety before they are introduced to the country. Rather, post-market evaluations are conducted only after Health Canada receives complaints or concludes there is a potential risk.

Some interior spaces, like this preschool, are likely to have occupants more sensitive to the risks that are associated with indoor air contaminants. Designers should take steps to ensure a safer project. Photo © BigStockPhoto/Barbara Helgason
Some interior spaces, like this preschool, are likely to have occupants more sensitive to the risks that are associated with indoor air contaminants. Designers should take steps to ensure a safer project.
Photo © BigStockPhoto/Barbara Helgason

Greater surface area, greater emission potential
A good rule of thumb for determining a product’s potential to emit chemicals is to consider its surface area. Generally, the greater a product’s exposed surface area, the more opportunity there is for chemical off-gassing. This is why the smell of a freshly painted room may seem more pungent than the smell of, say, a freshly painted barstool in the same space.

Indeed, flooring, paints, coatings, wallcoverings, furnishings, and cabinetry are the building products most commonly associated with VOC emissions—common examples include aldehydes, alcohols, and normal hydrocarbons.

Among the specific VOCs most frequently found are:

  • formaldehyde;
  • acetaldehyde;
  • phenols;
  • dodecanol;
  • undecane; and
  • dodecane.

The addition of paint and other surfacing materials can significantly widen the spectrum of VOCs present in the air.

However, the list of IAQ-offenders is far more extensive than just those product types alone. It includes:

  • adhesives;
  • sealants;
  • surfacing materials;
  • doors;
  • closet systems;
  • insulation;
  • soundproofing;
  • wallboard;
  • joint compound;
  • grout;
  • wallpaper; and
  • ceiling tiles.

Many of these products not only have a particularly high risk of off-gassing because of their chemical composition, but they also take up a lot of surface area in a given space.

Wall and ceiling systems, therefore, can contribute greatly to indoor air pollution if specifiers, builders, and contractors fail to be diligent about using third-party-certified low-emitting products and materials.

VOC emissions versus content
Unfortunately, the marketplace is teeming with confusion over how VOCs are measured and assessed for their health impacts—particularly when it comes to interior wall and ceiling paints. Many marketers tout their products as ‘low-VOC’ or ‘no-VOC’ simply because they comply with Canadian content regulations. However, these regulations apply to exterior—not interior—paints. (Visit www.gazette.gc.ca/rp-pr/p1/2008/2008-04-26/html/reg1-eng.html).

For example, Canada currently requires a VOC limit of 100 g/L in flat architectural coatings; for non-flat coatings, the limit is 150 g/L; and for high-gloss coating, the limit is 250 g/L. Such content-based regulations were developed with the intent of reducing outdoor emissions that contribute to the formation of ground-level ozone and smog. In other words, they do not address indoor emissions and human exposure. Since not all VOCs contribute to ozone and smog formation, products like ‘low-VOC’ and ‘no-VOC’ paints, adhesives, and sealants can still off-gas potentially toxic chemicals into the indoor environment.

There are also other ways that ‘low-VOC’ and ‘no-VOC’ paints can emit volatile organic compounds. First, resins, pigments, and other additives in the paint can off-gas. Second, chemical reactions between the paint and the substrate can occur during application, creating new compounds that could not have been identified during the paint’s content analysis. Third, VOCs can synergize (i.e. combine) with VOCs from other products in the space, creating new, and sometimes more potent, compounds.

Sink effects and pollution migration
Besides direct product off-gassing, one of the biggest threats to a building’s indoor air quality is what is known as the ‘sink effect.’ As chemicals from various products accumulate in the air, porous materials (e.g. carpeting, upholstered furniture, wallboard, acoustic ceiling tiles, and fabric wallcoverings) adsorb the chemical molecules, or gather them in a thin film. Over time, the materials will then re-release those chemicals into the air—sometimes as soon as within one hour. (See the December 2001 issue of Indoor Air [vol. 11, no. 4]). Given that VOCs can continuously emit from a single source for several weeks at a time, the sink effect can actually worsen IAQ by perpetuating the cycle of chemical release and re-release.

One of the ways to avoid the sink effect is through specifying third-party certified low-emitting materials, as discussed later in this article. Such products can greatly reduce chemical emissions in a built environment. Further, the fewest wet materials as possible should be used; they should also be installed after the dry materials. When this is unfeasible (as is often the case with interior paints, coatings, and sealants), one should specify only those products certified for low chemical emissions.

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