Editor's note: this article was updated Nov. 14, 2015, to correct an error regarding Health Canada's residential indoor air quality guideline for short-term exposure to formaldehyde. The guideline is 100 ppb.
In March, the CBS News program 60 Minutes aired a 
segment about allegations that Lumber Liquidators had sold flooring manufactured in China that contained high levels of formaldehyde. The segment addressed concerns about formaldehyde and the labeling of laminated flooring products manufactured in Asia, and served to illustrate the implications for indoor air quality of today’s global sourcing 
of building materials. In response to media attention resulting from the segment, AIHA created an online Formaldehyde Resource Center, including FAQs, a fact sheet, and technical guidance on laminated flooring outgassing. This article summarizes the technical guidance for IH practitioners. THE BACK STORY Formaldehyde is a volatile organic compound (VOC) or gas that is typically identified indoors at low levels, but usually at higher levels than outdoors. Formaldehyde is synthesized for use in binders, plastics, and preservatives. It is also used as a disinfectant or antimicrobial agent in cosmetics, as medical treatment for some skin conditions, and as a tissue preservative for pathologists and embalmers. Formaldehyde’s main use is in resins (urea formaldehyde, phenol-formaldehyde, polyacetal and melamine-formaldehyde). Formaldehyde resins have many benefits: low cost, fast curing time, dimensional stability, hardness, and a clear glue line. Composite wood—panels made from chips, particles, fibers, or pieces of wood bonded together with a resin—also contains formaldehyde. Examples of composites include hardwood plywood, particleboard, medium density fiberboard, thin medium density fiberboard, and furniture and other finished products. Composite wood is found everywhere: in wood flooring and underlayment, in solid doors, cabinetry, flooring, moldings, baseboards, shelving, and countertops. Formaldehyde is also found in other building materials such as insulation, glues, adhesives, furnishings, and finishes, as well as in cigarette smoke. For sustainable design architects, formaldehyde is a chemical to avoid. It’s classified as a known human carcinogen (Group 1) by the International Agency for Research on Cancer. It’s on the “red list” of the International Living Future Institute’s Living Building Challenge. It has a very strict Chronic Reference Exposure Level of 7 parts per billion in air, according to California’s Office of Environmental Health Hazard Assessment. At elevated levels, it can cause eye, throat, or skin irritation, allergic reactions, and respiratory problems like coughing, wheezing, or asthma. In response to indoor health concerns, California’s Air Resources Board set formaldehyde limits in 2007 for all composite wood sold or supplied to California. California’s “Airborne Toxic Control Measure to Reduce Formaldehyde Emissions from Composite Wood Products” has gained surprisingly widespread recognition, both in the U.S. and abroad. California’s Composite Wood Products regulation impacts a market of 2.5 billion square feet per year. It is one of the most stringent regulations around. To meet Phase 2 of the regulation, manufacturers use modified urea-formaldehyde, no-added formaldehyde (NAF), or ultralow-emitting-formaldehyde (ULEF) resin systems. An NAF product uses resins from soy, polyvinyl acetate, or methylene diisocyanate. A ULEF product uses melamine-urea-formaldehyde, phenol formaldehyde, or resorcinol formaldehyde resin. (While these new resins are good at cutting formaldehyde, they may not resolve everything. According to EPA, isocyanates such as MDI cause work-related asthma; some call this a regrettable substitution.)
Facts about Flooring Made with Composite Wood Products” (PDF). GUIDANCE FOR HOMEOWNERS In response to homeowners’ concerns about formaldehyde emissions from laminated flooring, AIHA suggests a common-sense approach. Adding or increasing outdoor air ventilation can substantially improve indoor air quality, assuming there is a clean source of outdoor air. Combined with balanced ventilation design or a heat-exchanger fresh air system and filtration, this approach can address many indoor air quality issues. Additional guidance can be found at the AIHA Formaldehyde Resource Center. GUIDANCE FOR INDUSTRIAL HYGIENISTS While testing of a laminated flooring product to determine compliance with CARB’s emissions standards is normally performed by qualified laboratories using specially designed chambers—see the sidebar for more information—homeowners might ask industrial hygienists to conduct air sampling for formaldehyde once flooring has been installed. AIHA does not prescribe if or when a home should be sampled for formaldehyde. However, its technical guidance outlines issues to consider when sampling is performed:
  • Have some or all of the occupants begun to exhibit symptoms consistent with exposure to elevated levels of formaldehyde (for example, eye, nose and throat irritation; nasal stuffiness; and allergic reactions, including increased respiratory symptoms in asthmatic children)? If these symptoms are observed soon after a new building product has been installed, or after moving into a new home, individuals should seek medical advice and may wish to consider whether a link exists between their home and their symptoms.
  • Many indoor pollutants can cause these same symptoms. The industrial hygienist should not ignore other potential exposures even if the initial request focused on formaldehyde.
  • If the symptoms appear to be associated with emissions from building materials, and the materials likely contain formaldehyde, testing should be performed using only validated methods.
AIHA does not recommend specific sampling devices, methods, or laboratories. It does recommend that industrial hygienists use only laboratories demonstrating ISO/IEC 17025:2005 accreditation for testing through an accreditation body fully recognized by the International Laboratory Accreditation Cooperation (ILAC). These accreditation bodies are listed on the ILAC website. (If the laboratory is accredited by AIHA Laboratory Accreditation Programs, LLC, the laboratory should be listed under the Industrial Hygiene Laboratory Accreditation Program.) Also, the industrial hygienist should review the body’s scope of accreditation to document that the laboratory uses suitable instrumentation and test methods for analyzing formaldehyde in air samples. The industrial hygienist should prepare a sampling plan and strategy that supports the goals of the assessment and explain the plan to the homeowner before collecting samples. Measurement methods to quantify formaldehyde concentrations should be sensitive enough to detect concentrations in the range of 10 ppb or lower. Direct-reading field instruments are not typically designed with this level of sensitivity. When sampling for formaldehyde, any known interferences should be avoided or accounted for. For example, phenol can bias sample results upward, whereas ethanol, cyclohexanone, and aromatic hydrocarbons have been reported to produce negative interferences with the NIOSH 3500 method. Sample collection methods commonly used to measure total VOCs, such as TO-15 evacuated stainless steel cylinders and others used to measure level reactive compounds, are not efficient collection methods for carbonyl compounds and can underestimate formaldehyde levels. Field sampling methods (for example, ASTM D5197 or EPA TO-11A) use adsorption onto 2,4 dinitrophenylhydrazine (DNPH) solid media. Active samplers use sample tubes and cartridges that contain silica gel impregnated with DNPH. Passive DNPH samplers are typically hung securely a minimum of 12 inches from any surfaces for 1 to 2 days while keeping all windows closed. The passive samplers are started and stopped by simply uncapping and capping the inlet cover, while recording the start and stop date/time. The samples should be mailed to an accredited laboratory with chain-of-custody for analysis by high-performance liquid chromatography (ASTM D5197). Careful documentation of environmental conditions and use of quality control and quality assurance measures are key. Carrying out testing with the windows closed will provide a typical worst-case scenario, better suited to determining the presence of formaldehyde sources and less suited to determining occupant exposures.
Formaldehyde in Flooring
Testing and Sampling Guidance for IH Practitioners
(Editor's note: acknowledgements are listed at the end of this article.)