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 outdoor​s. 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.)
RESOURCES 60 Minutes: Lumber Liquidators Linked to Health and Safety Violations” (March 2015).
AIHA: "Technical Guidance on Laminate Flooring Outgassing" (2015). American Journal of Public Health: “Formaldehyde-Related Complaints of Residents Living in Mobile and Conventional Homes” (March 1987). California Air Resources Board and Office of Environmental Health Hazard Assessment: “Air Toxicology and Epidemiology." California Air Resources Board: “Formaldehyde” (July 2015). California Air Resources Board: “Ventilation and Indoor Air Quality in New Homes” (November 2009). Health Canada: “Formaldehyde in Indoor Air." World Health Organization: Air Quality Guidelines for Europe, 2nd Ed. (2000).
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.
UNDERSTANDING TEST RESULTS Currently, there is no regulatory standard for formaldehyde concentrations in residential settings. One way to view an indoor air formaldehyde measurement is to compare it to levels found elsewhere. A 1987 study of 891 U.S. homes published in the American Journal of Public Health found a correlation between formaldehyde and reported health complaints in about 2,000 individuals. At concentrations below 100 ppb, only 1-2 percent of occupants reported eye irritation. When the exposure level was at 100 ppb, 12 percent of occupants complained of eye irritation; at 300 ppb the percentage rose to 32 percent. At concentrations of 300 ppb, more than 90 percent of home occupants reported nose and throat irritation.
A 2009 study of 108 recently built homes in California reported formaldehyde concentrations ranging from 3.9 to 111 ppb, with a median of 29 ppb. Most new homes in the study (67 percent) had outdoor air exchange rates below the minimum code requirement of 0.35 air changes per hour (ACH). Inadequate ventilation of homes may be a significant factor in the buildup of formaldehyde and should be examined if levels are found to be elevated.
The World Health Organization has set a guideline level for formaldehyde in non-occupational settings at 100 ppb for 30 minutes. This guideline was developed to protect against sensory irritation in the general population, but WHO states that it also represents an exposure level at which there is negligible risk of upper-respiratory tract cancer in humans.
Health Canada has a residential indoor air quality guideline of 100 ppb for short-term exposure based on a one-hour average to protect against irritation of the eyes, nose, or throat, and a long-term exposure limit of 40 ppb based on a minimum 8-hour average, to protect against respiratory symptoms in children with asthma.
The California Office of Environmental Health Hazard Assessment established guideline indoor concentration values for formaldehyde, recommending an indoor concentration of no more than 7 ppb for longterm chronic exposure and 45 ppb for acute one-hour exposures to formaldehyde. These exposure guidelines were established for non-cancer irritant effects (eyes, nose, and respiratory system), with consideration for sensitive individuals as well as safety factors. However, more than 90 percent of the recently built homes in the California study exceeded the 7 ppb chronic exposure guideline, and 25 percent exceeded the 45 ppb one-hour exposure guideline, so the recommended levels are below ambient levels found in most homes. It would be unusual to find concentrations of formaldehyde below 4 ppb in most homes. Indoor concentrations of formaldehyde above 100 ppb are also unusual and may warrant additional investigation. THE BOTTOM LINE AIHA recommends using a common-sense approach and considering ventilation to reduce formaldehyde levels. If exposure assessment, indoor air measurements, or material sampling are to be performed, AIHA recommends use of trained and experienced professionals because of the need to select appropriate and validated methods, accurately collect samples, implement effective quality assurance and control methods, package and prepare samples for shipment to a certified laboratory, and interpret the results. Multiple sources contribute to indoor formaldehyde levels; attributing formaldehyde levels to one source, such as laminated flooring, is not a simple or precise exercise and may require extensive testing and modeling. CATHERINE BOBENHAUSEN, CIH, Authorized GreenScreen Practitioner, is senior industrial hygienist at Vidaris, Inc. She can be reached at cbobenhausen@vidaris.com or (212) 689-5389 ext. 107.
Testing for Formaldehyde For building products in the U.S., emissions tests for formaldehyde (and other VOCs) are typically based on California’s Standard Method for the Testing and Evaluation of Volatile Organic Chemical Emissions from Indoor Sources Using Environmental Chambers, Version 1.1 (CDPH/EHLB Standard Method V1.1). This method sets the protocol for testing and evaluating building products, and uses California’s lists of toxic substances for vapor phase organic chemicals: carcinogens, reproductive or developmental toxins, and systemic toxins. (Download the full document as a PDF.) The standard method covers composite wood panels, insulation, floor and wall coverings, acoustical ceilings, paints, coatings and finishes, sealants, and adhesives. It recognizes the Business and Institutional Furniture Manufacturers Association BIFMA M7.1-2007 test method for office and school furniture (which often includes composite wood with the potential for formaldehyde off-gassing). It has instructions for pro​duct samples, emissions testing, indoor concentration modeling, and calculation of emission factors and estimates of formaldehyde and other VOC concentrations in buildings. Each product category is capped at one half the Chronic Reference Exposure Level (CREL) for each chemical. The exception is formaldehyde, which is capped at the current CREL of 7 ppb because formaldehyde’s CREL is already very low relative to typical background levels in air.
Attributing formaldehyde levels to one source, such as laminated flooring, is not a simple or precise exercise and may require extensive testing and modeling.
Acknowledgements: This article was prepared on behalf of the AIHA Indoor Environmental Quality Committee and draws extensively from the AIHA document "Technical Guidance on Laminate Flooring Outgassing."​​​​​​​​​ ​The following individuals contributed to the guidance:
INDIVIDUAL CONTRIBUTORS Bruce Fraser, PE Daniel Friedman Kathleen Hess-Kosa, CIH Elliott Horner, PhD J. David Krause, PhD, MSPH, CIH Cheryl L. Marcham, PhD, CIH, CSP, CHMM Francis J. (Bud) Offermann, PE, CIH Douglas Peters, CIH, CSP Edward Sobek, PhD John P. Springston, CIH, CSP, MS PEER REVIEWERS David O. Carpenter, MD Bob DeMott, PhD, DABT J. David Miller, PhD James Poole, PhD, CIH Lynn Wilder, PhD, CIH
Formaldehyde in Flooring
Testing and Sampling Guidance for IH Practitioners
(Editor's note: acknowledgements are listed at the end of this article.)