Thermo-Desorption, Gas Chromato-What??

March 1, 2008

Clarifying and demystifying product emissions testing.

By Keri Luly, LEED AP

Have your eyes and throat ever been irritated after hours in a conference room? If you're part of the design world, there's no doubt you've frequently heard about offgassing products, volatile organic chemicals (VOCs) in our breathing spaces and other worrisome indoor air quality (IAQ) issues. In my last column, "The Chemicals We Live In," we explored toxicology and precautions about synthetic chemicals in our built environment, so you know that there is much to be concerned about.

You probably try to keep up with all the certification programs and green product directories that are marketing like crazy these days, but do you know what those product certifiers are actually certifying? Test results. More specifically, test results, along with a strict methodology for figuring out what and how to test so we can rely on the results.

The key is repeatability; results that come out the same each time the product is tested, so we know the results are believable. This issue, we're going to go behind the scenes to learn what the better quality testing programs have in common. They are not all created equal, but those that are driven by LEED® credits are the subject of considerable scrutiny. Here are some of the proper testing methods and considerations.

TEST WHAT?Of all those individual products that you ordered for your last project (because they carried certificates of greenness), how many of them were actually tested?

None. None of the carpet, none of the furniture, none of those items in that space went through testing. A mobile test chamber did not go to the factory where those items were made to test each one coming off the production lines. A test chamber was not set up near the job site to test those items before they were moved in, either. But that's OK. It didn't need to happen that way because a "representative sample" of those products was tested instead.

Not just any piece of product can serve as a representative sample. In the best of testing programs, the sample size (and other characteristics) is carefully defined by a set of standards, which are determined by a multi-stakeholder group of experts in a publicly transparent process based on careful research and experimentation. Representative samples of simpler products with few components are easier to define than those made up of many varied materials. In the latter case, careful parameters must be set and agreed upon (standardized) so each round of testing reaches comparable results.

That sample must represent the "worst case" scenario for possible offgassing, so that, if it is within the maximum allowed emission levels, all the products it represents will be as well.

How are those sample parameters chosen? In the case of office furniture (a complex product) and LEED-CI EQ 4.5 Option C, it took a study of 31 randomly selected office plans from North American office buildings and more than 5,000 sample workstations to figure out the most accurate "worst case" scenarios for the inhabitants of both open-plan and private office settings. A standard work environment was defined to not only include a standard workstation with a defined amount of exposed surfaces, but also all the related traffic areas and support spaces and the clean air ventilation rates as set by ASHRAE.

Once a standard workstation was identified, its components and the amounts of exposed surface area were defined. Whole workstations and/or component parts can then be tested.

Equally important to standardizing the representative sample is maintaining the manufacturing processes and materials that made it. New testing is required if the manufacturer changes manufacturing processes, materials in the product, or conditions in the factory that could impact the product (such as painting being done nearby).

Once standards are set to define a representative sample, then two more obstacles to repeatability appear: how to get the representative samples to the test chamber; and how to test them once they arrive.

Whatever the product or component being tested, there will be a defined size sample piece that must be sent to the testing laboratory. The item must be recently manufactured and promptly wrapped in a manner that keeps in the chemicals to be tested for so that they are still present when the item arrives at the lab. The material used for wrapping must be airtight to seal in the volatiles during shipment and the item must be shipped quickly to the lab. A detailed "chain of custody" form must follow the item to describe it and the handling procedures.

Once the sample arrives at the laboratory, it will be unwrapped and immediately placed into a small, medium or large stainless steel chamber, depending on the sample size-which is also standardized. Everything about the testing procedure is specifically defined, including the temperature, humidity, cleanliness, and volume of air that will move through the chamber once the sample is sealed into it. At specific time intervals, samples of the air inside the chamber are taken and analyzed by thermal desorption-gas chromatography/mass spectrometry and high-performance liquid chromatography. In other words, the volatile chemicals being emitted from the product are separated out and identified using very sensitive, high-tech equipment.

The emission rates for those VOCs are determined so we know how much is emitted per unit of area of product per hour.

TEST FOR WHAT?If you're sick and your doctor orders tests, you won't be tested for every possible illness known. Instead, testing is targeted at several specific, likely problems. The same is true for testing indoor air emissions, whether it is for an entire room or for a specific product. Chemicals that are likely to be problematic are tested for, as well as the materials that make up the product, the materials that hold it together, the materials and processes that manufactured the product, and knowledge gained by past experience. These sorts of clues are important.

What goes into a product isn't always guaranteed to come out as emissions since chemical reactions can occur while the product is in use (e.g., wet products like paints or adhesives drying and changing in chemical and physical structure as they do). Also important to emissions are physical characteristics of the product, like porosity. Dense materials (e.g., particle board) tend to be non-porous so they offgas in smaller amounts, more slowly over a longer period of time than porous products like fiberglass that allow volatile chemicals to escape (offgas) quickly.

For most interior products, there are several chemicals that are commonly emitted, so those are the ones for which USGBC/LEED technical committees have set maximum emission levels for the Indoor Environmental Quality category.

LEED sets the maximum amounts of emissions of those chemicals and the deadlines for emissions to drop below maximum allowable levels. We know that offgassing is typically strongest at first and decreases over time, but LEED sets deadlines for that to happen.

Our technical ability to test for chemical emissions has improved dramatically over the years. Correspondingly, our awareness has increased, driving our demand for products that emit less. Considering the amount of time we spend indoors at work and at home, we can all breathe deeper and safer. Don't forget to seek out those tested products when making choices for both places.


Keri Luly has elected to donate her monetary compensation for the articles she writes to an environmentally pro-active organization of her choosing. This issue, she has selected the Union of Concerned Scientists (UCS)-a nonprofit partnership of scientists and citizens combining rigorous scientific analysis, innovative policy development, and effective citizen advocacy to achieve practical environmental solutions. Established in 1969, UCS seeks to ensure that all people have clean air, energy, and transportation, as well as food that is produced in a safe and sustainable manner. Sound science guides their efforts to protect and improve the health of our environment globally, nationally, and in communities throughout the United States. Visit to learn more.

Keri Luly, LEED AP, is Allsteel's stewardship coordinator and regular contributor to EnvironDesign Notebook. She can be reached at [email protected].

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