TVOC or not TVOC?

1. On the Building Ecology web site you will find a commentary from Al Hodgson. I believe it addresses the TVOC question you are writing about. I have pasted it in below. You can access it directly on the home page http://www.buildingecology.com. It points out many of the limitations of the TVOC limit as a means of protecting building occupants.

2. In important and relevant news today, WHO Europe has just released the IAQ Guideline of Indoor Air Pollutants, a step in the direction of adopting pollutant limits relevant to exposures in indoor air. The announcement and the link to the freely downloadable full publication can be found at http://www.euro.who.int/en/what-we-do/health-topics/environmental-health...

3. My own view is that while there are significant gaps in what is covered by the limit values for chemicals emitted from many important indoor sources, the extension of the use of TVOC undermines attention to this problem and reduces or removes the potential motivation to address the gaps. A process should be initiated to fill the gaps. There are many models available such as those followed by a number of public agencies at the national, state and even international level.

I suggest consideration opf the processes followed by the California EPA's Office of Environmental Health Hazard Assessment could be adopted by a range of groups including CDC's ATSDR and NIOSH, EPA's Office of Air Quality Planning and Standards and EPA's IRIS program, and California's Air Resources Board. There are a couple of ASTM standards adopted by Committee D22 and its Subcommittee D22.05 on Indoor Air that provide some models for exposure models (bedding sets) and development of criteria for standards (aircraft cabins).

I believe that EPA's Office of Indoor Environment could and should facilitate a process to develop voluntary consensus standards, as authorized by a Federal government Executive Order. It can do this without developing or adopting them itself, as it does with many ASTM standards, ASHRAE standards, and many other building code and environmental standards and guidelines . This could be done through ASTM or through the formation of an independent group, somewhat similar to the Carpet Policy Dialogue of the early 1990s. The advantage of doing it through ASTM is that it is an open, consensus-based standards developer that does not itself do testing or certifications on the basis of the results. This contrasts with Underwriters Laboratory, USGBC, Greenguard/AQS, and NSF/GGEI which all are involved both in development of standards as well as either testing and/or certification. It might also be considered as an activity for ISIAQ, the International Society for Indoor Air Quality and Climate and its Academy of Fellows.

4. Here is the commentary by Al Hodgson, now on the BuildingEcology.com web site.
Moving Beyond TVOC - Reasons to avoid the use of TVOC as Pass/Fail criterion for assessing VOC emissions from products
by Al Hodgson, Co-founder and Research Director, Berkeley Analytical Associates

Total Volatile Organic Compounds (TVOC) has a long history as a metric for determining the acceptability of the emissions of VOCs from building products and furnishings. The first significant program to rely on a TVOC criterion was the Carpet & Rug Institute’s (CRI) Green Label Program that evolved out of the Carpet Policy Dialog between the carpet industry and the US EPA.The TVOC criterion was later incorporated into the U.S. Green Building Council’s LEED rating systems and was adopted by the commercial furniture industry. More recent VOC emission test method and acceptance standards have focused instead on individual VOCs that may pose health hazards to individuals at low concentrations. Examples of such programs in North America are the California Department of Health Services' Standard Practice (a.k.a. Section 01350), which recently was revised to Standard Method Version 1.1, and CRI’s Green Label Plus program. TVOC values are still reported, but pass/fail determinations are based on the emission levels of individual compounds of concern. There is an urgent need to expand such determinations of acceptability beyond a select number of individual VOCs to encompass the broader range of chemical emissions that may impact health. TVOC is again being proposed to fill this gap and may be appealing to many because of its presumed simplicity. In my opinion, we should avoid this temptation and move on the more difficult, but certainly achievable, task of focusing on the toxicity of individual compounds. The following are my primary arguments against the use of TVOC as a Pass/Fail metric.

TVOC measurements may be grossly inaccurate and therefore the TVOC concept is unsuitable as a PASS/FAIL metric. Individual compounds' instrumental responses relative to toluene, the surrogate standard of choice, vary dramatically. Some common VOCs have an order of magnitude lower response per unit mass than toluene. Other compounds have higher response ratios. Even within a class of compounds (e.g., alkane hydrocarbons) the response per unit mass can vary substantially depending upon their chromatographic retention times with early eluting compounds having lower response ratios than late eluting compounds. Individual VOCs also are measured with very different levels of precision. Thus, there is no way to determine the accuracy and precision of TVOC measurements made across different mixtures of VOCs characteristic of the broad range of products and materials being assessed. This problem with TVOC is well recognized by true experts. In particular, ISO 16000-9, the emission test method most widely used in Europe and other regions outside of the US clearly states. "The sum of emitted compounds, TVOC, should be regarded only as a factor specific to the product studied and only to be used for comparison of products with similar target VOC profiles." One of the big changes that is needed in the reporting of VOC emissions is to include estimates of uncertainty. In fact, reporting of uncertainty is dictated by ISO/IEC 17025 quality management systems if requested by the customer. The use of TVOC moves the process in the completely opposite direction toward unknowable uncertainty.

Product certification programs can, and should, be progressive with respect to public health concerns. TVOC may be a useful tool for such certification programs. For example, the monitoring of TVOC for a specific product over time (in keeping with the ISO 16000-9 precaution) may provide useful information on manufacturing variations within or among production facilities assuming the VOC profiles are similar. However, this is not a substitute for assessing the potential impacts of the individual compounds comprising these emissions. There are many different lists of toxic chemicals that can be used by certification programs as the basis for such assessments. The fact that a publically available method and guideline document only contains a relatively short list of chemicals of concern should not be a limiting factor. MBDC's Cradle-to-Cradle program is one example of a proactive certification program that considers the environmental and human health issues associated with chemicals used the in the manufacturing of products. It should be noted that a significant downside to this particular program is the lack of transparency with respect to how the toxicology judgments are made. It also might be argued that the success Greenguard's Children & Schools program in the marketplace is, in part, related to their use of an expanded list of individual chemicals of concern.

Assuming there was a more accurate and precise measure of the quantity of total VOCs emitted by a product, there still is a need to establish an acceptable level. The Greenguard Indoor Air program uses a guideline of 500 µg/m3 modeled to a small room. The Greenguard Children & Schools program uses a guideline of 220 µg/m3 modeled to a typical school classroom. The 500-µg/m3 value has some historical precedence, but in reality these numbers are simply 'pulled out of a hat.' The chemicals used in manufacturing products are undergoing rapid change. When the TVOC metric was first implemented as a metric for the Carpet & Rug Institute Green Label program in 1989, the chemicals used in manufacturing included aromatic and chlorinated hydrocarbon solvents. Today in the 21st century, most products do not use these traditional solvents because of concern regarding their toxicity. Instead, we have an increasing emphasis on 'Green Chemistry' and widespread use of water-based solvent systems. Generally, these chemicals have lower toxicity than the solvents they are replacing but they also have lower vapor pressures. Due to their low vapor pressures, the off gassing of these solvents occurs more slowly than for aromatic solvents, for example. Thus, total VOC emissions will be higher, but in many cases toxicity can be presumed to be lower. The use of a TVOC metric may, therefore, penalize products and inhibit government's and industry's efforts to switch to more sustainable chemistry. These efforts are better served by focusing on the toxicity of the individual compounds.

US Proponents of TVOC have repeatedly pointed to European product testing methods and certification programs as a precedent for the use of TVOC. While it is true than many European programs do contain a TVOC requirement, the values are often considerably higher than the values the proponents would like to impose on the US. The most widely used European assessment document, the German AgBB (http://www.umweltbundesamt.de/building-products/agbb.htm) scheme, relies mainly on criteria for a list of about 190 individual chemical substances. The AgBB TVOC criteria at 3 days is 10,000 µg/m3, or 20 times a proposed 500 µg/m3 value measured at 7 or 14 days (note that a direct comparison is complicated by different testing methods and modeling assumptions, but the magnitude of the difference is approximately correct). Clearly the dominant European assessment criteria focus on individual VOCs, NOT on TVOC.

Proponents of TVOC argue that there are tens of thousands of individual chemicals emitted by building products and furnishings that may be affecting our health, and due to this overwhelming number only a metric like TVOC is practical. This is far from the truth. There are many hundreds of chemicals in petroleum distillate fractions, e.g., Stoddard solvent. Over the years, there has been a shift away from these solvent mixtures to simpler, manufactured mixtures with better controlled volatility and elimination of compounds that are of particular concern because of their toxicity. The true number of chemicals that are frequently emitted by building products and furnishings probably number several hundred. If this universe of chemicals can be identified (not difficult), it is a much more manageable task to evaluate the toxicology data to see which chemicals are of real concern for the general population and at what levels.

Proponents of TVOC also argue that there are many potential synergistic relationships among VOCs and that, again, only the use of TVOC can guard us against this danger. Such arguments regarding synergism are not founded on fact. For example, while the hedonistic value of odor response can vary depending upon the mixture of chemicals, odor receptors are very specific for particular chemical functionality and size. The mammalian sensory perception system (Trigeminal) is much more generalized. However, the effects for VOCs with low reactivity (i.e., most of the VOCs that are measured by conventional methods) have been shown to be additive in both animal and human studies. If there is a highly reactive VOC in the mixture, the sensory response is controlled by the reactive chemical, not the mixture.

Al Hodgson is Co-founder and Research Director, Berkeley Analytical Associates

I hope these comments are helpful.

For full disclosure, I am Manager of Science and Standards at GREENGUARD Environmental Institute.
TVOC is an important issue and requires further discussion to make sure we cover all the relevant information. A few important points to illustrate:
1) While the ideal way to measure an emitted VOC is by accurately measuring each individual VOC compared against a standard for that VOC, use of a surrogate such as toluene is widely accepted. I can point to numerous regulatory test methods that take this approach either when individual standards are cost prohibitive or when exposure to a chemical is too risky.
To be clear, TVOC can still be measured under standard conditions including: a. How much of the product (e.g., flooring) is present (e.g., m2). b. How much clean air ventilation is present (cfm or m3/h). c. Temperature, relative humidity, and other details. d. Time (days) after unpacking or installation before the limit must be met.
2). Use of TVOC is warranted especially when arguing for a risk management approach to controlling chemical exposure. I can most simply illustrate an argument for TVOC by referring you set of slides recently discussed in the early development phases of a health based emissions standard. The link to the power point is here.
http://standards.nsf.org/apps/group_public/download.php/10161/Tox%20Sess...
Slide 5 demonstrates the importance of TVOC. Most of the chemicals covered in the current version of LEED can be seen under “chronic_rel” in slide five. CRELs cover such a small number of chemicals (35) and TVOC covers in the near infinite number of chemicals found in indoor air.
3) While the US has not yet come to an agreement on TVOC, the rest of the world seems pretty consistent in their application of what is known as a “precautionary principle.” Use individual limits on known chemicals of concern and use a TVOC measure on chemicals that we don’t know about yet. Almost every EU low-emitting product standard, certification program, or government mandate requires both. Yes they are at different time points, but they USE both limits to minimize chemical exposure.
4) Other sustainable rating systems use TVOC limits for low-emitting products and building clearance levels (as LEED does in EQc3.2) and many countries have TVOC as a main component of their building clearance limits. While the measurement methodologies are different for product emissions and building air tests, they still are focused on the same thing – minimizing the total exposure to chemicals.
TVOC is already in the current proposed credit, it is just referenced sporadically instead of consistently. A TVOC limit is a requirement in the furniture credit and the AgBB standard for products in projects outside the US. I agree with Mr. Oppl that a limit of 500 after 14 days is reasonable and is a good solution to address this issue. It would provide an important backstop against high emissions of chemicals not covered by the 35 CRELs found in the current version of LEED.

I agree (with Hal) that that there are significant gaps in what is covered by the limit values for chemicals emitted from the many indoor sources. In no way should attention be diverted from that issue. While the use of TVOC in no way addresses the deficiencies in current limit values; in the absence of comprehensive exposure limits it does provide a protective measure against high level of indoor air pollutants not presently covered by existing limits. It is well known that TVOC is not linked with health outcomes, however a reasonable TVOC limit indicates that the risk for exposure to high levels of harmful emissions may be low.

Page 31 EU Report 27 makes the following recommendations with respect to TVOC.

“TVOC should not be used alone as an indicator for evaluating health effects from indoor material emissions”
http://www.product-testing.eurofins.com/media/1744366/ECA_report_no_27_f...

I don’t know of any group that advocates the use of TVOC without the use of additional criteria, nor would I support such an approach, but in the absence of a comprehensive set of definitive limits for indoor air pollutants, the use of TVOC in combination with other defensible limits of exposure such as CRELs serves its purpose.
As far as existing TVOC limits are concerned, the GREENGUARD Children and Schools TVOC limit was not “pulled out of the air.” It is the result of a body burden correction factor. This is outlined in the Children and Schools standard itself.

It is well know that many existing standards for indoor air quality have different TVOC limits. That certainly doesn’t argue against the use of TVOC, but rather says more discussion regarding what the TVOC limit should be is needed.

While I agree, that emissions from one product may consist of several hundred compounds, it is important to note that not every product will emit the same several hundred compounds. Different manufacturing processes are going to introduce different chemicals into products and while the elimination some solvent systems may help reduce the number of VOCs released, solvent systems are not the only potential source of VOCs.

I also agree that sensory effects for some chemicals is additive, however chemical synergy is a real concern and is difficult to address in current risk assessment approaches. In the absence of ways to addresses all of these issues, there is arguable reason to implement the use of a TVOC limit.

I'm the Research Director for Berkeley Analytical, an IAQ laboratory founded in 1989 that focuses on the testing of building products and furnishings for VOC emissions. I'm also the chairman of ASTM Subcommittee D22.05 on Indoor Air. I’ve waited a few days to comment as I contemplated how best to contribute to the discussion on the pros and cons of using TVOC as a metric for determining the acceptability of VOC emissions from products used indoors. Hal Levin already has posted some of my arguments against the use of TVOC. Here I thought it would be useful to point out some of the obscure history regarding the use of TVOC and also to introduce some authoritative opinions on TVOC from sources that are unlikely to join the forum discussion.

Firstly, I want to bring everyone’s attention to some little known facts surrounding the origins of the use of TVOC as a metric for determining the acceptability of VOC emissions from building products. The U.S. carpet industry represented in part by the Carpet & Rug Institute entered into an agreement with U.S. EPA and GSA to identify low VOC-emitting carpet floor covering products. The meetings and the research that were conducted in 1990 and 1991 are documented in the “Carpet Policy Dialogue, Compendium Report, September 27, 1991” published by the U.S. EPA and still available on the web. Although the TVOC metric was used as the basis for this study, there was considerable debate regarding TVOC and no clear consensus about its use was obtained. The dissenting opinion was presented in a minority report appended to the Compendium Report. Industry held the prevailing view and strongly promoted the use of TVOC and was opposed to full speciation of VOCs for two primary reasons stated as [my comments are shown in brackets]:

1. TVOC levels resulting from carpets are low and reporting of speciated data could lead to misinterpretation [i.e., such results might show the presence of benzene, toluene, styrene, and other know toxicants];

2. Release of speciated data could result in disclosure of confidential business information [i.e., manufacturers didn’t want their competitors to know about their processes].

Thus at its origin, the TVOC metric was used primarily as a means to obscure information that industry thought might be damaging to their interests. The following is the transcribed text of Chapter 1, Section 1.1.5.3, of the Carpet Policy Dialogue Compendium Report highlighting these concerns.

“1.1.5.3 TVOC Data and Chemical Speciation

TVOCs [sic] implies the sum total of volatile organic compounds emitted from a test material as measured by a specified analytical test method. TVOC is specifically mentioned throughout the Federal Register notice (55 FR 17404) as the priority datum for consideration by the Carpet Policy Dialogue. Yet, neither the method by which TVOC was to be determined, nor the use of information gathered in the course of obtaining TVOC values was specified. Speciation issues were discussed at the both the Product Testing and Process Engineering Subgroup.

The analytical test method developed by the Product Testing Subgroup produces a TVOC emission factor. The test method can also be used to identify individual VOC chemicals emitted from the test specimen. (See Appendix E).

Some representatives noted that the limited data available for many of the products that would be included in the various testing programs showed that the TVOC levels were low after 24 hours and that reporting speciated data at such low levels would not only produce results which could be subject to misinterpretation, but could also result in disclosure of confidential business information. They questioned the value of committing the costly scientific resources needed to obtain chemical speciation. Some other representatives shared a different opinion on this subject (e.g., Hirzy, 1990).

For the testing program, EPA directed the Plenary and the Testing Subgroup to follow the charge of the Federal Register regarding TVOC for the purpose of testing. A minority report was filed on this subject and is included as Attachment F-2 to the Carpet and Rug Institute Consensus Statement (Appendix F).

The speciation issue was also addressed by the Process Engineering Subgroup. Some members of the Process Engineering Subgroup were of the opinion that the Subgroup could not fully address its charge to identify opportunities to reduce emissions in the absence of information about the nature of the materials used in product manufacturer [sic] that could contribute to VOC emissions. Other Subgroup members contended that such information was proprietary, not readily available, or that available information would not be relevant because of changes in analytical procedures or changes in manufacturing processes. Some Subgroup members expressed concern that without such information, the Subgroup would not be able to fully evaluate the advantages or limitations of various process variables among different manufacturing processes. EPA stated that, consistent with the directives of the Federal Register notice, new studies developing speciated data were not within the scope of the Dialogue but requested that existing speciation data be provided for consideration by the Process Engineering Subgroup.

An account of the deliberative proceedings on the speciated data issue can be found in Chapters 2 and 3. Additional information on this subject is included in the minutes to the meetings of the Carpet Policy Dialogue which are filed in the Carpet Emissions Administrative Record.”

Secondly, I want to introduce the opinions of Dr. Lars Mølhave of Arhus University, Denmark on the proper use and the misuse of TVOC. Lars is credited with providing a scientific basis for TVOC through his human exposure studies in which groups of subjects were exposed to varying concentrations of a mixture of 22 VOCs that was proposed to represent VOC mixtures in buildings. As part of a debate on TVOC recorded in two issues of the Indoor Air BULLETIN (Hal Levin, Editor) in 1996 and 1997, Lars had a lengthy response to the first article “TVOC: Is it Dead?” He concluded with recommendations to practitioners regarding the use and misuse of TVOC. Here I summarize his main points:

1. TVOC does not cover effects other than sensory irritation which occurs at very high concentrations above those typically found in indoor air;

2. If VOCs are important, use more accurate evaluation procedures than TVOC;

3. TVOC can only be used for discomfort issues, for screening purposes, and never for a Yes/No decision;

4. There is no scientific basis for establishing official limit values;

5. TVOC can never be used to provide Yes/No decision regarding acceptability of a building product.

The following is the text of Lars Mølhave’s message to the practitioner transcribed from Indoor Air BULLETIN Vol. 3 No. 8, January 1997.

“Therefore, the essence of my message to the practitioner has been that in doing IAQ evaluations they should do the following:
a) Not only focus on VOC. There are other physical, chemical, and biological factors to consider in relation to IAQ. TVOC does not cover these factors and TVOC is not a measure of general IAQ, but rather of the possible contribution of VOC to IAQ problems.
b) Not only focus on sensory irritation. There are other health and comfort effects to consider in relation to IAQ. TVOC does not cover these effects.
c) If more accurate evaluation procedures are developed in the future, then use them instead of TVOC if you expect VOC to be a major exposure factor.
d) If such methods do not exist, then as a fallback solution, measure TVOC in a standardized way (e.g., according to EU-ECA WG-13).
e) The practitioner may then use TVOC to extract a minimum of health information from the lists of measured compounds. This can only be made in relation to discomfort, for screening purposes, and never for a sharp Yes/No decision. This means that only very small TVOC values are of no concern and only very large values can be classified as unacceptable. In between, the practitioner has to do something else to demonstrate that VOC is part of the problem.
f) My approximately lO-year-old summary and conclusions about TVOC levels (MøIhave, 1986) found in field investigations was already then, when published, described as being based on an incomplete review of publications using measurements which were not standardized. As concluded both by EU-ECA WG13 and by the Nordic group, little additional information has been made available since then, and there is still no scientific basis for setting official limit values. The use of the values 0.2 and 3-5 mg/m3 in this context as recommended definitive guideline values is not advisable.”

Authoritative consensus standard organizations have commented on the use and misuse of TVOC from a practical, methodological perspective. In the authoritative ISO standard on VOC emission testing, “ISO 16000-9 Indoor air — Part 9: Determination of the emission of volatile organic compounds from building products and furnishing — Emission test chamber method”, Section 13 clearly states that TVOC should not be used across products that emit different mixtures of TVOC.

‘Section 13 – The sum of emitted compounds, TVOC, should be regarded only as a factor specific to the product studied and only to be used for comparison of products with similar target VOC profiles.”

ASTM Committee D22 on Air Quality has defined TVOC. This definition contained in “ASTM D1356-05 (2010) Standard Terminology Relating to Sampling and Analysis of Atmospheres” was largely the work of individuals from the U.S. EPA group responsible for developing U.S. air sampling methods for VOCs. The essence of the definition is that TVOC is an approximation and that the measured value is determined by all of the minute the details of the method and by the composition of the air sample with respect to the various chemical groups.

“Discussion – TVOC air concentrations are approximations and are typically determined by summing the areas of all gas chromatographic peaks derived from test methods such as D5466 or D6196. The TVOC air concentration values so derived depend on the type of air sampler; the type of GC detector and how it is calibrated; the collection, retention, and recovery efficiencies of the sorbent trap, canister, or other sampling device; the efficiency of transfer to the gas chromatographic (GC) column; the type and size of the GC column; the GC temperature program and other chromatographic parameters; how the concentration is derived from the peak area (for example, whether single or multiple internal standards are used, as well as the types of reference standards); and the composition of the air sample (for example, the relative abundances of hydrocarbon, halogenated, or oxygenated compounds).”

Based on these facts and authoritative opinions, I find it difficult not to conclude that TVOC is unsuitable as a metric for determining the Pass/Fail acceptability of VOC emissions from building problems. There are severe measurement issues when TVOC is applied across products with different VOC constituents. Such measurements are not even semi-quantitative as accuracy will vary widely depending upon the mixture. At its origin, TVOC served one industry well because its products were actually a very low VOC source relative to other categories of indoor products (representatives of those other industries were not at the table to defend their products). That’s all ancient history; we have moved on to a situation where VOC speciation is routine and substantially more is known about toxicity of individual VOCs. Lars Mølhave, an authoritative scientific expert, didn’t mince words, “It [TVOC] can never be used to provide a sharp Yes/No answer about the acceptability of a product.”

Everyone would like an easy solution, but that’s not a realistic expectation. There is hard work to be done requiring the cooperation of stakeholders and experts to devise a better, yet practical, way to treat the emissions of VOCs for which clear guidance on acceptable exposures is not readily available. The NSF/GEI IAQ standard development activity provides an excellent vehicle to get this work done. It's time to move beyond TVOC.

Here we are not talking about what which scientist said 30 years ago - we are working on improving indoor air quality by promoting products with low VOC emissions into indoor air - for reducing potential risks to human health, such as cancer, allergies and more.
We can of course decide to wait until scientists agreed on individual limit values for each single VOC in indoor air. But this will take decades, if not longer. And such science-based limit values will be different by country, by certification program, even by university.

In Europe we decided to go a pragmatic and precautionary way. On the one hand we are having lists of 150-200 VOC limit values for indoor air quality that were derived from occupational exposure limits (OEL, TWA or MAK), and on the other hand we are restricting overall VOC emissions with the help of a TVOC limit - as a surrogate for the many remaining VOCs not having a limit value. And TVOC then is defined in such a precise manner that no severe measurement problems are observed.
I agree, this is not latest scientific presision, but this an easy to handle way of limiting VOC emissions into indoor air.

LEED is about environmental leadership. In contrast to that ambition, any approach without TVOC limit would be considered in Western Europe as a fall-back to technology of some 20 years ago.

I’ve found it interesting to read these posts and take in the varying opinions on the use of TVOC. I agree with Mr. Oppl’s last post and think it is the most important to consider.
I think the decision to use TVOC depends on several factors, one of them being your overall objective. If you are attempting to reduce overall concentrations of indoor air pollutants; the use of TVOC makes sense. If your goal is to include only measurements meeting certain data quality objectives or metrics based strictly on risk assessments, then TVOC (as well as other methods and measurements) would need to be evaluated to those data quality objectives. We also need to keep in mind that the Europeans have a much larger list of chemicals that they have established limits for. In the absence of such an extensive list of chemicals in the US, then the application of TVOC makes even more sense.
It seems the most significant argument against TVOC is the following: the lack of risk based scientific information to establish limits and the inherent bias in TVOC measurements. Those are understandable concerns however considering that the objective the low emitting interiors section of LEED is to produce exactly that, “low emitting interiors” it would seem that the use of TVOC makes sense.
If the consensus is that a limit of 500 ug/m^3 at 14 days is too low for the purposes of LEED, then selected a higher limit, but based it on emissions data from actual products. The limit used is certainly a topic for discussion, I agree. Often, these decisions require the use of the best available information.
A common argument against any measurement technique or method often has to do with cost or bias. I find that those arguments are valid only when the technique or method can be improved with further work or was hastily developed. I’m not convinced that is the case with TVOC as it has been around for years. In the absence of a significant number of risk based limits for indoor air pollutants, not using TVOC due to its bias is like saying we don’t want to measure PCBs in soil due to the inherent bias that the soil matrix introduces into the measurement. Instead you measure PCBs in soil because that is your goal.
I see people putting a lot of minutia into excluding TVOC from this section of LEED and the irony is that TVOC is already in this section of LEED, but only for some product. Why should one product have to meet a TVOC criteria but another product not? I keep coming back to the same points which I made earlier: 1) don’t use TVOC as a criteria by itself and 2) the current criteria lists used for indoor emissions in the US cover such a small number of chemicals found in indoor air. Given the extensive work required to develop additional list and risk based limits, TVOC is a practical approach to this issue.

What can Reinhard Oppl be talking about in his comment about 30 years ago? In about that time frame occupational levels with some modification factor, either 1/10 or 1/40, were recommended and widely used as the basis for indoor air assessments in the U.S. and to some extent in Canada . Now he claims that Europe is taking a cautious approach by using occupational limits as the basis for "150-200 VOC limit values." This is hardly precautionary since the reliance on occupational limits has been dropped due to the lack of a scientific basis for most of them and their lack of relevance to exposures in indoor non-industrial contexts. Certainly occupational limits based on industrial exposures in healthy workforce populations are not going to be an effective basis for non-occupational exposures to protect children, the elderly, the infirm, and even healthy adults exposed for 168 hours per week rather than 40, and exposed to a complex mixture, not to single compounds, the basis for occupational limits.

Oppl seems to be criticizing Hodgson for references to Molhave's work leading to the values often recommended for TVOC exposures. But not only did Molhave base his recommendations on a mixture of a specific concentration of each of 22 substances, he has also, as Hodgson pointed out, suggested that TVOC cannot be used as an indicator of health effects. This was not 30 years ago but within the past decade.

Even if all the problems identified by Hodgson with measurement of TVOC were resolved, it is clear that using a TVOC metric with a concentration limit of 200 to 500 micrograms per cubic meter or an emission limit of those values per square meter per hour can easily result in very high TVOC values. The TVOC mixture may be relatively harmless at far higher values or relatively dangerous at far lower values. There is simply no assurance either way, and relying on TVOC creates a false sense of safety if limit values are not exceeded. Then there is the problem that the emissions of multiple products, each meeting the maximum values could easily result in extremely high concentrations, yet each product could pass the emission test based on its meeting the TVOC limit.

Brian Englert's post unwittingly argues against the use of TVOC while purporting to argue in favor of it. He argues for risk-based science but ignores it in his example citing PCBs in soil. He uses PCBs in soil to try to make a point that is not entirely clear. But PCBs are, in a sense, like TVOC. Risk assessments stopped looking at total PCBs many years ago in recognition of the fact that varioius PCBs have highly variable potential health effects. PCBs are polyhalogenated aromatic hydrocarbons that consist of up to 10 chlorine atoms attached to a biphenyl group. About 130 of the 209 theoretical PCB congeners were manufactured between 1929 and 1977 as mixtures and were sold as a function of chlorine content. Analysis is done by specific congener and risk assessments are weighted based on the composition of the mixture, not on the total PCB concentration. the weighting is done based on the relative toxicity of each congener and its presence in the measured mixture. Following that approach simply argues against TVOC, not in favor of it.

His implicit claim is that TVOC is not susceptible to improvement because it "has been around for years." PCBs were around for many years before the analysis of the distinct congeners became a routine part of the analysis. This was because it was found that there was considerable variation in the toxicity of each of the congeners and that a risk-based assessment required distinguishing them from each other for a valid, health-based assessment.

TVOC was originally used primarily for "easy" measurement of solvents in industrial settings where only one solvent was known to be present and where a TVOC measurement could be expected to be strongly dominated by that solvent. Sampling and analysis was simple and quick. But as more compounds became concerns, compound-specific analysis became routine. That's exactly where all the 150-200 occupational limits Reinhard writes about came from.

We know what the most common compound are in indoor air, and with a collaborative effort, we could easily assemble a list of the most commonly emitted VOCs from the most commonly used products. As long as there is reliance on TVOC, there will not be sufficient motivation to understand the details that would inform such an effort. Only by acknowledging the inadequacy of TVOC can the stakeholders muster the cooperation from all concerned parties to undertake such an endeavor. With such a list, efforts can begin to establish relevant indoor guideline values for use in evaluating the results of emissions testing.

Just a short correction:
The 150-200 limit values are not occupational exposure limit values, these are emissions into indoor air limit values, see also page 10 of this study: http://www.epa.gov/iaq/pdfs/hal_levin_paper.pdf, and the new discussion thread on Indoor air emissions limit values, started on Jan 03, 2011.

Disclosure: I am the Regulatory Affairs Director for PROSOCO Incorporated. Additional information is posted elsewhere in this forum.

I appreciate the LEEDUser Forum as an avenue for constructive comment and debate on various aspects of LEED ratings system development. While brevity is important, the technical and policy issues we face on future handling of coatings and sealants are complicated – a simple distillation would leave us with little more than talking points from the various parties involved to date. These comments are focused on TVOC. I will address additional policy questions through creation of a new thread.

The USEPA definition of an architectural coating includes any material applied or impregnated into an architectural substrate for functional or decorative purposes. VOC regulatory work is a specialized, niche discipline as each and every product must be properly categorized with accurate formulary VOC determination. The AIM VOC legacy system is the primary driver for our industry; I request that readers bear this in mind during discussions on the future of LEED as it applies to these products.

The coatings industry is a relative newcomer to the emissions testing system; our limited participation stimulated by inclusion of credits within LEED for Schools and through CHPS. I say limited based on the fact that only several hundred commercially available coatings have been tested out of the tens of thousands in the marketplace. The vast majority of tested products are basic mass market flat and non-flat wall paints – relatively few specialty coatings have been tested.

The paints and coatings industry is broad and diverse. Some statistics for the reader’s benefit:

Based on the 2007 Economic Census and 2007 Nonemployer Statistics, there were 1,370 paint manufacturing establishments in the U.S. This only counts the primary NAICS classification for general coatings production and does not capture all of the specialty product formulators.

As of today, a total of 19 paints and coatings manufacturers are listed as having achieved third-party certification under the SCS Indoor Advantage Gold or GreenGuard Children and Schools programs.

These statistics are telling. Precedent setting policy discussion must take into account the other 1,351 U.S. manufacturers who currently have minimal engagement with this policy discussion and associated third-party certifications. To be fair, an unknown number of manufacturers are having products tested without utilizing the services of third-party certifiers. However, said manufacturers have not been part of any system utilizing a TVOC limit – this being a feature of one third-party certification system.

As a latecomer to a legacy emissions testing system that has existed in one form or another since the early 1990’s, the coatings industry has been absent from stakeholder discussions until late 2009. My understanding is that the TVOC concept dates back to a Carpet Policy Dialogue from the peak era of sick building syndrome concerns in the mid-1980s. The numerical criterion was developed during study on occupant irritancy thresholds that approximated indoor exposures at that point in time. In many ways, it reflects a chemical species mixture that has little relation to modern coatings formulary chemistry.

The coatings industry has been subject to multiple rulemaking cycles progressively limiting the VOC content of products in prescriptive and legally enforceable standards – the latter factor being unique to coatings and sealants among construction products. Coatings are generally simple mixtures of materials combined at ambient temperature and pressure with no reaction chemistry involved. Simply stated, manufacturers know what chemicals are in their products because lack of knowledge can lead to expensive and potentially fiscally fatal enforcement. More importantly, market transformation brought about by the creation of LEED has created a current expectation that significant new building odors are simply intolerable.

I believe Al Hodgson’s and Hal Levin’s comments adequately reflect my position on the topic of TVOC: TVOC can be used as an indicator for additional study and chemical compound speciation and toxicity thresholds; however, it is inadequate as a pass/fail metric. In my opinion, within the context of the coatings and sealants industry, use of a TVOC measurement for any other purpose than as an indicator can be misleading to downstream users.

I preface the following discussion with a clear statement that PROSOCO’s tested products have been demonstrated to pass a hard TVOC metric of 500 ug/m3. Stringent application of this TVOC metric would actually provide my employer with a short term market advantage; potentially over other coatings and flooring materials with which we compete.

Use of TVOC as a pass/fail metric based on the precautionary principle does sound comforting. However, the history and science behind the number are relevant as is the process of getting it right. There are significant differences between the CDPH and various EU country approaches and numeric limits – this includes both the product testing period and the TVOC limit. In my opinion, even if consensus were achieved on mandatory application of TVOC, there is no fundamental consensus on where the limit should be set. Herein lays the flaw of utilization of TVOC criteria as a pass/fail metric: it’s easy to lose sight of the big picture when applying black and white thinking.

Let’s consider some potential real world scenarios. Suppose a coating has TVOC emissions of 490 ug/m3 of perchloroethylene because of use of this chemical as a VOC exempt carrier solvent. Is this coating better than a viscous high build coating with a slower emission rate and over 500 ug/m3 TVOC comprised of ethyl alcohol? Is it better than a floor covering incorporating pine resin measured at over 500 ug/m3 TVOC at 14 days? What if the floor covering passes at 28 days? What if a problem is recognized during preoccupancy screening and can be corrected by a modification in flush out procedures?

Yes, these are rhetorical questions easily dismissed. However, as an employee of a company that has contributed to the restoration and conservation of over 30 state capitol buildings and the U.S. Capitol, I am concerned about a fundamental question: will the specified products actually contribute to the longevity of the substrate and decrease life-cycle chemical and materials use during the life of the building?

Indeed, a sustainable building system cannot be considered sustainable if it has the potential to harm building occupants. However, unless we dive deeper into the details of emissions and chemical exposure risk, we run the risk of creating a system skewed to meeting one primary metric at the cost of actually constructing buildings that will support their occupants without significant downstream impacts to the environment. If TVOC is that metric, manufacturers will respond within a narrow set of product design constraints. Perhaps the end result will contribute to a durable system. In my opinion, it is just as likely that many novel and innovative approaches will be considered and abandoned simply because they won’t pass this one narrow criterion. I personally prefer a balanced approach that allows innovation and competition in the market place.

I agree with other commenter’s assessment that the CDPH CREL list does not include enough chemicals. The list should be expanded in a scientifically valid manner. As Hal Levin suggests in his December 31 post, it would make sense to focus on the VOC species known to exist in new buildings. However, for products with known formulary components or groups of similar products it makes no sense to test for everything simply to prove a negative.

Emissions testing represents a significant overhead cost. Truly innovative materials enter the market with no specification base or sales volume. More often than not, niche product manufacturers adjust formulations once they receive feedback on real world use. Reputable manufacturers would retest regardless of whether they are first or third party certified.

Some commenters propose that LEED is a leadership program and that is somehow incomplete without a precautionary principle application of TVOC to all interior construction materials. The concept of TVOC has indeed been in existence for over twenty years for a select set of interior products. For others, it has existed as a voluntary presumption of innocence as a substitute for pre-occupancy indoor air screening – this primarily in the purview of one third-party certification system. To take a voluntary limit based on irritancy thresholds for chemical species from twenty years ago and set it as a mandatory pass/fail standard involves a certain leap of faith that I’m not convinced is supported by the facts.

Some commenters argue that economics should not play any part in testing products for IEQ performance. I’ve already shared this manufacturer’s perspective on the market economics of specialty coatings products. Testing and retesting is not inexpensive. Coatings formulations will change based on field experience thus triggering retests. Technology stagnates when the overhead costs preclude adjusting formulations to optimize performance. Formulary adjustment would also entail risk that emissions rate curves change and make a product no longer conformant to a numeric TVOC limit. That’s OK as long as the TVOC number is truly relevant, but we’ve seen credible comments on this from credible technical experts on the subject that indicate this is not necessarily the case. In my opinion, a TVOC pass/fail limit will artificially constrain choice and diversity of available specialty products.

I have read and, to a certain extent, agree with the assessment that some coatings products harbor a wide variety of VOCs. This is certainly true for mineral spirits and petroleum fraction mixtures such as bituminous materials. However, these complex mixtures are not widely used for interior coatings formulations. I propose we simplify the argument by adding specific language excluding the use of coatings labeled or marketed for exterior use in building interiors. Coatings labeled for interior or dual use can then be judged on their overall health and performance profiles.

I believe it fair to have some expectations on which formulary components should not be incorporated into sustainable building interior coatings products. A prescriptive approach can reduce uncertainty on the part of specifiers and manufacturers. As a starting point, I recommend adoption of the exclusion of toxic VOC exempt solvents as specified in the Bay Area AQMD AIM VOC regulation. Perchloroethylene (dry cleaning solvent) and methylene chloride simply have no legitimate place in a sustainable building interior.

A more extensive list of non-preferred chemicals should be generated through a stakeholder process and should be based on chemical species that actually appear in modern formulations.

Thanks Dwayne. Please post a link to the Bay Area AQMD AIM VOC regulation toxic VOC exempt solvents language to we can take a look.

Tom: I included a link and the language in my comment regarding general recommendations for paints and coatings credit language. The regulatory language is not suitable for use as is. It's one of those times where an agency chose to pare down the long list of exempts without actually calling out the names of specific toxic exempts. I live in VOC regulatory world and the language is often difficult to parse.

The BAAQMD approach is to list allowable exempts that are relevant to coatings. For the sake of consistency with other California rules, I think it makes sense for the LEED Credit language to specifically exclude the toxic exempt solvents methylene chloride and perchloroethylene. There are other toxic exempts, but they are not relevant to coatings and most have been eliminated through general bans such as the one on ozone depleting substances.

If the IEQ TAG decides this is even a valid approach, we can have further consultation on specific credit language.