You are correct, the GBC has information about the lesser used EPA Compendium of Methods for the Determination of Air Pollutants in Indoor Air (a.k.a. the “IP” compendium), of which IP Methods IA (canisters) and IB (sorbent tubes) are relevant to LEED VOC testing. A much more widely used compendium is the EPA Compendium of Methods for the Determination of Toxic Organic Compounds in
Ambient Air (a.k.a. the “TO” compendium), of which TO-15 (canisters) and TO-17 (sorbent tubes) are relevant. Most likely because the IP versions are nearly identical to the TO versions, and the TO methods are much more widely offered by commercial laboratories, many LEED practitioners have used the TO series.

As for your question of who exactly makes a final decision on the acceptability of test results, that is a great question to which I am unsure of the answer. I suspect it is up to the LEED reviewer, and that in most cases, that person is less familiar with the technical differences between different analytical methods/techniques–thus that is why you see many projects accepted with using alternate methods such as OSHA07, handheld PIDs, etc.

In our laboratory’s opinion, the analytical technique that will capture the VOCs which are most relevant to LEED projects (e.g. emissions from carpets, adhesives, building materials, etc.) involves solid sorbent tubes which are analyzed via thermal desorption GC/MS. A few years ago, we conducted some side by side testing using multiple techniques (canisters, thermal desorption tubes of various types) in a facility pursuing LEED accreditation. Active TO-17 samples ended up capturing VOCs that were missed in other sampling approaches, such as texanol (from latex paints) and various glycol ethers. On a side note, another advantage of using TO-17 for the TVOC evaluation is that 4-PCH may be determined from the same sample.

The bottom line is, we still see LEED practitioners performing a variety of techniques to meet the TVOC measurement criteria in EQ 3.2. Our laboratory can perform the various analytical methods and advise you on the pros and cons of each. Best of luck!

1. Who makes the final decisions regarding the acceptability of test results? Is that up the the LEED reviewer who looks at the overall certification documentation submitted by the project manager?

2. Are other methods acceptable besides TO-1A and 1B, and if so, what is the justification or reference that allows it?

3. I am considering purchasing a handheld PID that, like your article describes, has a resolution down to the PPB level. The EPA compendium describes PID for use as a screening tool — does this suggest that it might be acceptable?

Thanks!
Louie

Great question! To the best of our knowledge, there is no health basis for the 500 ug/m3 TVOC limit–it is likely more based on typical concentrations seen in the indoor environment. The 500 ug/m3 value can be traced back to a State of Washingron Depamnent of General Administration Indoor Air Quality specification from a 1989 document. Obviously, the largest flaw in the 500 ug/m3 limit is that it does not give any limits of any individual VOCs, so a building with 450 ug/m3 of benzene (comprising the TVOC) would technically pass the criteria.

Thanks

E

For passive diffusion samplers, sampling rates are often determined experimentally for various compounds of interest. So, knowing the sampling duration and using the sampling rate you can assume a certain volume of air sampled. Many sampling rates have been established and published by the manufacturer for sampling media such as the radiello (distributed by Sigma Aldrich), SKC Ultra, etc. Also, the MDHS 80 method has many sampling rates published for Perkin Elmer tubes (including Tenax).

The conversion from ug/m3 to ppbV (or ppmV) involves the molecular weight of the chemical species. Therefore, for a generic term such as Total Volatile Organic Compounds (TVOC), you cannot accurately convert the units. You could make some assumption as to an average molecular weight, or use the molecular weight of a common midrange VOC such as toluene, but again, this would just be an estimation. You can go to our Air Testing FAQ page for more information on the conversion: http://www.caslab.com/Air-Testing/FAQ.php

As for reporting limits (“detection limits”), for the sorbent tube methods (EPA TO-17, IP-1B, and NIOSH 2549), a reporting limit is given in total mass/tube. Concentration unit reporting limits will depend on the volume of air that is pulled through the tube. For canister reporting limits, these will take into consideration the volume of air analyzed from the canister and whether or not the laboratory pressurizes samples upon receipt. However, overall, the reporting limits in canisters tend to be more “fixed” than reporting limits using sorbent tubes since they are independent of the total volume collected.

All the items you ask about are perfect examples of the data quality objectives that must be discussed with your analytical laboratory PRIOR to sampling.