Maximum allowable concentration of formaldehyde and other VOCs

Youyou,

After having read some of my previous posts you probably know my opinions about the requirements in LEED EQ Credit 3.2 (2009) and EQ Credit 4 (v.4). Previous versions of LEED had an allowable formaldehyde level of 50 parts per billion (ppb) which is the level that had been used as an IAQ guideline for decades. The occupational exposure limits for formaldehyde include the OSHA 8-Hr Time Weighted Average (TWA) Permissible Exposure Limit (PEL) of 750 ppb, ACGIH Ceiling (not to be exceeded anytime during a shift) TLV of 300 ppb, and the NIOSH 8-Hr TWA REL of 16 ppb. The ACGIH (American Conference of Governmental Industrial Hygienists) has been setting exposure levels for hazardous substances since 1946 (reviewed annually and updated as needed).

The 27 ppb level came from the California Air Resources Board regarding home formaldehyde levels and was adopted as an Office of Environmental Health Hazard Assessment (OEHHA) 8-Hr TWA interim guideline in the early to mid-2000s. The OEHHA was officially formed in 1991 along with CalEPA though it had existed in other forms prior to that. One of the driving forces was Proposition 65 which passed in the mid1980s which requires warnings on products with hazardous materials/chemicals in them that have been determined (by California) to cause a greater than 1 in 100,000 risk of cancer or have other recognized health hazards. Much of OEHHA’s focus has been from an EPA perspective with the intent of preventing things like outdoor air pollution (smog), toxic exposures to neighborhoods, soil and water pollution, etc. It uses health based risk assessments which, in my opinion, involve a lot of voodoo and don’t take reality (i.e., background or normal levels) into account.

The current 8-Hour and Chronic (for residential type exposures) OEHHA reference exposure levels (RELs) for formaldehyde are 9 and 9 micrograms per cubic meter (ug/M3), respectively, which converts to 7.3 ppb (watch your units). This level is so low it can commonly be found as background in outdoor air. Researchers (Moser et al in 2005) measure formaldehyde in human breath and found a median level of 4.3 ppb and a level of up to 6.3 ppb in 25% or more of those tested. Pretty close to the 7.3 ppb OEHHA level I’d say (don’t breath on your formaldehyde sampler). It is a metabolite of our bodies. This is what I mean by voodoo.

One last comment on the formaldehyde question regards the methods proposed in LEED. The EPA Compendium indoor air methods were created in 1990, have not been updated since, and are not typically used by IAQ professionals. LEED doesn’t even mention the method currently most used which is the National Institute of Occupational Safety and Health (NIOSH) method 2016.

Regarding the LEED v.4 Target Chemical List, the title of the referenced Table 4-1 is “Standard Method for the Testing and Evaluation of Volatile Organic Chemical Emissions from Indoor Sources Using Environmental Chambers Version 1.1”. As you can see, this is not a table of indoor air quality values for chemicals to which an occupant should or should not be exposed but rather the maximum amount of chemical a product placed in a test chamber should give off. Yet it is being used to evaluate indoor air quality before occupancy as stated in the LEED v.4 intent statement (i.e., “To establish better quality indoor air in the building after construction and during occupancy”). The Table 4-1 levels have little to do with occupant health or future indoor air quality. At best it is a quality control measurement to evaluate the effectiveness of using low emitting materials. This lack of accomplishing the stated intent of the Credit applies not only to the Target Chemical list but also to the other parameters in the air testing credit, especially the total volatile organic compound (TVOC) level of 500 ug/M3 which, in my opinion and that of many of my peers, is of little value in assuring good IAQ and has little to no scientific basis. Also, as I have stated previously, the other aspect of LEED IAQ Credits, flush out, is a big waste of time, energy, and money for little to no value (of course - my opinion).

As far as the where the Table 4-1 levels come from they were arbitrarily (my opinion) chosen to be ½ the OEHHA Chronic (long term mostly applicable to residential exposures) Reference Exposure Levels (RELs) found at http://www.oehha.ca.gov/air/allrels.html. A commonly applied rule in industrial hygiene is that you use ½ the OSHA PEL or other occupational exposure limit as an action level which requires continuing monitoring, employee training, implementation of controls measures, etc. Maybe that is where the ½ came from. Regarding why formaldehyde is exempted from this halving, I would assume that since the current Chronic REL for formaldehyde (7.3 ppb) is basically background that halving it would be impractical. Besides, most current air testing methods don’t detect formaldehyde at that low a level.

It is really past time for the USGBC and other Green building system, codes, and standards to stop guessing at what is appropriate for good IAQ and talk to the experts (i.e., certified industrial hygienists (CIH) and other IAQ professionals) in order to accomplish the stated intent of the IAQ testing and other IAQ credits and prerequisites. I did notice that the last call for volunteers for the USGBC IEQ Technical Advisory Group specifically requested CIHs to apply. This is encouraging. I and some of my CIH colleagues have applied. We’ll see what the future holds.