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  • Shorter is Better
  • Targeted is Better

Expect 3 Separate Newsletters for June

  • Carpeting
  • HVAC
  • Construction Defects

What's That Smell? Total Volatile Organic Compounds (TVOCs)

     TVOCs are a complex mixture of potentially hundreds of low level VOCs encompassing the IAQ of office buildings, health care facilities, schools, etc.  TVOCs are emitted from multiple indoor emission sources such as building materials, operations, processes, maintenance, custodial and the building occupants themselves (see partial listing).

  - fabrics           - comsetics          - paints          - copiers
  - plastics          - soaps               - cleaners       - printers
  - floor wax        - perfumes           - glues           - combustion sources
  - carpet            - disinfectants      - varnish         - cigarette smoke

     TVOCs are emitted in the ppb range and have little or no odor when mixed/diluted by the building HVAC system. However, each has a detectable odor at its source. TVOCs encompass a broad spectrum of organic compounds including aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated solvents, etc.

Health Effects:

Health concerns associated with VOCs center on the additive/synergistic effects of the sum total of the VOCs present. Some are also suspected human carcinogens. Reported symptoms of exposure include fatigue, headaches, drowsiness, skin/eye irritation (especially in hypersensitive individuals).

Concentration Range

Exposure Range

Health Effects


Comfort Range

No irritation or discomfort

0.2 - 3.0 mg/m3

Multifactorial Exposure Range

Irritation or discomfort possible if other exposures interact

3.0 to 25.0 mg/m3

Discomfort Range

Exposure effects and probable headache if other exposures interact

>25.0 mg/m3

Toxic Range

Additional neurotoxic effects other than headache may occur.

AET Evaluation/Standards

: AET utilizes direct reading instrumentation (such as a ppb RAE) to provide real-time readouts of TVOCs. Instrumentation is also utilized to identify specific VOC emission sources. Where individual components of the TVOC mixture must be identified, AET utilizes integrated sampling and GCMS laboratory analysis. TVOC sampling is an important component of AET's odor investigations and LEED Baseline IAQ Evaluations.








.1 TLV for   individual VOCs




Implement source controls such as keeping lids on containers, minimizing the amount of chemicals used, and use of dispenser bottles rather than large containers.
  • Storing paints, cleaners and solvents in areas with separate exhaust and not in an HVAC mechanical room.
  • Increasing outside air levels to dilute concentrations in the occupied space.
  • Installing local exhaust ventilation at specific emission sources such as copiers, printers, laboratories, or photographic darkrooms.

Construction Defects - Brick Veneer

     Brick is porous; it acts like a sponge and absorbs water from rain and exterior sprinklers. When the sun heats up the brick (temperatures may reach 120̊ F), water vapor is created which is driven inwards towards the wall assembly.

Design Requirements:

An airspace (at least 1 inch wide) must be installed behind the brick.
  • The airspace must be free of mortar droppings and vented at the top and bottom to vent out the water vapor.
  • A proper vapor barrier should be installed against the exterior sheathing to act as both a vapor barrier and drainage plane.
  • Water as it condenses against the vapor barrier must be directed by flashing to weep holes to drain any water behind the brick.

Case History - Residential Mold: 

AET is currently working at a residence where the brick was found to touch the house wrap applied to the exterior sheathing (OSB Panel). Mortar droppings also contacted the wrap.  The wrap is not a drainage plane and condensed water easily penetrated through the OSB.

ResultThe OSB is almost completely covered with black mold. The homeowners have moved out due to respiratory concerns. The mold has been identified as basidiospores and petriella.  Both are associated with wood that has been persistently wet.  Slightly elevated endotoxin levels have also been confirmed (i.e. bacteria growth from moisture impacted fiberglass in the wall cavity).


The homeowner plans to remove the brick veneer to access the mold contaminated OSB. The OSB will be removed as well as the fiberglass insulation within the wall cavity. 

Vermiculite:  Asbestos Issues

     Vermiculite is a naturally-occurring mineral which is usually light-brown or gold in color after processing. It is light-weight, fire-resistant, absorbent and odorless. It has hundreds of agricultural, horticultural, construction and industrial uses including as loose fill insulation, potting soil mixes and packing material. Vermiculite in its pure form does not contain asbestos and is a naturally occurng mineral. However, natural asbestos deposits have been identified where vermiculite is mined.

Libby Montana Mine (update):

     Prior to its close in 1990, much of the world's supply of vermiculite came from a mine in Libby, Montana. This mine had a natural deposit of asbestos which resulted in the vermiculite being contaminated with tremolite asbestos. Since 1999, the EPA has spent a reported $200 million dollars cleaning the asbestos contaminated vermiculite associated with the mine, in homes, in businesses and even the outdoor surrounding grounds of Libby.   The Obama administration in June pledged an additional $130 million dollars for cleanup and medical assitance.  Federal prosecuters have stated that over 200 deaths and 100 illnesses have resulted from asbestos exposures in Libby. 

 Attic Insulation:

     Probably the most hazardous use of vermiculite is as an attic insulation. Many homes including some inspected by AET have vermiculite poured into the voids between the attics floor joists for insulation. These joists may be open or covered by the attic floor. Vermiculite attic insulation is easily disturbed and dust levels in the attic can be significant. Attics are also used for storage and stored items are cause for access/retrieval and these items can easily become contaminated.

What to do? Know your attic space and the type of attic insulation used. If you suspect vermiculite, AET recommends:

  • Do not disturb the insulation; keep attic doors closed/sealed.
  • Limit the number of trips and the amount of time spent in the attic.
  • Do not use the attic for storage.
  • Keep children out of the attic.
  • Inspect ceiling below the attic for cracks or openings including around light fixtures, ceiling fans which could allow vermiculite dust to enter occupied space.
  • Test attic insulation prior to renovations or sale of the property to determine asbestos content. PLM analysis is sufficient; However, TEM analysis is recommended.  The cost for TEM analysis is approximately $250.00 per sample.


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