Accredited Environmental Technologies, Inc.        









Inspirational Quotes

We are judged by what we finish, not by what we start.

A man's reputation is the opinion people have of them; His character is what he really is.    
Jack Miner


  • Shorter is Better
  • Targeted is Better

Expect 3 Separate Newsletters for June

  • Carpeting
  • HVAC
  • Construction Defects


What's That Smell? Formaldehyde

Adhesive Resin in Pressed Wood Products


is a colorless, strong-smelling gas with a pickle-like odor which is off-gassed from plywood and particle board.  It is  commonly used to make furniture, cabinets, wall paneling, countertops, shelving and sub-flooring. IAQ concerns from formaldehyde occur primarily in new construction. Off-gassing, greatest when the product is new, decreases over time and is accelerated by warm temperatures and high humidity.

Health Effects/Standards

     Based on its pungent odor, formaldehyde can be detected at very low levels (odor threshold reported as low as 0.03 ppm). It can cause burning/watery eyes and upper respiratory tract irritation at levels as low as 0.1 ppm. Other common symptoms include coughing, headaches, dizziness and nausea. It is also a sensitizing agent that can cause allergic reactions and asthma-like symptoms after repeat exposures. It is also listed as a probable human carcinogen (increased nasal cancers in mice and rats).

OSHA Standard



Action Limit






.002-.006 ppm

     Liquid Formalin

is a mixture of formaldehyde, alcohol and water, used as a preservative in the health care industry. Formalin is also used in the treatment of textiles (such as permanent press and dyes including draperies) and the production of resins, glues and adhesives. In addition to the exposure by inhalation, liquid formalin can also be absorbed through the skin.

     AET Project Profiles:

Formaldehyde is routinely evaluated by AET during IAQ investigations involving new construction. Formaldehyde is also a basic component of LEED Baseline IAQ evaluations for new construction and major renovations with a maximum level of 0.05 ppm. IH exposure evaluations are also performed involving liquid formalin in hospitals, medical laboratories, school biology laboratories and mortuaries.

Case Studies:

     Since the early 1980's, formaldehyde levels in homes and commercial properties have decreased due to the significant reduction (80-90%) of formaldehyde emissions from pressed wood products. Low emission phenol-formaldehyde has replaced Urea formaldehyde. Urea formaldehyde foam insulation (UFFI) use has dropped significantly since the CPSC attempted to ban it in 1982.

     Enter Katrina 2006

... The government purchased over 120,000 mobile homes and trailers to house Gulf Coast victims. As IAQ complaints arose, these trailers were identified as "toxic tin cans" by the press. In July 2008, the CDC recommended relocation of these residents due to confirmed elevated formaldehyde levels and associated occupant symptoms. A CDC study of 519 of these trailers found formaldehyde levels ranging from 0.003 to 0.590 ppm (mean 0.077 ppm). A significant quantity of the trailers exceeded 0.1 ppm, a level where symptoms are known to occur.


Purchase low-emitting products; Review manufacturer emission data during product selection prior to purchase.
  • Allow products to off-gas before bringing them into your home or commercial building. Leave the product unsealed in the warehouse.
  • Allow sufficient flush-out time (48-72 hours) after installation of pressed wood products prior to occupancy. Increased ventilation to the occupied space is recommended by opening dampers, windows, doors, etc.
  • Seal pressed wood products with varnish or latex based paints. Vinyl coverings such as wallpaper and floor coverings will also reduce gas emissions.

How Clean is Clean? HVAC

     Even a new HVAC unit/ductwork will contain surface dust. Once operational, surface dust levels within HVAC systems will increase as dust (including mold spores) are drawn into the fresh air intake. AET uses a 3-tiered approach to evaluate HVAC cleanliness.

  1. Visual inspection
  2. NADCA vacuum test method (
  3. Mold or specific contaminant testing by swab, wipe or tape lift sampling

Case History - HVAC Ductwork Evaluation:

A significant sprinkler discharge flooded a 4-story hotel during construction. Extensive mold growth resulted requiring the removal of all interior drywall walls and ceilings. AET was tasked to evaluate the impact of mold growth and the recently completed mold remediation on the hotel's HVAC system. Visual inspection and surface dust sampling confirmed only a small section of supply duct required cleaning or replacement;

a significant time and cost savings to the client.

HVAC Malfunction

     NIOSH Studies indicate >50% of IAQ complaints result from HVAC problems in the workplace. At AET, every IAQ investigation starts with the location of the outside air intakes and work backwards through the HVAC system to where the conditioned air enters the workspace. Critical investigative data is obtained concerning the HVAC system and its components as detailed below:

  • Contaminant entry associated with fresh intake location.
  • Operational parameters including damper settings
  • Type, efficiency, integrity of filters
  • Condition and cleanliness of coils
  • Determination if the ductwork is lined and dust loading near the cooling coil.

Case History - Moisture impacted fiberglass (downstream from cooling coil):  Occupants at a commercial building reported a foul, musty odor. Inspection of the HVAC units found the unit controls were malfunctioning.  Return and outside air dampers were frozen inplace and non-operational. Further, the unit supplied air discharge temperature was 49̊ F (should be no less than 55̊ F).

Problem Identified: 

Malfunction of the HVAC system resulted in significant water impact to the interior-lined, fiberglass insulation as a result of condensation from low dicharge temperature. The insulation exhibited the odor due to bacteria growth on the wet fiberglass.


Due to the age of the HVAC unit, the unit was replaced. In addition, the internal insulated supply ductwork extending 25' downstream from the coil was also replaced.

Foreclosures, Sheriff Sales, Quick Sales... Don't be a Dope!

     New home buyers, investors... Beware! When you go house hunting you should be looking for more than for sale signs. Other signs you should be alert to are indications the house you are considering may have been a former marijuana grow house.

     Extensive mold growth in these homes have resulted in 10's of thousands of dollars in mold remediation to cover the cost of extensive interior demolition of walls, ceilings and furnishings. Mold growth is the result of high humidity conditions required to grow the plants. Plants grow best when temperatures exceed 80̊ F and with 80% or higher relative humidity. About ½ of a liter of water per day, per plant, is put into the air to promote plant growth.

Recognition Problem:

Many properties are bought sight unseen (or as is). Gro op may have been in the past and renovations completed. Further, cosmetic alterations (such as painting) may have been used to hide the real danger before being put up for sale.


  1. Ask your real estate sales person about the property history.
  2. Obtain/review the seller property disclosure form.
  3. Utilize a certified home inspector. Extensive mold growth may also have caused structural damage adding to your cost and a structural engineer may also be needed.

Top Ten Signs that a home may have been used as a Grow House (According to the Toronto Police)

Mold in corners where walls and ceilings meet.
  • Unusual number of roof vents or signs of roof vents.
  • Fresh paint on window frames to cover damage caused by high humidity levels.
  • Painted concrete floors in the basement with circular marks where pots once stood.
  • Evidence of tampering with the electrical meter.
  • Unusual or modified wiring on the exterior of the house.
  • Brownish stains on the underside of beams or arches.
  • Concrete masonry patches or alterations on the inside of the garage.
  • Patterns of screw holes on the walls.
  • Denting on front doors (from police ramming the door). This one sounds like it's from David Letterman.

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