ppb. Some homes had formaldehyde
concentrations of several hundred ppb in
closets or pantries. In nearby San Jose
and surrounding communities, formaldehyde concentration in homes was typically between 30 and 80 ppb.
What was causing the increased
formaldehyde in Los Altos homes? One
possible explanation was that Los Altos
has more energy-efficient green homes
with airtight design results in low outdoor ventilation—and, therefore, higher
indoor formaldehyde concentrations.
Eventually, Kincaid learned that Los Altos
was one of the first cities to require new
homes to be rated by a green certification
program called GreenPoint Rated. This
program, managed by a Berkeley-based
private organization called Built It Green,
is analogous to the U.S. Green Building
Council’s LEED for Homes program.
All Los Altos homes permitted after
Jan. 1, 2008, were GreenPoint Rated.
Neighboring cities adopted similar requirements. Of the new single-family
homes that Kincaid tested in 2009, Los
Altos homes were all GreenPoint Rated;
most homes in other cities were not.
The primary focus of GreenPoint
Rated is energy conservation. According
to Build It Green, GreenPoint Rated
homes are typically 15 percent more energy efficient than conventional homes
built to current building codes. Well-insulated and sealed, GreenPoint Rated
homes allow minimal infiltration of outside air. Unless windows are open, ventilation rates are very low.
The GreenPoint Rated program also
focuses on resource conservation and
encourages the use of engineered wood
to reduce consumption of virgin timber.
Unfortunately, engineered wood products are often manufactured with
formaldehyde resins that emit considerable formaldehyde into living spaces.
Extensive use of engineered wood in a
home with poor ventilation is a recipe
for high formaldehyde concentrations.
new homes, residents have experienced
health effects consistent with formaldehyde exposure.
Initially, the residents suspected
tainted drywall from China. But measurements indicated 50–80 ppb formaldehyde throughout the homes, with higher
concentrations inside the wall cavities.
(All of these measurements were made
with a real-time formaldehyde analyzer,
which has positive and negative chemical interferents. The higher concentrations of formaldehyde in the wall only
suggest that the wall materials—e.g.,
fiberglass insulation, gypsum wall
board—are significant emitters of
concentrations in homes tested were
consistent with formaldehyde in new
homes across the country. Data shows
those concentrations were high enough
to cause illness. The sources of formaldehyde in those homes is not clear.
Southern California Homes
Through much of 2009, Kincaid focused
on the greater San Jose area and the effects of green building ordinances on
formaldehyde concentrations in homes.
Then, in October, she was asked to measure formaldehyde in a 2007 development
in Indio, Calif. Since moving into these
In October 2009, the Consumer Product
Safety Commission (CPSC) report on
Chinese drywall brought further attention to the issue of formaldehyde in new
homes. Concentrations of formaldehyde
in Florida homes ranged from 79 ppb to
130 ppb when air conditioning was off.
Concentrations of formaldehyde in
Louisiana homes were higher (40–400
ppb) when air conditioning was off. The
CPSC report indicated that formaldehyde
The formaldehyde equation has two
parts: first, emission of formaldehyde
from sources such as composite wood
products; and, second, removal by ventilation. Insuring that homes are adequately ventilated helps keep indoor
formaldehyde concentrations from accumulating to high concentrations. To this
end, California revised the Building
Standards Code (Title 24) to require mechanical outdoor air ventilation systems
in all new homes built after Jan. 1, 2010.
While the new outdoor air ventilation
requirements are minimal (0.15 ACH),
this added ventilation will help reduce
indoor formaldehyde concentrations.
A more energy-efficient approach to
maintaining indoor formaldehyde concentrations at acceptable concentrations
is to reduce the amount of formaldehyde
emitted into homes. In April 2007, the
California Air Resources Board adopted