Use of Non-Toxic or Less-Toxic Materials
Non- or less-toxic materials are less hazardous to construction
workers and a building’s occupants. Many materials adversely
affect indoor air quality and expose occupants to health hazards.
Some building materials, such as adhesives, emit dangerous
fumes for only a short time during and after installation;
others can contribute to air quality problems throughout a
building’s life.
Air Quality and Reduced Toxicity: The rush to make buildings
airtight in the wake of the 1970s oil crises created a new
health problem: “sick building syndrome.” This occurs when
natural or artificial ventilation is inadequate to remove odors
and chemicals emitted by certain building materials. These
substances may be hazardous, even carcinogenic. The resins
in plywood, particleboard, and the chemicals used in foam
insulation have been implicated in sick building syndrome.
Formaldehyde, benzene, ammonia, and other hazardous or
cancer-causing chemicals are present in many building
materials, furnishings, and cleaning solutions.
Previously, the infiltration rate of outside air through the gaps
and cracks in a building’s envelope compensated for contamination
of the inside air by human respiration, bacteria or
molds, and material emissions. The problem of indoor air
contamination is magnified by the increasing airtightness of
buildings. Super-insulating buildings in attempts to conserveenergy has caused reduced air infiltration, meaning occupants
are exposed to higher concentrations of toxins for longer time
periods. The health effects of these toxins must be considered
when selecting materials and calculating air exchange rates.
By selecting materials with lower or nonexistent levels of
these materials, environmental health problems can be
avoided and the need for expensive air scrubbers reduced.
Material toxicity is of increasing concern with the growing
number of building products containing petroleum distillates.
These chemicals, known as volatile organic compounds
(VOCs) can continue to be emitted into the air long after the
materials containing them are installed. The severity of this
process, called “outgassing,” is dependent on the chemicals
involved, rate emission, concentration in the air, and length
of exposure. Many adhesives, paints, sealants, cleaners, and
other common products contain VOCs. Often, the substances
are only exposed for a short time during and after installation;
the outgassing diminishes drastically or completely once the
offending materials have cured or been covered by other
building materials. Therefore, higher air cycling rates are
recommended during installation of these materials and for
several months following building occupation.