Environmental Engineering Reference
In-Depth Information
prevent contamination associated with building renovation and abatement
activities; and to reduce contaminant levels when screening measurements
or a building investigation reveal that a contaminant-related problem exists.
In the latter case, source control measures are implemented to mitigate an
existing problem.
I. Prevention
It is more desirable to prevent indoor contamination problems than to mit-
igate them once they have occurred. Such problems occur as a result of (1)
manufacturer inattention to, or denial of, potential health and safety prob-
lems involving the normal use of products; (2) consumer choices relative to
the use of products; (3) decisions made by facilities personnel and home-
owners; and (4) building design, construction, and operation and mainte-
nance practices.
A. Manufacturing safe products and product improvement
Many products are used to construct, furnish, and equip indoor environ-
ments. Most manufacturers do not knowingly (at least initially) produce
products that will pose minor or significant health risks to those who use
them. When health risks do occur, they are inadvertent or unintended. Some
products can be anticipated to pose potential health risks based on known
toxicities and exposure potentials associated with hazardous or toxic com-
ponents. Unfortunately, manufacturers did not address the potential health
risks associated with asbestos, lead, and formaldehyde (HCHO). As health
risks from exposures to such indoor contaminants became known, manufac-
turers often chose to deny that their products were harmful.
In the case of asbestos-containing building materials (ACMs) and lead-
based paints (LBPs), exposures in new buildings and houses were reduced
by regulatory prohibitions on the use of asbestos in building materials and
lead in paint. In the case of HCHO, exposures in new housing were reduced
as a consequence of regulatory limits on particle board and hardwood ply-
wood use in new mobile homes and by voluntary industry efforts to reduce
HCHO emissions from products.
Significant reductions in contaminant exposures can be achieved by the
development of low-emission or no-emission products. Such improvements
have been achieved for HCHO-emitting urea-formaldehyde-bonded wood
products by changing manufacturing processes. These included changes in
resin formulation and production variables, the addition of HCHO-scaveng-
ing compounds, attention to quality control, and use of various post-pro-
duction steps.
Significant reductions in HCHO emissions from wood products were
achieved by changing the molar HCHO-to-urea ratio (F:U) from 1.5:1 (com-
monly used in the 1970s and early 1980s) to 1.05:1. Additional reductions
were achieved by changing process variables to decrease wood moisture
