Environmental Engineering Reference
In-Depth Information
gypsum board panels. Because of cost factors and ease of installation, gyp-
sum board has dominated the construction market for interior wall and
ceiling covering for the past four decades, with plaster found primarily in
older homes. Gypsum board in itself appears to pose no direct IAQ/IE
concerns. However, during installation, spackling materials are used to cover
gaps between individual panels. Prior to 1980, most spackling compounds
contained asbestos; therefore, many older homes with gypsum board wall
covering contain a limited amount of asbestos fibers. In other older homes,
acoustical plaster containing 5 to 10% asbestos was sprayed on ceiling sur-
faces to provide a decorative finish with sound-absorbing properties.
Gypsum board has become increasingly associated with
Stachybotrys char-
tarum
is a fungus
that produces a potent mycotoxin (see Chapter 6 for an expanded discussion
of
infestations in residences and other buildings.
S. chartarum
). It grows readily on the cellulose face of gypsum board when
it has been subjected to a significant or repeated episodes of wetting.
Residential buildings have a variety of exterior and interior surfaces that
have been coated with paints, stains, varnishes, lacquers, etc. These coatings
may have significant emissions of volatile organic compounds (VOCs) and
semivolatile organic compounds (SVOCs), particularly when newly applied.
Old leaded paints (pre-1978) may pose unique indoor contamination prob-
lems (see Chapter 2).
Base gypsum board materials are usually finished with the application of
latex, or in some cases oil-based, paints. In the early history of a dwelling, latex
paints, though water-based, emit a variety of VOCs and SVOCs, with signifi-
cant emissions of VOCs and polyvalent alcohols from oil-based and latex
paints, respectively. Though these emissions diminish with time, high initial
emissions from walls and other painted surfaces represent a significant source
of odor, and in some cases irritant effects, in the early days of home occupancy.
Notably, some manufacturers have recently included biocides in their latex
paint formulations that emit significant quantities of formaldehyde in the first
weeks after application.
In some dwellings the base gypsum board may be covered, in whole or
in part, with decorative materials other than paint. These may include wall-
paper, hardwood plywood paneling, hardboard, vinyl, fabric, etc. Hardwood
plywood paneling may be used to cover walls in single rooms or, as was the
case in mobile homes, most rooms. Though gypsum board panels with a
paper or wallpaper overlay are now used most often, decorative hardwood
plywood paneling covered most interior walls of mobile homes constructed
in the U.S. prior to 1985. Hardwood plywood paneling was a potent source
of HCHO and a major contributor to elevated HCHO levels reported in
mobile homes constructed in the U.S. in the 1970s and early 1980s.
S. chartarum
7.
Energy conservation
Modern dwellings are being constructed to be more energy efficient. Energy
efficiency is achieved, in part, by using insulating materials such as fiberglass
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