Environmental Engineering Reference
In-Depth Information
are also used to achieve ambient AQSs. Depending on existing air quality,
emission standards on individual sources may vary from place to place.
1.
Product emissions
An emission standard is a numerical limit on the quantity of a contaminant
that can be emitted from a source per unit time (e.g., lbs/hr, gm/sec, etc.). A
variant of the emission standard concept has been used to control HCHO
emissions from urea-formaldehyde (UF)-bonded wood products such as par-
ticle board and decorative wood paneling produced for use in the construction
of mobile/manufactured homes in the U.S. These limits are better described as
product standards. They are not specified as an emission rate (e.g., mg/m
/hr)
but as the maximum acceptable air concentration in a large, environmentally
controlled chamber at a loading rate (m
2
) typical of a mobile home envi-
ronment. Product standards are used in western and north European countries,
e.g., Germany, Denmark, and Finland, to conform with indoor air guideline
values for HCHO (see Section IV.A).
Product standards have considerable potential for improving air quality
in buildings and other environments. They could conceivably be used to limit
emissions of volatile and semivolatile organic compounds (VOCs and SVOCs)
from products such as carpeting, vinyl floor and wall coverings, paints, var-
nishes, lacquers designed for indoor use, adhesives and caulking compounds
used in building construction, and coating materials used in arts and crafts.
Product standards in the regulatory context have a very important
attribute; they are relatively simple to implement, administer, and assess
compliance. The burden of compliance is placed on manufacturers, who
must verify that their product meets emission limits before the product is
sold. A special application of the product standard concept has been
employed by the state of Washington in its office building construction
program. Vendors who contract with the state must provide products that
do not exceed an air concentration of 0.05 ppmv HCHO, 0.5 mg/m
/m
2
3
TVOCs,
3
1 ppbv 4-PC and 50
ยต
g/m
particles at the anticipated loading conditions
3
(m
) within 30 days of installation. In addition, any substance regulated
as an ambient air pollutant must meet emission limits that will not exceed
the USEPA's primary or secondary AQSs, and one tenth the Threshold Limit
Value (ACGIH occupational guideline value for an 8-hour time-weighted
exposure) of other substances of concern.
/m
2
3
2.
NSPSs for wood-burning appliances
USEPA's emission standard program for new ambient sources (NSPS) has
had an unintended but positive impact on IAQ. USEPA, in an attempt to
reduce the impact of wood-burning appliance emissions on ambient air
quality, promulgated an NSPS for wood-burning stoves to reduce emissions
of PM
(particles) and CO. These performance standards, applied nation-
wide, have had the effect of improving the emission performance of all new
wood-burning stoves to both the ambient and indoor environments.
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