Environmental Engineering Reference
In-Depth Information
HCHO IAQ standard in new mobile homes. As a result of industry lobbying
efforts, the state legislature significantly weakened (to 0.5 ppmv) the stan-
dard. In another instance, the Department of Housing and Urban Develop-
ment (HUD) used a target level of 0.4 ppmv HCHO as a
standard,
claiming (without benefit of a risk assessment) that it provided reasonable
health protection to occupants of new mobile homes. Scientific studies, how-
ever, have shown that HCHO exposures well below 0.4 ppmv may cause
serious health effects in those exposed in residential environments.
Standards, as interpreted by many professionals and the lay public,
convey a perception of implicit safety when measured values are below the
standard and implicit danger if above the standard. These perceptions result
in a false sense of security in the former case, and excessive fear in the latter.
The true nature of a standard, incorporating the uncertainties and political
compromises involved, is generally not understood.
Compliance with ambient AQSs is determined by monitoring commu-
nity air in fixed sampling locations and/or modeling specific sources.
Though manageable, monitoring ambient air quality to assess compliance
with AQSs requires significant personnel and resources; this is true when
evaluating compliance with most environmental standards.
Assessing compliance with IAQ standards would pose significant diffi-
culties in its implementation due to the enormous resource requirements as
well as a variety of practical problems. If applied to residences, effective
monitoring using dynamic integrated sampling would be intrusive and, in
many cases, homeowners would not be receptive to it. Passive monitoring
would be less intrusive but less reliable. Results would depend on the integrity
of those using the passive monitoring equipment. In addition to intrusiveness,
privacy issues, property rights, and maintaining the integrity of passive sam-
plers, it would be physically impossible to monitor compliance for even one
contaminant in a targeted subset of 80+ million residences in the U.S.
Monitoring public-access buildings would be a less formidable under-
taking. It would pose fewer privacy and access issues and there would be
fewer buildings to monitor. Nevertheless, the task would still be enormous
and could not be achieved without requiring building owners to take on the
task themselves. An AQS approach to control air quality in buildings would
require that standards be self-enforced, as has been the case for smoking
restrictions. Though the latter has been effective, it would likely be less
effective in the case of IAQ standards.
de facto
B.
Emission standards
Emission standards are used in ambient air pollution control programs to
control emissions from all new or significantly modified existing sources
(New Source Performance Standards, NSPS) and have been used for pollut-
ants regulated under National Emissions Standards for Hazardous Air Pol-
lutants (NESHAP). In both cases, emission limits are uniform for all sources
in a source category, regardless of air quality in a region. Emission standards
