lives lost as is the typical approach used by the
USEPA.
A key consideration as to whether these benefits
can be realized relates to whether the roll-back in
air concentrations that is assumed in the analysis as
a result of the new standard can actually be realized. In part, this relates to how realistic the
assumptions have been with regard to background
levels. The analysis of benefits of reducing a given
pollutant, say Ozone, becomes even more convoluted when the analysis includes postulated reductions in a second pollutant, such as particulate
matter, associated with achieving the Ozone Standard. A discussion of this issue for Ozone can be
found in McClellan et al. [43]. Indeed, as the levels
of the standards are ratchetted down toward background levels, there is increasing uncertainty as to
whether there are any health effects attributable to
single pollutants and even greater uncertainty as
to the magnitude of the health benefits associated
with any new lower standard. The use of single
pollutant models for estimating benefits raises the
issue of double-counting of benefits as the benefits
of the individual pollutants are aggregated.
Hence, the paradigm shift. It is apparent that in
setting the earliest NAAQS some individuals,
including CASAC members, envisioned that the
standards were being set at levels protective of public health with an adequate margin of safety based on
threshold ambient concentration-response models.
In short, if there were health effects at the level and
form of the NAAQS, they were de minimis. It is
useful to recall the Editorial by Kennedy [27]. In
contrast, more recent NAAQS have been set at
levels which both the CASAC and EPA characterize
as having residual health effects even if the standard
were to be attained. The central question remains –
how low is low enough? I view the answer as a
policy judgment informed by science that can only
be made by the EPA Administrator [41].
WHO Process for Setting Air Quality
Guidelines
The approach taken by the World Health Organization (WHO) contrasts with the USEPA approach.
WHO was established in 1948 as a specialized
Agency of the United Nations to be the directing
and coordinating authority for international health
matters and public health. WHO develops air quality guidelines (AQG) designed to offer guidance in
reducing the health impacts of air pollution. The
first AQG were produced in 1987 [94]. Updates
were published in 2000 and 2005 [95, 96]. The
AQG are intended to inform policymakers and to
provide appropriate targets for a broad range of
policy options for air quality management in different parts of the world, despite the more recent
documents being titled AQG for Europe.
The WHO AQGs are developed by working
groups of scientific experts [95, 96]. In addition to
preparing AQG for the classical air pollutants
(Particulate matter, Ozone, Nitrogen dioxide, and
Sulfur dioxide) the WHO also developed AQG for
(a) inorganic air pollutants, (b) certain indoor air
pollutants, (c) polychlorinated biphenyls, dioxins,
and furans, and (d) volatile organic compounds. The
WHO AQG process does not include any opportunity for the involvement of interested parties such as
the public, national governments, nongovernmental
organizations, or industry. They represent expert
judgment exercised by scientists knowledgeable of
the subject material. This approach contrasts
sharply with the more formal and complex approach
followed by the US Environmental Protection
Agency in developing NAAQS.
The primary aim [95] of the AQG is “to provide a uniform basis for the protection of public
health and ecosystems from adverse effects of air
pollution and to eliminate or reduce to a minimum
exposure to those pollutants that are known or
likely to be hazardous.” “They have the character
of recommendations, and it is not intended or
recommended that they simply be adopted as
standards.” The WHO [95] report notes:
In the process of moving from a “guideline” or a
“guideline value” to a “standard,” a number of
factors beyond the exposure-response relationship
need to be taken into account. These factors include
current concentrations of pollutants and exposure
levels of a population, the specific mixture of air
pollutants, and the specific social, economic and
cultural conditions encountered. In addition, the
standard-setting procedure may be influenced by
the likelihood of implementing the standard.
These considerations may lead to a standard above
or below the respective guideline value.
Air Quality Guidelines and Standards
25
USEPA.
A key consideration as to whether these benefits
can be realized relates to whether the roll-back in
air concentrations that is assumed in the analysis as
a result of the new standard can actually be realized. In part, this relates to how realistic the
assumptions have been with regard to background
levels. The analysis of benefits of reducing a given
pollutant, say Ozone, becomes even more convoluted when the analysis includes postulated reductions in a second pollutant, such as particulate
matter, associated with achieving the Ozone Standard. A discussion of this issue for Ozone can be
found in McClellan et al. [43]. Indeed, as the levels
of the standards are ratchetted down toward background levels, there is increasing uncertainty as to
whether there are any health effects attributable to
single pollutants and even greater uncertainty as
to the magnitude of the health benefits associated
with any new lower standard. The use of single
pollutant models for estimating benefits raises the
issue of double-counting of benefits as the benefits
of the individual pollutants are aggregated.
Hence, the paradigm shift. It is apparent that in
setting the earliest NAAQS some individuals,
including CASAC members, envisioned that the
standards were being set at levels protective of public health with an adequate margin of safety based on
threshold ambient concentration-response models.
In short, if there were health effects at the level and
form of the NAAQS, they were de minimis. It is
useful to recall the Editorial by Kennedy [27]. In
contrast, more recent NAAQS have been set at
levels which both the CASAC and EPA characterize
as having residual health effects even if the standard
were to be attained. The central question remains –
how low is low enough? I view the answer as a
policy judgment informed by science that can only
be made by the EPA Administrator [41].
WHO Process for Setting Air Quality
Guidelines
The approach taken by the World Health Organization (WHO) contrasts with the USEPA approach.
WHO was established in 1948 as a specialized
Agency of the United Nations to be the directing
and coordinating authority for international health
matters and public health. WHO develops air quality guidelines (AQG) designed to offer guidance in
reducing the health impacts of air pollution. The
first AQG were produced in 1987 [94]. Updates
were published in 2000 and 2005 [95, 96]. The
AQG are intended to inform policymakers and to
provide appropriate targets for a broad range of
policy options for air quality management in different parts of the world, despite the more recent
documents being titled AQG for Europe.
The WHO AQGs are developed by working
groups of scientific experts [95, 96]. In addition to
preparing AQG for the classical air pollutants
(Particulate matter, Ozone, Nitrogen dioxide, and
Sulfur dioxide) the WHO also developed AQG for
(a) inorganic air pollutants, (b) certain indoor air
pollutants, (c) polychlorinated biphenyls, dioxins,
and furans, and (d) volatile organic compounds. The
WHO AQG process does not include any opportunity for the involvement of interested parties such as
the public, national governments, nongovernmental
organizations, or industry. They represent expert
judgment exercised by scientists knowledgeable of
the subject material. This approach contrasts
sharply with the more formal and complex approach
followed by the US Environmental Protection
Agency in developing NAAQS.
The primary aim [95] of the AQG is “to provide a uniform basis for the protection of public
health and ecosystems from adverse effects of air
pollution and to eliminate or reduce to a minimum
exposure to those pollutants that are known or
likely to be hazardous.” “They have the character
of recommendations, and it is not intended or
recommended that they simply be adopted as
standards.” The WHO [95] report notes:
In the process of moving from a “guideline” or a
“guideline value” to a “standard,” a number of
factors beyond the exposure-response relationship
need to be taken into account. These factors include
current concentrations of pollutants and exposure
levels of a population, the specific mixture of air
pollutants, and the specific social, economic and
cultural conditions encountered. In addition, the
standard-setting procedure may be influenced by
the likelihood of implementing the standard.
These considerations may lead to a standard above
or below the respective guideline value.
Air Quality Guidelines and Standards
25