Environmental Engineering Reference
In-Depth Information
Estimating the ancillary public health consequences of GHG policies is a challenging task,
drawing upon expertise in economics, emission inventories, air pollution modeling, and public
health. However, most assessments to date have focused more heavily on one aspect of the frame-
work (i.e., a portion of Figure 13.4), whether it be estimation of changes in air pollutant concentra-
tions, health response, or economic analysis.
Results from current ancillary beneits studies may be underestimates due to unquantiied
beneits, as only a subset of the health consequences from air pollution have adequate exposure-
response relationships (Voorhees et al., 2001; Committee on Estimating the Health-Risk-Reduction
Beneits of Proposed Air Pollution Regulations, 2002; USEPA, 2005; Voorhees, 2005). A USEPA
evaluation of the Clean Air Interstate Rule (CAIR) noted numerous unquantiied health impacts
such as chronic respiratory damage for ozone (O 3 ), loss of pulmonary function for PM, and lung
irritation for nitrogen oxide (NO x ) (USEPA, 2005). The nature of unquantiied effects is continually
evolving. Some pollution and health relationships considered unquantiiable by USEPA (1999) have
since been identiied, such PM air pollution's association with lung cancer (Filleul et al., 2005;
Krewski et al., 2005). Furthermore, some endpoints may be included in one analysis, but regarded
as too uncertain for another, perhaps due to a different study location or differences in researchers'
judgment. One approach to addressing health endpoints with uncertain concentration-response
functions is to include these effects qualitatively in discussion of unquantiied beneits. Another is
to incorporate these effects within a sensitivity analysis.
Valuations of mortality risk reductions associated with environmental policies are usually the
largest category of beneits, both among health responses and compared to other attributes. For
instance, a USEPA analysis of the Clean Air Act estimated a value of $100 billion annually for
reduced premature mortality out of $120 billion in total beneits, compared to costs of approxi-
mately $20 billion (USEPA, 1999). European and Canadian studies similarly found that mortality
risk dominates analysis of pollution reductions (Stratus Consulting, 1999; Bickel and Friedrich,
2005). Next to mortality, reductions in the probability of developing a chronic respiratory disease
have been estimated to have the highest monetary value, recognizing that values for other types of
diseases are sparse.
Recently, the Stern Review (Stern, 2007) addressed a wide range of global beneits and costs
associated with climate change, including air pollution co-beneits. Citing a study by the European
Environmental Agency, the Review notes that limiting global mean temperature increase to 2°C
would lead to annual savings in the implementation of existing European air pollution control mea-
sures of €10 billion and additional avoided annual health costs of €16-€46 billion. Even larger
co-beneits are estimated in developing countries, including via the substitution of modern fuels for
biomass. The Stern Review also recognizes some of the trade-offs between climate change objec-
tives and local air quality gains. For instance, switching from petrol to diesel reduces CO 2 emissions
but increases pPM 10 and NO x emissions. Other GHG mitigating actions present fewer environmen-
tal trade-offs (e.g., reductions in aircraft weight can decrease CO 2 emissions and simultaneously
improve local air quality).
Overall, although still a work in progress, the present techniques available for the analyses of the
ancillary public health costs and beneits are adequate and appropriate for implementation by those
comparing the relative merits and overall value of various GHG mitigation policies. Estimates of
considerable beneits that remain after a variety of sensitivity analyses can alleviate some concerns
regarding limitations of individual methods or assumptions. The PM air-pollution-associated public
health changes associated with GHG mitigation strategies should be a key factor in the choice of
GHG policies.
13.6  IMPLICATIONS
The most recent Intergovernmental Panel on Climate Change (IPCC) (2007) report has concluded,
in the most deinitive terms yet, that global climate change is occurring, stating that “[w]arming
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