THE ANCILLARY HEALTH BENEFITS AND COSTS OF GHG MITIGATION: SCOPE, SCALE, AND ...

59 Pages·2000·0.27 MB·English

THE ANCILLARY HEALTH BENEFITS AND COSTS OF GHG MITIGATION: SCOPE,
SCALE, AND CREDIBILITY
by Devra DAVIS, Alan KRUPNICK and George THURSTON
Section 899 of the Code of Criminal Procedure for the State of New York, opens with the statement
that “persons pretending to foresee the future shall be deemed disorderly...”
1. Introduction
Climate change mitigation policies will bring with them ancillary or secondary benefits and costs in
addition to those directly associated with avoided temperature changes. The ancillary public health
effects of air pollutant emission changes (such as in reductions in particulate matter (PM)) have been
the focus of some research attention. However, none of the major economic models of climate
impacts has incorporated these ancillary impacts into their analyses. The extent and scale of ancillary
impacts will vary with the particular Greenhouse Gas (GHG) mitigation policy chosen. The
consideration of ancillary benefits can be of critical importance for devising optimal mitigation
strategies. To assist in the assessment of ancillary benefits, this paper examines literature relevant to
the assessment of ancillary benefits for public health of GHG policies and offers criteria for evaluating
this work.
A broad array of tools is required for the conduct of public health evaluations of ancillary costs and
benefits, and such tools are readily available. Energy scenarios can be employed to produce scenario
based risk assessments, which rely on emission inventories and air pollution and dispersion models.
Estimated changes in concentrations and exposures from these scenarios can then be linked in order to
estimate incremental changes in public health that could result from various GHG policies (Burtraw
et al., 1996, Cropper and Oates, 1992, Holmes et al., 1995, Jorgenson et al., 1995, Viscusi et al., 1994,
Burtraw and Toman, 1997, and Burtraw et al., 1999). In addition, a global assessment has been made
of the impacts on public health that could arise between 2000 and 2020 under current policies, and
under the scenario proposed by the European Union (EU) in 1995. (Working Group on Fossil Fuels,
1997, Davis, 1997). Country-wide assessments of GHG mitigation policies on public health have also
been produced for Canada (Last et al., 1998) and for China (World Bank, 1997), under differing
baseline assumptions.
In addition, there are numerous cost-benefit analyses that have been used to assess the public health
benefits of proposed environmental regulatory strategies (e.g., U.S. EPA, 1999, Thurston, et al, 1997).
Indeed, such cost-benefit analyses are required in the U.S. by Executive Order for major new
regulations. The public health effects of emissions changes in GHG co-pollutants is only one class of
many potential ancillary effects of GHG reduction policies. To estimate the entire array of ancillary
public health cost and benefits of alternative GHG mitigation strategies, a wide body of knowledge
and practice has been developed for potential application
At the same time, both the public health and the economics literatures are rife with ongoing
controversies. These include: the concentration-response functions being used (the appropriate
pollutants, the nature of and uncertainty about the functional relationships (e.g., whether thresholds
exist)) and, the valuation of various health endpoints (the appropriate estimates for the value of a
statistical life or statistical life year, for instance). Ideally, such cost-benefit studies should include
pollutants emitted into all environmental media, including air, water, and land. For instance, water
and soil pollution can arise from the deposition of combustion products from fossil fuels, such as
reactive sulfur and nitrogen compounds, which interact with naturally occurring humic materials,
phytochemicals and byproducts of chlorination to yield highly potent and reactive byproducts (Wu
et al., 1999). These byproducts can exacerbate water pollution and worsen water quality, causing
adverse impacts on human health.
Nevertheless, judging by the many past cost-benefit analyses of the effects of energy use on the
environment and health, the largest quantifiable category of ancillary benefits or costs is related to air
pollution and health effects. Of these, the largest contributor to the quantifiable monetary valuation of
health benefits involves mortality risks, while the numbers of estimated adverse effects are dominated
by less severe health outcomes.
While recognizing that air pollution is but one example of the potential auxiliary changes that will
accompany GHG mitigation policies, this paper attempts to clarify the weight of the evidence on the
important relationship between air pollution and health on the one hand, and health and economic
values on the other. Annex I presents a discussion of basic epidemiologic and economic concepts.
The body of this manuscript investigates, from the perspective of the health effects literature and the
valuation literature, several key aspects of this relationship:
• the scope of ancillary effects (Section 2) —which categories of health are likely to be affected
when carbon reduction policies are put in place, including both quantified and non-quantified
health effects, and which of these have been expressed in monetary terms;
• the scale of ancillary effects and benefits/costs (Section 3 for health effects, Section 5 for
valuation):
− –How large are these effects likely to be?
− –What is the population at risk?
− –How large are the monetary values of these effects?
• The credibility of these estimates (Section 4 for health effects; Section 6 for valuation). What
are the strengths, weaknesses, limitations and uncertainties characterizing the relationships
between pollution and health and for the various methods of estimating the economic
valuation of these effects?
We close with recommendations to policymakers and modelers on the appropriate role of ancillary
health benefits and costs in the climate change mitigation debate and supporting modeling. As part of
these recommendations, we also identify a number of public health and economic related research
topics that require clarification in order to promote the more effective conduct of ancillary benefits
assessments with respect to GHG mitigation policies. See Annex I for a discussion of basic
epidemiologic and economic concepts.
2. Scope of ancillary benefits
2.1 Health effects
Most of the research that has quantified health effects linked with air pollution extends across the
entire human age range. Considerable numbers of human studies have been conducted for the
commonplace “community” air pollutants. As a result, there is a large and rapidly growing number of
studies linking air pollution with both mortality and morbidity throughout the world. A broad
consensus has emerged over the past 5 decades showing that ambient levels of pollution in developed
countries today are linked with measurable impacts on public health. Public health disasters, such as
the episodes that occurred in London, 1952 and Donora, 1948, provided unambiguous proof of the
damaging potential of high levels of air pollution for public health.
More recently, sophisticated time series analyses of daily pollution patterns, along with cross-sectional
and cohort studies of differences in rates of chronic and acute illness, have provided a consistent
picture of the extent to which ambient levels of air pollution affect severe health outcomes, including
mortality and hospital admissions. But, as displayed in Figure 1 for the city of New York, these
routinely recorded severe health outcomes represent only the “tip of the iceberg” of adverse effects
associated with this pollutant. They are best viewed as indicators of the much broader spectrum of
adverse health effects, such as increased restricted activity days and doctors visits, being experienced
by the public as a result of air pollution exposures. Although these outcomes have much lower
“monetary valuations” than the more severe impacts, their presence is important to recognize when
gauging the scope of air pollution’s impact on society.
Figure 1. Pyramid of New York City, NY Annual Adverse Ozone Impacts avoided by the
implementation of the proposed new standard (vs. “AsIs”)*
Asthma Hospital Admissions/yr. 75 Deaths/yr
(0.01% of all adverse impact cases)
Non-asthma Respiratory
265 240 Hospital Admissions/yr
3,500

Respiratory
ED Visits/yr
180,000

Asthma Attacks/yr
(i.e., person-days during which notably
increased asthma symptoms, e.g.,
requiring extra medication, are experienced)
930,000

Restricted Activity Days/yr
(i.e., person-days on which activities
are restricted due to illness )
2,000,000

Acute Respiratory Symptom Days/yr
(i.e., person-days during which respiratory symptoms such as
chest discomfort, coughing, wheezing, doctor diagnosed flu, etc.
are experienced)

*Figure section sizes not drawn to scale.
Source: Ozone and Particulate Matter Standards: Hearings on the Clean Air Act Before the
Subcommittee on Clean Air, Wetlands, Private Property and Nuclear Safety and the Comm.
on Env’t and Public Works, 105th Congress (1997).
A summary of the presently quantifiable and the suspected effects of ambient air pollution on human
health are summarized in Table 1. From this table, it can be seen that any air pollution impact
assessment, especially in terms of numbers of health effects, will not be able to quantify the full range
of changes in health effects that will result from changes in the levels of ambient air pollution.
The very young, older adults, and persons with pre-existing respiratory and cardio-vascular disease are
among those thought to be most strongly affected by air pollution. Airway inflammation induced by
ozone and PM is especially problematic for children and adults with asthma, as it makes them more
susceptible to having asthma attacks, consistent with recent asthma camp results (Thurston,
et al., 1997). For example, controlled human studies (e.g., Molfino et al., 1991) have indicated that
prior exposure to ozone enhances the reactivity of asthmatics to aeroallergens, such as pollens, which
can trigger asthma attacks. In addition, ozone increases inflammation and diminishes immune
function the lungs. This can make older adults more susceptible to pneumonia, a major cause of
illness and death in this group.
Table 1. Scope of health effects
Human Health Effects of Air Pollution
Quantifiable Health Effects Non-quantified/Suspected Health Effects
Mortality* Neonatal and post-neonatal mortality
Bronchitis - chronic and acute Neonatal and post-neonatal morbidity
Asthma attacks New asthma cases
Respiratory hospital admissions Fetus/child developmental effects
Cardiovascular hospital admissions Non-bronchitis chronic respiratory diseases
Emergency room visits for asthma Cancer (e.g., lung)
Lower respiratory illness Behavioral effects (e.g.,.learning diabilities)
Upper respiratory illness Neurological disorders
Shortness of breath Respiratory cell damage
Respiratory symptoms Decreased time to onset of angina
Minor restricted activity days Morphological changes in the lung
All restricted activity days Altered host defense mechanisms
Days of work loss (e.g., increased susceptibility to respiratory infection)
Moderate or worse asthma status Increased airway responsiveness to stimuli
Exacerbation of allergies
Source: Adapted from: The Benefits and Costs of the Clean Air Act 1990 to 2010, U.S. EPA,
EPA-410-R-99-001 1999).
It is well established that both asthma mortality and asthma hospital admissions increased during the
1980’s in the U.S. and other developed nations (e.g., Buist and Vollmer, 1990; Taylor and
Newacheck, 1992). The highest rates are associated with inner city residence (Carr et al, 1992; Weiss
and Wagener, 1990), and Latino or African-American origin (Carter-Pokras and Gergen,
1993; Coultas et al, 1993; Weiss and Wagener, 1990). Conventional air pollutants do not appear to
be the driving force behind the global increase in the prevalence of asthma, since levels of
conventional pollutants have generally declined while the asthma prevalence has increased. However,
because more persons are acquiring asthma, an ever increasing number in the population will be
affected by the aggravating effects of air pollution, especially among the economically disadvantaged.
In many different regions of the world, studies have found a higher rate of hospitalizations for asthma
in more polluted zones. For example, the chance of being hospitalized with asthma on days following
high air pollution in New York City is much greater than in the surrounding suburbs, probably because
the city has a much larger minority and low-income population (Thurston et al., 1992, Saldiva et al.,
1996). In the words of Weiss and Wagener (1990), “whatever the reason for the increases, both
asthma mortality and hospitalization continue to affect non-whites, urban areas, and the poor
disproportionately. For example, the hospitalization rate for asthma is higher in New York City than
anyplace else in the U.S. (Carr et al., 1992).
Among the factors that may increase the susceptibility of residents of low-income urban
neighborhoods to air pollution are:
i. Enhanced individual susceptibility of minority populations to pollution
effects (i.e., more compromised health status, due to genetic predisposition,
impaired nutritional status, or severity of underlying disease);
ii. Exposures to atmospheric pollution in center cities may be greater than
those of the general population, due to higher local pollutant emissions
combined with a lower prevalence of protective air conditioning;
iii. Potentially enhanced exposures to a variety of residential risk co-factors
such as cockroaches, dust mites, and indoor pollution sources (e.g., gas stoves
used for space heating purposes); and/or
iv. A greater likelihood of poverty, which is associated with reduced access to
routine preventive health care, medication, and health insurance.
A number of studies suggest that the very young represent an especially susceptible sub-population,
although the precise magnitude of the effects of specific levels of air pollution can be expected to vary
with other underlying conditions. Lave and Seskin (1977) found mortality among those 0-14 years of
age to be significantly associated with levels of total suspended particulates (TSP). More recently,
Bobak and Leon (1992) studied neonatal (ages less than one month) and post-neonatal mortality (ages
1-12 months) in the Czech Republic, finding significant and robust associations between post-neonatal
mortality and PM , even after considering other pollutants. Post-neonatal respiratory mortality
10
showed highly significant associations for all pollutants considered, but only PM remained
10
significant in simultaneous regressions. Woodruff et al. (1997) used cross-sectional methods to
follow-up on the reported post-neonatal mortality association with outdoor PM pollution in a U.S.
10
population. This study involved an analysis of a cohort consisting of approximately 4 million infants
born between 1989 and 1991 in 86 U.S. metropolitan statistical areas (MSAs). After adjustment for
other covariates, the odds ratio (OR) and 95% confidence intervals for total post-neonatal mortality for
the high exposure versus the low exposure group was 1.10 (CI=1.04-1.16). In normal birth weight
infants, high PM exposure was associated with mortality for respiratory causes (OR = 1.40,
10
CI=1.05-1.85) and also with sudden infant death syndrome (OR = 1.26, CI=1.14-1.39). Among low
birth weight babies, high PM exposure was associated, but not significantly, with mortality from
10
respiratory causes (OR = 1.18, CI=0.86-1.61).
This study was recently corroborated by a more elegant follow-up study by Bobak and Leon (1999),
who conducted a matched population-based case-control study covering all births registered in the
Czech Republic from 1989 to 1991 that were linked to death records. They used conditional logistic
regression to estimate the effects of suspended particles, sulfur dioxide, and nitrogen oxides on risk of
death in the neonatal and post-neonatal period, controlling for maternal socioeconomic status and birth
weight, birth length, and gestational age. The effects of all pollutants were strongest in the
post-neonatal period and were specific for respiratory causes. Only particulate matter showed a
consistent association when all pollutants were entered in one model. Thus, populations with
relatively high percentages of children may have higher air pollution effects than in populations in
study areas with fewer children (e.g., studies conducted more developed nations).
2.2 Scope for valuation
The literature reviewed above indicates that a wide variety of possible health endpoints could be
affected ancillary to climate change mitigation policies. Some of these have not been quantified, and
some of the effects listed as non-quantified may be related physiological expressions of those that are
quantified. Of the quantified endpoints, Table 2 provides information about whether they have been
(or could be) monetized, based on our understanding of the literature. We also consider the status of
monetization for some of the non-quantified health effects. For each of these effects, we list the
techniques used to provide monetary values. Willingness to Pay studies (WTP) are those that provide
estimates of preferences for improved health that meet the theoretical requirements of neoclassical
welfare economics. Cost of Illness (COI) is a technique that involves totaling up medical and other out
of pocket expenditures. “Consensus” refers to the way in which these values were determined. They
do not have much of an evidentiary basis. Each of these approaches and endpoints are discussed in
more detail in Section 6.
The valuation literature for neonatal mortality, children, and cancer is very limited at the present time,
but there is much interest in better valuing these endpoints in the U.S. Cancer valuation is discussed in
Section 6. Valuing reduced mortality risks for newborns or children is one of the most challenging
tasks in the field because children are generally not the key decision makers over their own health and
safety. They are part of a family unit that makes choices for them. For this reason, some economists
are devising household production function models to address these valuation questions (Tolley,
1999; Dickie, 1999) and devising novel strategies for measuring revealed preferences for improving
child safety and health (such as examining the types of vehicles or bicycle helmets purchased).
However, this literature has not yet matured.
In addition, we add here placeholders for two potentially important linkages that go from economic
effects of GHG policies to health effects rather than the reverse. The linkage from unemployment to
health refers to the possibilities that GHG policies might raise or lower unemployment rates from what
they would otherwise be. A number of studies have linked unemployment to increased suicides,
domestic violence, and alcohol and drug abuse. While this linkage is quite controversial in the health
benefits literature, it has the potential to introduce a large, new set of ancillary benefits (or costs) to
such studies. The second linkage — from lower incomes to lower health status — is of a similar type.
GHG policies may lower incomes below BAU levels. A number of studies have shown how income is
positively correlated with health status. Thus, if incomes fall or do not rise as fast as a result of a
GHG policy, health may worsen absolutely or relative to what it would have been in the absence of a
GHG policy. Again, this linkage is quite controversial, and is included here because of its potential to
change thinking on the ancillary benefits/costs issue.
Table 2. Status of valuation of quantified and suspected health endpoints
Health Effects Valuation Basis
Estimates
Available?
QUANTIFIED EFFECTS
Mortality: Adults Y WTP (caveats)
Chronic Bronchitis Y WTP (caveats)
Acute Bronchitis Y COI
Hospital Admissions Y Hospital Costs
Emergency room visits Y Emergency room costs
Lower respiratory illness Y WTP (caveats)
Upper respiratory illness Y WTP (caveats)
Respiratory symptoms Y WTP
MRAD Y Consensus
RAD Y Consensus
WLD Y Wage
Asthma Day Y WTP
Change in asthma status N
NON-QUANTIFIED/SUSPECTED EFFECTS
Mortality: Neonatal/fertilit Y WTP; Number of
y studies on-going
Mortality: Children Soon Number of WTP
studies on-going
Cancer Mortality and Y COI; WTP
Morbidity (various types)
LINKS FROM ECONOMIC EFFECTS TO HEALTH
Health effects linked to ? ?
unemployment
Health effects linked to ? ?
lower incomes
3. Scale of health effects
Observational epidemiology studies - both long-term and acute exposure studies - have shown
compelling and remarkably consistent evidence of air pollution associations with adverse human
effects, including: decreased lung function, more frequent respiratory symptoms, increased numbers
of asthma attacks, more frequent emergency department visits, additional hospital admissions, and
increased numbers of daily deaths. While not all of these impacts represent major financial impacts on
the society, they often involve decreases in quality of life, and also provide additional weight of
evidence of air pollution associations with the most serious effects, such as mortality.
In studies to date, the health effects associated with particulate matter (PM) and ozone (O ) have
3
consistently been found. Particulate matter consists of two types of particles: primary and secondary
particles. Primary particles come directly out of the tailpipes and stacks, and those are primarily
carbonaceous particles. Secondary particles are formed in the atmosphere from gaseous pollutants,
such as sulfates from sulfur dioxide and nitrates from nitrogen oxides (NO ). Ozone (O ) is an
x 3
invisible irritant gas that is formed in the atmosphere in the presence of sunlight and other air
pollutants. These ozone precursor pollutants, nitrogen oxides and hydrocarbons, as well as SO , come
2
from a variety of sources, including diesel automobiles (diesel contains more sulfur than gasoline),
power plants, and industry.
As shown in Figures 2-5, there have been numerous studies published in recent years indicating
consistent associations between both PM and O exposures and both daily mortality and morbidity. It
3
is interesting to note that the inclusion of PM along with ozone in the model has little effect on the
O -mortality effect, indicating that these associations are likely to be largely independent of one
3
another.
Figure 2. Ozone mortality effect estimates across localities, with and without simultaneous
inclusion of PM
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