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IMPACT OF INCREASED USE OF COAL
ON HEALTH AND THE ENVIRONMENT
L.A. Sagan, M.D.
Electric Power Research Institute
Palo Alto, CA
Introduction
The United States - and the world in general - can anticipate
a tremendous increase in the use of coal over the next 20 years.
In the early 1970s, economists and energy people were suggesting
that coal use in America could double by the year 2000. Now,
estimates of a tripling by 2000 are commonly heard. Even with a
"no growth" economy, the United States will need an additional 30
quads (1 quad = 1015BTU) of energy by 2000. That additional
energy will almost certainly come from some combination of coal
and nuclear plants. Signs now point to coal shouldering the major
burden of that need.
The contribution from geothermal or solar technologies cannot be
expected to be significant over the next 20 years. Under any energyuse projection, coal plays a significant role, and at least a doubling
of coal use by the end of the century seems likely.
A marked increase in the use of coal is certain to raise a number
of national concerns - from problems of reclaming mining areas to
questions about pulmonary dysfunction and air pollution. As a
nation we must face these questions of environmental effects of
increased use of coal. Certainly, an increase in coal use has the
potential for causing a wide range of undesirable effects. This paper
will deal with only one aspect of coal use, the effects on the environment especially those related to atmospheric emissions.
A major problem in discussing the environmental effects of increased coal use is the absence of enough data to document effects
from present use. This is particularly true for questions about atmospheric pollution. We can see the effect of strip-mining on soil
cover. We can tabulate the number of fatalities due to mine accidents. We can estimate the incidence of coal workers' pneumoconiosis. We have difficulty, however, in assessing the quantitative
effect of stack emissions on population mortality or morbidity.
Similarly, we cannot yet define the utilities' contribution to acidic
precipitation or to visibility degradation.
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Because of our inability to assess quantitatively the present impact
of coal use on the environment, we are in no position to state with
certainty the consequences of a two-fold or three-fold increase in
coal burning. At best, we can point out general areas of concern
and give an indication of what specific problems society may be
facing. Such will be the approach used in this paper. The areas of
concern to be considered are health effects, ecological damage,
visibility degradation, and climatic change.
Human Health Effects
Expansion in coal combustion has led some investigators to predict
significant health impacts on the general population. This must be
considered if coal combustion is to be increased substantially. In
these assessments only the effects of combustion of fossil fuel
products were considered. Not considered were the sizable penalty
of increased injuries and deaths in that most dangerous of occupations - coal mining, and the injuries and deaths associated with
both the transportation of coal over long distances, and the construction of massive coal-burning facilities.
The two products of fossil fuel combustion which appeared to
be of greatest concern to these investigators were sulfur dioxide
(SO2 ) and particulate matter, especially sulfates. Based on increased
emissions of SO2 and particulates, predictions have been made that
significant effects on human health - particularly premature mortality - may be expected as a consequence. This, in part, is based
upon historical experience. The fact that air pollution could adversely affect human health is a relatively recent concept. A most
dramatic and well known example occurred in December 1952 in
London when, during a week-long atmospheric inversion, combustion products were trapped near ground level and smoke and SO 2
(the only two pollutants then being measured) rose markedly.
Concomitant with the rise in combustion products, daily deaths
jumped from the normally anticipated 250 per day to over 800.1
During the week long inversion episode 4,000 more persons died
than would normally have been expected to do so in that time period.
Virtually all of these deaths occurred in persons with chronic cardiac
and pulmonary disease whose respiratory tracts were already severely
compromised. The deaths, in almost all cases, could be considered
only an acceleration of a process already well underway.
Nevertheless, the fact that air pollution could precipitate premature mortality was dramatically illustrated, and led to the passage
of a Clean Air Act designed to reduce the likelihood of subsequent
episodes. In 1956 a Clean Air Act was passed in Britain requiring
the introduction of cleaner fuels low in volatile matter and particulates. No attempt was made to limit either ambient air concentration of SO2 or the amount of sulfur contained in the fuels used.
62
This resulted in a dramatic reduction in the smoke and smog traditionally considered part of the London scene.
It is noteworthy that although smoke (particulate matter) measure
in micrograms per cubic meter fell rapidly after the passage of the
British Clean Air Act, a steady decrease in smoke had been in effect
for many years previously as more efficient heating devices had
been introduced into British homes. Although particulate matter
consistently fell, SO 2 which the British made no effort to control,
also decreased but to a much lesser extent. In part this was due to
the lower sulfur content of the cleaner fuels used in British home
fireplaces, but also because a decrease in smoke allowed greater
penetration of sunlight with ground warming and dispersion of
atmospheric inversion conditions.
A natural experiment occurred exactly 10 years later in London
when in 1962 atmospheric conditions similar to those of December
1952 obtained and concentrations of SO 2 rose to almost identical
levels. However, the smoke (i.e., particulate) levels during the 1962
fog were much lower. The premature deaths in 1962 were limited
to 700 as opposed to 4,000 in 1952.2 Today with introduction of
cleaner anthracite and a considerable amount of centralized heating,
both smoke and SO2 levels have been reduced to a point where no
further correlation can be discerned between respiratory disease or
deaths and the varying peaks of air pollution that occur several times
each year in London.
It is important to note that the earliest measures of air pollution
were of SO 2 . This was measured by decolorization of potassium
iodide, and of particulates measured either as total particulates
gathered by a high volume sampler over a 24 hour period, or as
smoke shade measuring smaller particulates in the respirable range.
These substances were monitored during the previously described
acute pollution episodes when premature mortality was observed,
and because simple techniques existed for their measurement. They
were, however, by no means the sole constituents of the pollution
prevailing throughout industrial conurbations.
Obviously many substances are released during fossil fuel burning.
These include carbon dioxide, sulfates, oxides of nitrogen, nitrates,
and numerous trace elements in varying chemical composition
depending upon the composition and combustion conditions of
the fossil fuel being burned. To these must be added the numerous
effluents derived from industrial processes in the same area. Pollutants also are generated by the general activity of the population
including transportation, space heating, and cooking.
It was assumed by the earliest investigators that the two pollutants
most easily monitored (SO 2 and particulates) could be expected to
bear a linear relationship to the presence of all these other compounds. Sulfur dioxide, and/or particulates, were thus used as
63
surrogates for general atmospheric pollution. As time passed the
continued reporting of air pollution levels in terms of SO 2 and
particulates spread the impression - not intended by the pioneering
investigators - that these compounds themselves were responsible
for the health effects observed. This assumption led to serious errors
in assessment of health effects of air pollution, and to drastic, and
probably unnecessarily strict regulation of SO 2 emissions.
Both animal toxicologic and controlled human experiments do
demonstrate transient changes in pulmonary function on exposure
to SO2 levels at five to ten times maximum levels presently measured in any urban area. There is no evidence from animal toxicologic studies, controlled human exposures or epidemiologic observations that SO 2 at prevailing levels, or at levels two or three
times those presently permitted, pose any threat to human health. 3
Nevertheless, millions of dollars have been spent to reduce ambient
levels of what virtually all scientists knowledgeable in this field
now agree is an innocuous compound in the concentrations in which
it is presently found in the air of our cities.
New Source Performance Standards mandated by the Environmental Protection Agency (EPA) will require an estimated expenditure of at least $200 billion between now and the end of the century
to further control SO 2 emissions from coal combustion 4 No one
has been able to demonstrate that any comparable improvement
in the public health will result from this enormous expenditure
which will be borne by the general public through rising utility bills.
The experience of New York City in this respect has been instructive. In 1965 the New York City government decided to reduce
ambient SO 2 levels by limiting the sulfur content of oil burned in
the city to 1 percent. At considerable cost this was accomplished by
paying premium prices for low sulfur coal and desulfured oil. In
1970 even stricter standards were mandated by the federal government which made it necessary to limit the maximum concentration
of sulfur in New York City fuels to 0.3 percent. It is estimated that
this represented an additional cost to New York City's citizens of
$200 million per year at 1970 oil prices. Such an expenditure certainly could be justified if some concomitant improvement in health
could be demonstrated as a result.
The traditional measure of premature mortality which had been
used for many years in association with acute air pollution episodes
was applied to the New York City population for this time period by
Schimmel and his colleagues. By exhaustive statistical analysis, no
impact whatever could be demonstrated on total death rates in
New York City as a result of the lowered ambient SO 2 levels. 5
When deaths from respiratory, heart, circulatory diseases, and
cancer as a group (diseases which might most logically be associated with air pollution) were compared with SO 2 levels, again no
64
correlation could be demonstrated. Interestingly enough, the lack of
any correlation between S02 levels and daily mortality in the 1970s
could also be demonstrated in the 1960s before sulfur content of
fuel oil was restricted.
Acid Sulfates
As the innocuous nature of SO 2 at prevailing ambient levels has
become widely accepted by the scientific community, those attempting to incriminate sulfur emissions as hazardous to human
health have focused their attention on the more highly oxidized
states of sulfur and particularly sulfates. With restriction of sulfur
content of fuels, ambient air concentration of sulfates also showed
a marked decline, although not as great as SO 2 . As early as 1957,
Dr. Mary Amdur demonstrated a wide range of irritant potency of
sulfates in a sensitive guinea pig model.6 Sulfuric acid (H 2SO4) was
found, not surprisingly, to be the most irritating of the sulfate
species.
Ranking below sulfuric acid were sulfates with various metallic
cations of which the transition metals prove to be the most irritating. Irritant potency descended rapidly to an extremely low
level with ammonium sulfate and other less reactive cations. Ammonium sulfate proved to have less than one tenth of the irritant
potency of sulfuric acid.
These animal toxicology studies become of tremendous importance when translated to the real world since the vast majority of
sulfate (>90 percent) in ambient air is in the form of the innocuous
ammonium sulfate ((NH4)2SO4). Exposure of both healthy and asthmatic volunteers for two hours in controlled environmental exposure
chambers has failed to elicit any demonstrable effect on health by
exposure to (NH4)2SO 4 at levels 10 times those reached in the most
polluted cities.7 A small fraction of sulfate (-3-5 percent) is present
as H2 SO 4. Even this fraction, however, would appear to have little
significance for human health since recent human experimental
work has demonstrated ammonia production in the secretions of the
upper respiratory tract is more than sufficient to neutralize any
sulfuric acid which may be inhaled before it can reach the lung. 8
Ammonium sulfate and, to a much less extent sulfuric acid, comprise the vast amount of sulfates present in ambient air. Typically,
less than 5 percent of sulfates are found with a metallic cation.
Although most transition metals are found in most coals, they are
present only in minute amounts. The sources of these metals in
ambient air are therefore more likely to arise from industrial processes other than coal combustion, or as effluents from various
human activities.
Antedating the fall in SO2 levels in New York City air has been
a marked decrease in particulates. As in London, this decrease long
65
preceded our Clean Air Act. This steady decrease can be attributed
to many factors: among them a substantial change from coal to oil
and gas for home heating and power generation; phasing out of
individual apartment house incinerators; and improved control
technology for particulate emissions.
The introduction of electrostatic precipitators and other control
technology ensures that a return to coal for power generation will
not result in the heavy particulate loadings of 40 years ago. Unlike
SO2, fine particulate levels in ambient air appear to show a small
correlation with several measures of health effects, but the specific
compounds responsible for any of these effects remain to be identified. Study should be directed to whether there may be greater
health benefit in removing fine particulate matter (which includes
sulfates) from fossil fuel flue gases with a baghouse or other fabric
filter, than could be expected from wet scrubbing of effluents to
remove SO2 as proposed by EPA.
Since some of the sulfate and nitrate compounds present in fine
particulates have been shown to be innocuous in human-controlled
studies at levels well above present ambient levels in our most polluted cities, 9 increased attention is being directed to the metallic
cation associated with the sulfate or nitrate. Since most of the
transition metals are highly reactive and readily enter into biologic
reactions, their role in disease causation needs to be assessed further.
Oxides of Nitrogen
In addition to the sulfur oxide-particulate complex, another class
of pollutants produced in fossil fuel combustion are the oxides
of nitrogen. Of these, nitrogen dioxide (NO2 ) carries the greatest
potential for adverse effects on human health. Only half of ambient
air NO 2 can be ascribed to stationary sources since the automobile
is also a major contributor. Oxides of nitrogen produced whenever
any substances burn at high temperatures in air can be controlled
to a large extent by altering combustion conditions. Virtually all
of the oxides of nitrogen derive from the elemental nitrogen present
in air, rather than from the nitrates present in coal. They would be,
therefore, formed in any combustion process regardless of what substance is burned to provide energy.
In any case a wider margin of safety exists between ambient
air levels of NO 2 and levels at which toxic effects may appear than
for any other regulated air pollutant. Since some oxides of nitrogen
will end up as nitrates, pulmonary studies are being carried out to
determine the possible effects of these compounds on human health.
Initial studies indicate that as with sulfates, ammonium nitrate, the
commonest species formed, is also innocuous to human health. 9
Further studies using various metallic cations are presently being
carried out.
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From the above evidence, it can be deduced that SO2 at prevailing
ambient air levels is an innocuous substance with no implications for
human health. It can also be deduced that sulfate in ambient air also
carries no significant implication for human health. In fact, of all
components of fossil fuel combustion only fine particulate matter
(particle sizes below 10 um) appear to have even a slight correlation
with adverse health effects. Since particulate emissions can be controlled by appropriate techniques, it follows that even a doubling of
our present combustion of coal would produce no detectable adverse
human health effects. I am confident that none of the statistical
indices by which we customarily measure human health would show
any significant perturbation should our use of coal be doubled or
even tripled when burned with appropriate control technology.
In any case, numerous studies by many investigators have repeatedly shown air pollution to be a far smaller contributor to disease causation than weather, socio-economic and demographic
factors, occupational exposures, and personal health habits. All
of these overshadow community air pollution by at least an order
of magnitude in association with disease or death in man.
Some investigators have claimed that hidden within the nearly
two million deaths occurring yearly in the United States are more
than 100,000 premature deaths which can be related to fossil fuel
combustion products - particularly sulfates. 1 0 These figures are
obtained by taking death rates for Standard Metropolitan Statistical
Areas (SMSA) and regressing them against a series of socio-economic
and demographic factors for each area and against two measures
of air pollution. Using this technique they have claimed to find a
positive relationship between air pollution levels and numbers of
deaths. However, the data base from which these conclusions are
drawn is severely flawed." Furthermore, the same technique can be
used to show that socio-economic factors alone can account for all
of the variance in mortality between different SMSA.
In turning to coal to supply an increased portion of our energy
needs, we can do so with confidence that usage of appropriate control technology will prevent any significant adverse effect on the
health of our population. However, because of the costs of pollution
control, be they fuel cleaning, use of lower sulfur fuels, or control
of gas effluents, we must be certain that our controls are effectively
reducing those components of pollution that may be related to
adverse health effects. We should guard against the expenditure of
large sums of money to remove components of stack gas effluents
which may be of no significance to human health.
Using these criteria the expenditure of billions of dollars to
remove sulfur oxides is difficult to justify. Also, from a health
standpoint, removal of large particulates which have no relation
to human health or functioning is similarly difficult to justify.
67
Control of small particulates in the respirable range, however, may
well be an appropriate step to take.
This discussion is concerned only with possible adverse effects on
human health of fossil fuel combustion products. Other effects such
as possible acid deposition or reduction in visibility may be related
to some of the pollutants discussed. Whether society wishes to pay
the costs of removal of specific pollutants for benefits in these areas
is a societal judgment. If the answer be "yes", we should admit that
it is for one of these reasons that we are interested in control technology. Unless adverse effects on human health can be clearly
demonstrated by pollutants at present ambient levels, human health
should not be cited as the rationale for their control.
One additional important factor relating to electric power generation should also be considered in any assessment of health costs of
power generation. This is the impact on health from a shortage of
electricity due to reduced power generation, or to substantial increases in the cost of electricity and in the cost of fuel for home
heating due to attempts to further lower SO 2 levels in stack emission
either by installing expensive control technology, or by mandating
expensive low sulfur fuel. Directly observable health effects may
be anticipated from such actions.
Episodes of excess mortality such as those occasionally observed
with the acute air pollution episodes of past decades are now only
seen in two instances: influenza epidemics and heat waves. The
impact of an influenza epidemic on a community is customarily
measured by excess deaths reported from pneumonia and influenza.1 2
Such epidemics, in spite of immunization programs and antibiotics,
occur with deadly regularity every few years and take a toll of tens
of thousands on each occasion.
If higher electricity or fuel costs result in inadequate heating as
is often the case for the aged and poor in our cities, pneumonia
rates and deaths will predictably rise.
The only other dramatic perturbation in daily death rates is the
instantaneous tripling, or more, of deaths accompanying a heat
wave. 13 An abrubt rise in temperature in summer in major cities
has been repeatedly shown to be associated with an immediate rise
in deaths, largely among the already ill and the elderly. In recent
years as air conditioning has become more widely spread in nursing
homes and hospitals such peaks have largely disappeared. A significant increase in electricity costs, however, could force some such
institutions to curtail this amenity and an immediate rise in deaths
during heat waves would be the result.
Less dramatic, but equally real health costs which can be anticipated with more expensive electricity and more costly fuels are
deaths from hypothermia, and deaths associated with attempts at
supplemental heating such as burns and carbon monoxide poisoning.
68
Each year many thousands of elderly persons living in inadequately
heated homes are found dead. Although their deaths are usually
listed as due to heart attack, stroke or arteriosclerosis, careful investigation has demonstrated that many are actually due to hypothermia from inadequate heating.14
Each winter fires also take a toll of small children in poorly heated
buildings when attempts are made to supplement heating with
kerosene stoves or other dangerous substitutes. A further toll is
also exacted by deaths from carbon monoxide poisoning when
supplemental home heaters are inadequately ventilated.
All these health costs are real and must be balanced against any
anticipated benefit from reduced SO 2 levels achieved by costly
scrubbing of stack effluents, or by burning of expensive desulfured
fuel. Since no detectable excess mortality can be found ascribable
to SO 2 or sulfates at presently prevailing levels, money used to
reduce these levels still further might be better used for other public
health purposes.
Ecology
The effect of coal burning on ecosystems is a concern for three
reasons: (1) the operation of cooling systems may affect quatic
biota; (2) terrestrial flora may be affected if ground water becomes
contaminated by drainage from ash-disposal areas; and (3) acid
precipitation may be harmful to ecosystems.
Acid precipitation is probably the one greatest concern at present.
People are concerned about acid precipitation because the burning
of coal adds sulfur and nitrogen oxides to the atmosphere. These
oxides, by some physico-chemical process, are incorporated into
water drops which then become acidic and later cause acid precipitation. The acidic precipitation may then affect plant growth and
acidify surface water, thereby increasing mortality of aquatic species.
Increasing acidity has been reported in lakes in the Adirondack
Mountains of New York State and fish kills have also been reported
from that area.
Before coal combustion can be cited as causing the deleterious
effects, however, a certain sequence of events should be documented.
Firstly, we must show that the lake acidity killed the fish; secondly,
that the rainfall caused the lake acidity; thirdly, that power plant
emissions are responsible for acid rain. In some parts of the world,
we know that fish kills have occurred 12 but we do not know the
mechanism by which the mortality was increased, even if we can
document that acid rain in itself caused the lake to become acidic.
Finally, we have no idea how acid rain is actually formed, hence
we cannot identify the role of coal burning in its formation.
Extensive research is underway over the North Sea to study the
in-cloud processes that cause acid rain to form. A major effort is
69
also in progress to study causes of lake acidity in the Adirondacks a challenging area of study because of the proximity of three lakes
to each other, each lake having different pH values yet each receiving nearly identical rainfall.
Some claims have been made that rainfall over the past 20 years
has been getting more acidic in the eastern U.S. and that the area
receiving acid rain is getting larger. A careful examination of the data
in the published papers, however, shows that such conclusion cannot
be fully supported. Before one can postulate changes for different
time periods, one must compare the nature of rainfall at identical
stations. If data only from identical stations are compared, no trend
in changing acidity of rainfall can be discerned. We know that acid
rain falls but we cannot quantify damage to ecosystems nor do we
understand the mechanism by which such rain is formed. As a
result, we cannot assess the impact of coal burning in causing acid
precipitation, hence we cannot evaluate what role the increased use
of coal will play.
The concern over damage to aquatic biota from cooling operations is real; however, again the net effect of power plant operation
cannot yet be specified. The complexity of population dynamics
makes any net assessment difficult until more research on the subject is completed. Similarly, the effect of waste disposal on ground
water chemistry and then on terrestrial ecosystems is very poorly
understood. We do not yet understand the physico-chemical nature
of solid waste (ash and sludge), hence we cannot predict what toxic
components will be leached. Nor can we calculate sorption by soil
or plant uptake from soil of many trace metals. Again, we face a
complex problem with many facets, few of which are quantitatively
understood.
Visibility Degradation
Atmospheric sulfate occur in a size range that can scatter light
enough to impair visibility. But again, the quantitative relations
are lacking. A number of correlations between visibility and ambient
sulfate levels have been reported. Trijonas1 5, for example, related
sulfate concentrations to visibility at airports. Such correlative relations have two problems. Firstly, the visibility values themselves
have a large uncertainty; secondly, the sulfate values are based on
early measurement techniques which we now know tended to result
in more sulfate being reported than actually was present (because of
sulfate formation from SO 2 on the collecting device). Admittedly,
it has been observed that visibility increased in the Southwest during a
smelter strike when no SO2 was being emitted, but increased visibility has also occurred when the smelters were operating.
The visibility question centers around quantification and our
ability to relate degradation to coal burning. Admittedly, sulfate
70
will affect visibility but a quantitative relationship in the real world
is still wanting. More obscure is the quantitative relation between
atmospheric sulfates and their emitted precursor, SO 2 and ambient
concentration of sulfate, hence we cannot assess how sulfate levels
will change as a function of SO 2 emissions.
Many examples can be cited of reduction in SO 2 concentration
but no concomitant reduction in sulfate level. The sulfate concentration in the atmosphere apparently depends on a number of
factors, among which meteorological conditions are very important.
As a result, even though we can calculate the effect of increased
coal burning on SO 2 emissions, we cannot know what effect those
emissions will have on sulfate concentrations, hence on visibility
degradation.
Climatic Change
Over the past 2 to 3 years, a noticeable interest in CO 2 emissions
(and in atmospheric CO 2 levels) has developed. The interest centers
around the concern that high CO 2 levels in the troposphere would
block thermal radiation from the earth's surface, thereby increasing
surface temperatures. Such temperature increases could cause major
global climatic perturbations.1 6 Many climatologists feel that a 1 to
2 degree rise in temperature might not be serious. A 4 to 5 degree
rise, however, could be disastrous.
An important need is to establish what temperature changes
might occur if we continue burning fossil fuels at an increasing
rate. Unfortunately, making such a prognostication is fraught with
many uncertainties. We know (from limited but high-quality observations) that atmospheric CO 2 concentrations have increased from
about 315 ppm to about 335 ppm over the past 20 years.1 6 And
that increase can be accounted for if one allows half the CO2 from
fuel burning to stay in the atmosphere. Based on the observed
increase, many scientists have projected a doubling of the preindustrial CO 2 level by about the middle of the 21st century. Such
a doubling could then cause an increase in global temperatures.
It should be obvious that any future temperature prediction is
based on a number of contributing factors, each of which has an
uncertainty. To make a prediction on temperature increases or
climatic disturbance, we must first know energy demand over the
next 50 to 100 years, as well as the fuel mix which satisfies that
demand. And the demand, of course, is based on projected growth
rates.
Knowing demand and fuel use, we should be able to predict CO 2
levels, assuming a particular global CO2 cycle. Using such an approach, the doubling of the pre-industrial CO2 level is estimated
to occur between 2020 and 2090.16 1
17, 18
Taking into consideration
the different uncertainties, Laurmann 1 9 has tried to approach the
71
problem from a probability viewpoint. For example, for a 3 percent
growth rate, the temperature rise in 2040 would be 2.5 degrees,
with a standard deviation of about 100 percent. The likelihood of
a 5 degree rise by 2040 is perhaps 20 percent. As great as these
uncertainties are, they still assume a linear relation between CO2
concentration and CO 2 production from fossil-fuel burning, i.e.,
approximately half the CO2 produced by combustion remains in the
atmosphere.
Without pressing the issue further, we can recognize a number of
uncertainties: (1) the projected energy demand, (2) the mix of fuels
needed to satisfy that demand, (3) the relation between CO 2 output
and atmospheric concentrations, (4) the temperature rise resulting
from an increase in CO 2 levels, and (5) the effect of a given temperature change on climate. Point 3 involves the overall global carbon
cycle - a cycle for which much research is needed, especially the
oceanic/atmosphere exchange, before meaningful projections can be
made. Point 5 is also critical. Perhaps one of the weakest links in our
ability to predict climatic perturbations is the uncertainty in existing
climatic models.
Certainly, fossil-fuel burning will result in changes in atmospheric
CO2 concentrations but, with the present uncertainties in our knowledge, we cannot judge what the changes will be, what they will do to
climate, or what the effect on society will be. By the year 2000,
we do not anticipate drastic effects of increased CO 2 concentrations;
however, the question of climatic change cannot be ignored. Further,
the entire CO 2 question is a global, not national, problem.
Conclusions
The use of coal will almost certainly increase over the next 20
years, and that use will have an effect on the environment. At our
present state of knowledge, however, we cannot quantify many of
the anticipated effects. At best, we can identify potential hazards
to the physical and biological environment and we can carry out a
continuing research program to assess that potential in order to take
corrective actions where needed. Such a research effort is actively
underway by both industry and governmental groups. Hopefully,
that research will provide the data needed to insure the environmental acceptability of increased coal use.
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Frank, N. R., M. 0. Amdur, J. Worcester, and J. L. Whittenberger, "Effect of acute
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