Fundamentals of Air Pollution

929 Pages·2007·19.238 MB·English

by  Daniel A. Vallero (Auth.)

Preface to the
Third Edition
The authors of this book include a chemist (Donald .L Fox), a meteorolo-
gist (D. Bruce Turner), and a mechanical engineer (Richard .W Boubel). This
1:1:1 ratio has some relevance in that it approximates the ratio of those pro-
fessionally involved in the field of air pollution. In the environmental protec-
tion and management field, the experience of the recent past has been that
physicists and electrical engineers have been most attracted to the radiation,
nuclear, and noise areas; biologists and civil engineers to the aquatic and
solid waste areas; chemists, meteorologists, and chemical and mechanical
engineers to the area of air pollution and its control. These remarks are not
intended to exclude all others from the party (or from this course). The con-
trol of air pollution requires the combined efforts of all the professions men-
tioned, in addition to the input of physicians, lawyers, and social scientists.
However, the professional mix of the authors, and their expectation of a
not-too-dissimilar mix of students using this book, forewarns the tenor of its
contents and presentation.
Although this book consists of six parts and three authors, it is not to be con-
sidered six short books put together back-to-back to make one large one. By
and large, the several parts are the work of more than one author. Obviously,
the meteorologist member of the author team is principally responsible for the
part of the book concerned with the meteorology of air pollution, the chemist
author for the chapters on chemistry, and the engineer author for those on
engineering. However, as you will see, no chapters are signed, and all authors
xvii
xviii Preface to the Third Edition
accept responsibility for the strengths and weaknesses of the chapters and for
the book as a whole.
In the 20 years since publication of the first edition of Fundamentals of Air
Pollution (1973), and the 9 years since the second edition (1984), the fundamen-
tals have not changed. The basic physics, chemistry, and engineering are still
the same, but there is now a greater in-depth understanding of their applica-
tion to air pollution. This edition has been edited, revised, and updated to
include the new technology available to air pollution practitioners. Its contents
are also influenced to a great extent by the passage of the US Clean Air Act
Amendments of 1990 (CAAA90). These amendments have changed the health
and risk-based regulations of the US Clean Air Act to technology-driven regu-
lations with extensive penalty provisions for noncompliance.
We have added more detailed discussion of areas that have been under
intensive study during the past decade. There has been a similar need to add
discussion of CAAA90 and its regulatory concepts, such as control of air tox-
ics, indoor air pollution, pollution prevention, and trading and banking of
emission rights. Ten more years of new data on air quality have required the
updating of the tables and figures presenting these data.
We have expanded some subject areas, which previously were of concern to
only a few scientists, but which have been popularized by the media to the point
where they are common discussion subjects. These include "Global Warming,"
"The Ozone Hole, .... Energy Conservation, .... Renewable Resources," and
"Quality of Life."
With each passing decade, more and more pollution sources of earlier
decades become obsolete and are replaced by processes and equipment that
produce less pollution. At the same time, population and the demand for
products and services increase. Students must keep these concepts in mind
as they study from this text, knowing that the world in which they will prac-
tice their profession will be different from the world today.
The viewpoint of this book is first that most of the students who elect to
receive some training in air pollution will have previously taken courses in
chemistry at the high school or university level, and that those few who have
not would be well advised to defer the study of air pollution until they catch
up on their chemistry.
The second point of view is that the engineering design of control systems for
stationary and mobile sources requires a command of the principles of chemical
and mechanical engineering beyond that which can be included in a one-vol-
ume textbook on air pollution. Before venturing into the field of engineering
control of air pollution, a student should, as a minimum, master courses in
internal combustion engines, power plant engineering, the unit processes of
chemical engineering, engineering thermodynamics, and kinetics. However,
this does not have to be accomplished before taking a course based on this
book but can well be done simultaneously with or after doing so.
The third point of view is that no one, regardless of their professional back-
ground, should be in the field of air pollution control unless they sufficiently
Preface to the Third Edition xix
understand the behavior of the atmosphere, which is the feature that differ-
entiates air pollution from the other aspects of environmental protection and
management. This requires a knowledge of some basic atmospheric chem-
istry in addition to some rather specialized air pollution meteorology. The
viewpoint presented in the textbook is that very few students using it will
have previously studied basic meteorology. It is hoped that exposure to air
pollution meteorology at this stage will excite a handful of students to delve
deeper into the subject. Therefore, a relatively large proportion of this book
has been devoted to meteorology because of its projected importance to the
student.
The authors have tried to maintain a universal point of view so that the
material presented would be equally applicable in all the countries of the
world. Although a deliberate attempt has been made to keep American
provincialism out of the book, it has inevitably crept in through the exclusive
use of English language references and suggested reading lists, and the pre-
ponderant use of American data for the examples, tables, and figures. The
saving grace in this respect is that the principles of chemistry, meteorology,
and engineering are universal.
As persons who have dedicated all or significant parts of their profes-
sional careers to the field of air pollution, the authors believe in its impor-
tance and relevance. We believe that as the world's population increases, it
will become increasingly important to have an adequate number of well-
trained professions engaged in air pollution control. If we did not believe
this, it would have been pointless for us to have written this textbook.
We recognize that, in terms of short-term urgency, many nations and com-
munities may rightly assign a lower priority to air pollution control than to
problems of population, poverty, nutrition, housing, education, water sup-
ply, communicable disease control, civil rights, mental health, aging, or
crime. Air pollution control is more likely to have a higher priority for a per-
son or a community already reaping the benefits of society in the form of
adequate income, food, housing, education, and health care than for persons
who have not and may never reap these benefits.
However, in terms of long-term needs, nations and communities can
ignore air pollution control only at their peril. A population can subsist, albeit
poorly, with inadequate housing, schools, police, and care of the ill, insane,
and aged; it can also subsist with a primitive water supply. The ultimate
determinants for survival are its food and air supplies. Conversely, even
were society to succeed in providing in a completely adequate manner all of
its other needs, it would be of no avail if the result were an atmosphere so
befouled as not to sustain life. The long-term objective of air pollution con-
trol is to allow the world's population to meet all its needs for energy, goods,
and services without sullying its air supply.
Preface to the
Fourth Edition
In the Preface to the Third Edition of this book, Donald .L Fox, D. Bruce
Turner, and Richard .W Boubel expressed the importance of a multidiscipli-
nary approach to air pollution. I wholeheartedly agree. Nothing has
changed in this regard, making it a daunting challenge to update the impres-
sive work of these renowned experts (as well as the late Arthur C. Stern in
previous editions). It was easier to add new material than to remove old
material. A new edition is an optimization exercise. The book must not
change so much that professors using it have to change the course structure
so severely that it constitutes a completely new text. On the other hand, a
text must be up to date in terms of current technologies and programs, as
well as in addressing threats on the horizon.
Over a decade has passed since the publication of previous version. From a
regulatory perspective, this is a very long time. By conventional measures, such
as the National Ambient Air Quality Standards, the past decade has been very
successful. But, science marches on. I recall that in the 1970s, detection in the
parts per million (ppm) was impossible for most compounds. During the 1980s
detection limits continued to decrease. Now, detections have improved to allow
for measurements below parts per billion for many compounds. We have also
witnessed sea changes in risk assessment and management. For example, the
US Environmental Protection Agency laboratories were realigned to address
risks, with separate laboratories to conduct research exposure, effects, risk char-
acterization, and risk reduction.
xxi
xxii Preface to the Fourth Edition
Indeed, the previous authors were quite prescient in predicting the effects
of the then newly amended Clean Air Act. The major changes started to kick
in as the focus moved from technology-based approaches (best available and
maximum achievable control technologies) to risk-based decision-making
(residual risks remaining even after the required control technologies).
The fundamentals of the science underlying air pollution have not changed,
but their applications and the appreciation of their impacts have. For example,
I have endeavored to enhance the discussion and explanation of the physical
and chemical processes at work, particularly those related to air toxics. This
has been a tendency through all four editions. New technologies must be
explained, better models and computational methods have become available,
analytical procedures have evolved and improved, and acute and chronic
effects have become better understood. All of these have enhanced the science
and engineering knowledge available to practitioners, teachers, and students.
And, the savvy of the lay public about air pollution has grown substantially
during the previous decade.
I am indebted to my fellow scientists and engineers for their insights and
comments on how to incorporate the new trends. I particularly want to note
Alan Huber, who shared his work in atmospheric dispersion modeling,
especially computational fluid dynamics. Others include Russ Bullock (mer-
cury fate and transport), Paul Lioy and Panos Georgopoulos (modeling),
Mark Wiesner (nanotechnology), John Kominsky and Mike Beard (asbestos),
and Aarne Vesilind (history).
As in previous editions, my expectation is that the reader has received
some formal background in chemistry. I agree with the previous authors that
anyone interested in air pollution must have a solid grounding in chemistry
and the physical sciences. Without it, there is no way of knowing whether
a rule or policy is plausible. I have seen too many instances of "junk science"
in environmental decision-making. Often, these are underlain with good
intentions. But, so-called "advocacy" does not obviate the need for sound sci-
ence. That said, with a bit of effort, much of this edition can be a useful tool
to any audience who is motivated to understand the what, how and why of
air pollution.
Another trend that I have hoped to capture is the comprehensiveness
needed to address air quality. A problem need not occur if the processes
leading to air pollution are approached from a life cycle or "green" perspec-
tive. This goes beyond pollution prevention and calls for an integrated and
sustainable view. I have dedicated an entire chapter to this emergent envi-
ronmental expectation.
The authors of the previous edition introduced discussions about some
emerging continental and global threats to the atmosphere. Since then,
the urgency of some has abated (e.g. acid rain and some threats to the ozone
layer), some have increased in concern (e.g. global warming), and others
have continued but the contaminants of concern have varied (long-range
transport of persistent chemicals). The scientific credibility of arguments
Preface to the Fourth Edition xxiii
for and against regulatory and other actions has been uneven. The best
defense against bad policy decisions is a strong foundation in the physical
sciences.
Let me rephrase that a bit more proactively and optimistically:
My overall objective of this book is to give you, the reader, the
ability to design and apply the tools needed to improve and sustain
the quality of the air we breathe for many decades. These tools can
only be trusted if they are thoroughly grounded in the Fundamentals
of Air Pollution.
DAV
1
ehT hanging.Face
of ir Pollutzon
I. DEFINING AIR POLLUTION
Air pollution: The presence of contaminants or pollutant substances in the air that
interfere with human health or welfare, or produce other harmful environmental
effects.
United States Environmental Protection Agency (2007)
"Terms of Environment: Glossary, Abbreviations and Acronyms"
The US Environmental Protection Agency's (EPA) definition is a good place
to start thinking about what makes something an air pollutant. The key verb
in the definition is "interfere." Thus, we obviously have a desired state, but
these substances are keeping us from achieving that state. So, then, what is
that state? The second part of the definition provides some clues; namely, air
must be of a certain quality to support human and other life.
Some decades ago, few people were familiar with the term pollution. Of
course, most people knew that something was amiss when their air was
filled with smoke or when they smell an unpleasant odor. But, for most pol-
lutants, those that were not readily sensed, a baseline had to be set to begin
to take action. Environmental professionals had to reach agreement on what
4 1. The Changing Face of Air Pollution
is and what is not "pollution." We now have the opposite problem, nearly
everyone has heard about pollution and many may have their own working
definitions. So, once again, we have to try to reach consensus on what the
word actually means.
Another way to look at the interferences mentioned in the EPA definition
is to put them in the context of "harm." The objects of the harm have received
varying levels of interests. In the 1960s, harm to ecosystems, including
threats to the very survival of certain biological species was paramount. This
concern was coupled with harm to humans, especially in terms of diseases
directly associated with obvious episodes, such as respiratory diseases and
even death associated with combinations of weather and pollutant releases.
Other emerging concerns were also becoming apparent, including anxiety
about nuclear power plants, particularly the possibilities of meltdown and the
generation of cancer-causing nuclear wastes, petrochemical concerns, such as
the increasing production and release of ominous-sounding chemicals like
Dichloro-Diphenyl-Trichloroethane (DDT) and other pesticides, as well as
spills of oil and other chemicals. These apprehensions would increase in the
next decade, with the public's growing wariness about "toxic" chemicals
added to the more familiar "conventional" pollutants like soot, carbon monox-
ide, and oxides of nitrogen and sulfur. The major new concern about toxics
was cancer. The next decades kept these concerns, but added new ones,
including threats to hormonal systems in humans and wildlife, neurotoxicity
(especially in children), and immune system disorders.
Growing numbers of studies in the last quarter of the twentieth century pro-
vided evidence linking disease and adverse effects to extremely low levels of
certain particularly toxic substances. For example, exposure to dioxin at
almost any level above what science could detect could be associated with
numerous adverse effects in humans. During this time, other objects of pollu-
tion were identified, including loss of aquatic diversity in lakes due to deposi-
tion of acid rain. Acid deposition was also being associated with the corrosion
of materials, including some of the most important human-made structures,
such as the pyramids in Egypt and monuments to democracy in Washington,
DC. Somewhat later, global pollutants became the source of public concern,
such as those that seemed to be destroying the stratospheric ozone layer or
those that appeared to be affecting the global climate.
This escalation of awareness of the multitude of pollutants complicated
matters. For example, many pollutants under other circumstances would be
"resources," such as compounds of nitrogen. In the air, these compounds can
cause respiratory problems directly or, in combination with hydrocarbons
and sunlight indirectly can form ozone and smog. But, in the soil, nitrogen
compounds are essential nutrients. So, it is not simply a matter of "removing"
pollutants, but one of managing systems to ensure that optimal conditions
for health and environmental quality exist. When does something in our
air change from being harmless or even beneficial to become harmful?
Impurities are common, but in excessive quantities and in the wrong places
I. Defining Air Pollution 5
they become harmful. One of the most interesting definitional quandaries
about pollution has come out of the water pollution literature, especially by
the language in the Federal Water Pollution Control Act Amendments of
1972 (Public Law 92-500). The objective of this law is to restore and maintain
the chemical, physical, and biological integrity of the nation's waters. To
achieve this objective, the law set two goals: the elimination of the discharge
of all pollutants into the navigable waters of the United States by 1985; and
to provide an interim level of water quality to protect fish, shellfish, and
wildlife and recreation by 1983.1 Was Congress serious? Could they really
mean that they had expected all sources that drained into US lakes and
rivers to be completely free of pollutants in 31 years? Or did this goal hinge
upon the definition of pollutant? In other words, even toxic substances are
not necessarily "pollutants" if they exist below a threshold of harm. In light
of the fact that this same law established so-called "effluent limitations,"
there is a strong likelihood that the definition called for in this goal was
concentration-based. 2
This paradigm spilled over into air pollution circles. More recently, the term
"zero emission" has been applied to vehicles, as the logical next step follow-
ing low emission vehicles (LEVs) and ultra-low emission vehicles (ULEVs) in
recent years. However, zero emissions of pollutants will not be likely for the
foreseeable future, especially if one considers that even electric cars are not
emission free, but actually emission trading, since the electricity is generated at
a power plant that is emitting pollutants as it bums fossil fuels or has the prob-
lem of radioactive wastes if it is a nuclear power plant. Even hydrogen, solar
and wind systems are not completely pollution free since the parts and
assemblages require energy and materials that may even include hazardous
substances.
These definitional uncertainties beg the question, then, of when does an
impurity become a pollutant? Renaissance thinking may help us here.
Paracelsus, the sixteenth century scientist is famous for his contention that
"dose alone makes a poison .... All substances are poisons; there is none
133 USC 1251.
2 In fact, my own environmental career began shortly after the passage of this law, when it,
along with the National Environmental Policy Act and the Clean Air Act of 1970, was establish-
ing a new environmental policy benchmark for the United States. At the time environmentalists
recited an axiom frequently: "Dilution is not the solution to pollution!" I recall using it on a reg-
ular basis myself. However, looking back over those three decades, it seems the adage was not
completely true. Cleanup levels and other thresholds are concentration based, so if one does an
adequate job in diluting the concentrations (e.g. dioxin concentrations below I part per billion,
ppb), one has at least in part solved that particular pollution problem. Also, when it came to
metal pollution, dilution was a preferred solution, since a metal is an element and cannot be
destroyed. A sufficient amount of the metal wastes are removed from water or soil and moved
to a permanent storage site. The only other engineering solution to metal pollution was to
change its oxidation state and chemical species, which is not often preferable because when
environmental conditions change, so often do the oxidation states of the metals, allowing them
to again become toxic and bioavailable.
6 1. The Changing Face of Air Pollution
which is not a poison. The right dose differentiates a poison and a remedy. ''3
Paracelsus' quote illuminates a number of physical, chemical, and biological
concepts important to understanding air pollution. Let us consider two.
First, the poisonous nature, i.e. the toxicology, of a substance must be related
to the circumstances of exposure. In other words, to understand a pollutant,
one must appreciate its context. Air pollutants become a problem when they
come into contact with the receptor. This leads to some important questions
that must be answered if we are to address air pollution:
.1 What is the physical, chemical, and biological nature of the agent to which
the receptor (e.g. a person, an endangered species, or an entire population
or ecosystem) is exposed?
.2 What is that person's existing health status?
.3 What is the condition of the ecosystem?
4. What are the chemical composition and physical form of the contaminant?
.5 Is the agent part of a mixture, or is it a pure substance?
.6 How was the person or organism exposed; from food, drink, air, through
the skin?
These and other characterizations of a contaminant must be known to
determine the extent and degree of harm.
The second concept highlighted by Paracelsus is that dose is related to
response. This is what scientists refer to as a biological gradient or a dose-
response relationship. Under most conditions, the more poison to which one is
exposed the greater the harm.
The classification of harm is an expression of hazard, which is a component
of risk. The terms hazard and risk are frequently used interchangeably in
everyday parlance, but hazard is actually a component of risk. As we will see
throughout this text, hazard is not synonymous with risk. A hazard is
expressed as the potential of unacceptable outcome, while risk is the likeli-
hood (i.e. probability) that such an adverse outcome will occur. A hazard can
be expressed in numerous ways. For chemical or biological agents, the most
important hazard is the potential for disease or death (referred to in medical
literature as "morbidity" and "mortality," respectively). So, the hazards to
human health are referred to collectively in the medical and environmental
sciences as "toxicity." Toxicology is chiefly concerned with these health out-
comes and their potential causes.
To scientists and engineers, risk is a straightforward mathematical and
quantifiable concept. Risk equals the probability of some adverse outcome.
Any risk is a function of probability and consequence. 4 The consequence can
take many forms. In environmental sciences, a consequence is called a "hazard."
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