Unraveling Environmental Disasters

By Daniel A. Vallero and Trevor Letcher

Unraveling Environmental Disasters, Second Edition provides scientific explanations of the most threatening current and future environmental disasters, including an analysis of ways disasters could have been prevented and how to minimize risk of similar disasters in the future. In this new edition the authors provide foundational knowledge on why certain environmental disasters occur and ways of reducing the risk of recurrences. Anyone involved in teaching or working in the main sciences of physics, chemistry, and biology, or in the applied sciences, including engineering, design, planning, and homeland security, should read the book to become acquainted with these very important issues.

• Evaluates natural hazards and disasters with an emphasis on lessons learned for better future forecasting
• Considers the impact of human systems on environmental disasters, treating disasters as complex systems
• Provides detailed predictions, based upon sound science, on why disasters occur
• Includes fully updated chapters on food, health, and water
• Focuses on both theoretical and practical aspects of each disaster
• Includes disasters related to climate change and pollution

• Language: English
• Publisher: Elsevier Science
• Release date: Oct 17, 2023
• ISBN: 9780443186523

Daniel A. Vallero

Professor Daniel A. Vallero is an internationally recognized author and expert in environmental science and engineering. He has devoted decades to conducting research, teaching, and mentoring future scientists and engineers. He is currently developing tools and models to predict potential exposures to chemicals in consumer products. He is a full adjunct professor of civil and environmental engineering at Duke University’s Pratt School of Engineering. He has authored 20 environmental textbooks, with the most recent addressing the importance of physical principles in environmental science and engineering. His books have addressed all environmental compartments and media within the earth’s atmosphere, hydrosphere, lithosphere, and biosphere.

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Preface

Unfortunately, disasters have been plentiful since the first edition of this book. Several of the problems we discussed continued to occur, with some even worsening, such as loss of human life near coastal areas, leaks and spills, and threats to sensitive habitats. Some are quite recent and bewildering, such as the viral pandemic and the war in Ukraine. Even disasters like these that are predominantly public health and safety catastrophes have attendant negative impacts on the environment. As such, there are few disasters that, at least in part, are not environmental disasters. Sometimes, there are bronze linings, we will not go so far as to call them silver linings, during a disaster, such as an economic pullback or social unrest, that slightly improve the environment. For example, there were a few months in the recent past that saw air quality improve in association with lower economic activity stemmed by the pandemic [1]. However, these conditions have also harmed other parts of the environment, such as the substantial increase in surface and groundwater loading of domestic wastes from disposable gloves, masks, temporary protective equipment, and other biohazards during the pandemic [2].

The backgrounds of this book’s two authors indicate large diversity of terminology and ontology, even among similar scientific disciplines, regarding complex phenomena like disasters. Letcher is a thermodynamicist. As such, he is concerned about the first principles of physics, especially those related to the relationships between mass and energy within systems. Systems may range in scale from molecular to the universe. To Letcher, a disaster is merely the outcome of processes and mechanisms involving energy and substances. His explanation of a disaster is an exposition of events that led to an unpleasant outcome. The science that underpins these causal chains and the possible next steps can be explained and, hopefully, lead to scientifically sound steps that may reduce the likelihood of these outcomes in the future. The good news is that Letcher and his fellow physicists have improved understanding of these underpinning first principles of physics. The bad news is that all science is fraught with uncertainty and variability. Even a small error can lead to wrong and fateful decisions. And, although one scenario may be sufficiently explained, it will vary in profound and subtle ways from all other scenarios. Such variability is what keeps scientists awake at night.

Vallero’s expertise is engineering and, in particular, environmental engineering. As such, he is interested in applying those same principles of interest as Letcher, but within the context of the environment. Environments consist of both living and nonliving components, i.e., biotic and abiotic, respectively. Thus, like Letcher, he is concerned with thermodynamic systems, especially how energy flows, how it is transformed, and how the organisms are affected by such energy flows. Again, the first principles of physics must be understood and applied to environmental phenomena. However, the system ranges usually fall between the habitat of a microbe (e.g., bacterium or virus) and the planet (the effect of changes in the atmosphere on large ecosystems). As such, environmental scientists and engineers consider disasters to be collective outcomes of changes in these systems. This means the kinds of disasters that keep these folks up at night are those that are possible or even impending (e.g., some scientists fear biome shifts due to climate change leading to food crises).

All chapters from the first edition have been revised, some more so than others. For example, extensive new material has been added to the chapters on climate and unsustainability. Indeed, these updates and expansions try to take an honest view of the pros and cons of various contentious and polarizing issues. For example, we delve into the advantages of electric vehicles to decrease the world’s dependence on fossil fuels, but also assess the downsides, such as the greater extraction and processing of rare metals. Almost always, balances are needed in such complex problems.

Three new chapters have been added to the book. The introductory chapter entitled Disaster Characterization sets the stage for evidence-based risk assessments in forecasting and addressing environmental problems that can lead to disasters. Health disasters draw upon the lessons learned from environmentally related diseases, such as cancer and endocrine disruption, as well as the many lessons thrust upon the world from the recent pandemic. Climate is now addressed by expanding and extending the discussions, first to describe and characterize climate and how it changes both naturally and how human activities can affect and worsen the natural changes. This is followed by ways that the pending problems can be addressed and, hopefully, be avoided.

Thus, our approach is to be objective about disasters and, where we can, offer insights into the root causes and potential actions needed to prevent future repeats of conditions that led to them in the first place. We know that some of the topics we cover have too often been addressed by scientific experts, at the exclusion of the others. Our hope is to cover even the most complicated material so that the reader does not have to be an expert or even a scientist to understand. Granted, there may be subject matter that will require a few re-readings, but perhaps not too many. Even so, please be assured that even we experts know only a small fraction of what needs to be known. We tend to work in some highly specialized areas, so we also have to Google topics outside of our span of knowledge (and often within that domain) to understand others’ expertise. As evidence, look how many scientific expert reviewers, committee members, task force leads, and other scientists sit on the Intergovernmental Panel on Climate Change (visit: https://www.ipcc.ch/about/structure/). And that is just one, albeit very important, environmental problem. Be assured that we had to leave our comfort zones many times in writing the first edition and even more in this second one. But, like any time you add a few wrinkles to your gray matter [3], we expect your interest in this book will help you understand and teach others about the causes and actions to address environmental disasters.

Daniel A. Vallero, Duke University, Durham, NC, United States

Trevor M. Letcher, Emeritus ProfessorStratton-on-the-Fosse, United Kingdom, University of KwaZulu-Natal, Durban

References

[1] Rupani P.F., Nilashi M., Abumalloh R.A., Asadi S., Samad S., Wang S. Coronavirus pandemic (COVID-19) and its natural environmental impacts. Int J Environ Sci Technol. 2020;17(11):4655–4666.

[2] You S., Sonne C., Ok Y.S. COVID-19's unsustainable waste management. Science. 2020;368(6498):1438.

[3] Tallinen T., Chung J.Y., Biggins J.S., Mahadevan L. Gyrification from constrained cortical expansion. Proc Natl Acad Sci. 2014;111(35):12667–12672.

Chapter 1 Disaster characterization

Abstract

Basic physical and chemical characteristics of air pollutants are discussed in the context of environmental stressors as factors leading to or exacerbating disasters. Methods for calculating and expressing air pollutant concentrations are provided. The chapter also introduces the process that lead to the formation and transformation of substances that ultimately become air pollutants. Formation kinetics, the rate laws, and rate order are discussed, along with the various types of reactions involved in air pollutant formation and transformation. Non-chemical, especially biological, pollutants are also discussed.

Keywords

Hydrologic cycle; Risk assessment; Risk perception; Disaster taxonomy; Natural disaster; Anthropogenic disaster

The taxonomy of disasters

What is a disaster? More specifically, what is an environmental disaster? There is no consensus, scientific or otherwise, on the definition, but there are a few intuitive guidelines. It must be more severe than a regularly encountered problem. It is often something unexpected. Governments have quantitative and financial thresholds that determine whether an event or series of events constitute a disaster [1–3]. At the other end of the objective scale, journalists and news organizations often characterize a wide range of events as disasters [4]. These characterizations are often made notwithstanding any criteria or standards differentiating an environmental problem like a localized fish kill from an environmental disaster like a wetland-destroying drought.

An environmental disaster may exclusively be a human disaster, which is accompanied by loss of life, associated with out-of-the-ordinary injury and disease. This could be a so-called toxic cloud or other pollutant release. An environmental disaster may also be exclusively an ecological disaster, where sensitive habitats are harmed. Such habitats are not able to withstand the harm that is directly the result of pollutant exposure or indirect effects of pollution or natural events, such as a spill or extreme weather event, respectively. Even a seemingly mild event could trigger an ecological disaster if the ecosystem is not sufficiently resilient. That is to say, the system is not capable of recovering from the harm imposed by the event [5–7].

Sources of disaster

Often, the major question when characterizing an environmental disaster is the extent to which human activities played a role in the severity and frequency of certain disasters. Were the causes anthropogenic or natural. Indeed, there are few if any recent disasters that can be described as completely natural in origin. Pollution has reached even the most remote regions, detected near both the North [8–13] and South Poles [14–16].

Human activities may contribute factors to natural conditions so as to induce natural events to reach the disaster threshold. Recent examples include the completely natural occurrence of the earthquake in the Sea of Japan. This was entirely the result of Japan's tectonic situation. The main island, Honshu Island, is located where the Eurasian, Pacific, and Philippine Sea tectonic plates meet and push against each other, so a tsunami is a probable outcome. The expected tectonic factors were exacerbated by human decisions and actions, especially that of siting nuclear power plant within a such a tectonically active zone, as well as the lack of preparedness for cooling of fuel rods, poor evacuation protocols, and engineering and design failures [17].

The hydrologic cycle plays a substantial role in disasters. The obvious examples are meteorological events, such as hurricanes, tornados, and floods. However, the disasters are often a mix of atmospheric and terrestrial phenomena. For example, a levee or dam breach, such as the recent catastrophic failures in New Orleans during and in the wake of Hurricane Katrina, experienced failure when flow rates reached cubic meters per second. Conversely, a hazardous waste landfill failure may be reached when flow across a barrier exceeds a few cubic centimeters per decade.

Both of these disasters were determined by the loading of water into a system. In the case of the hurricane, the loading occurs rapidly over a period of a few days, whereas the loading of the landfill occurs over decades. Both systems were also affected by terrestrial phenomena, such as the water holding capacity of soils and subsurface materials. Once the ground becomes saturated, it runs overland, leading to pressure on levees and swelling streams. Thus the damage incurred from or worsened by precipitation and other hydrological factors have temporal dimensions. If the outcome (e.g., polluting a drinking water supply) occurs in a day, it may well be deemed a disaster, but it if the same level of pollution is reached in a decade, it may be deemed an environmental problem but not a disaster. Of course, if this is one's only water supply, as soon as the problem is uncovered, it becomes a disaster to that person. In fact, it could be deemed worse than a sudden-onset disaster, since one realizes he or she has been exposed by a long time. This was the case for some of the infamous toxic disasters of the 1970s, notably the Love Canal incident (see Chapter 7).

From a scientific perspective, a first step of studying disasters is to create a taxonomy. Classifying disasters by their causes and effects allows for the deconstruction of the events that led to the disaster and enhances the understanding needed to prevent and address future problems. Even a well-designed and implemented disaster analysis has large amounts of uncertainty and variability. A very small error or misinterpretation of a specific detail of an event in the causal chain can lead to large calculation errors and could misinform future decisions and actions [18,19]. There are many definitions of disaster. Scientists generally loathe ambiguity in trying to explain physical phenomena because the scientific method requires objectivity [20–22]. To do so, they need a common naming technique. This taxonomy is a first step in describing and then characterizing phenomena. The next step is ontology, that is, how do all of these phenomena relate to each other?

When preparing for the first edition of this book, we asked a number of engineering and science leaders to provide their operational definition of a disaster. The definitions had much in common but ranged in emphasis. Most agreed that disasters are low-probability events with high-value consequences. Furthermore, they thought that problems become disasters when risks that are not properly managed result in significant physical damage to human life, ecosystems, and materials. Most engineering and technology managers would also likely concur that substantial financial losses accompany most disasters. According to one respondent, a so-called natural disaster is almost always triggered or worsened by anthropogenic decisions and actions. That is, if humans avoided building on fault lines, the world would not experience earthquake-generated disasters. This can be extended to environmental disasters. If humans avoided building in flood plains and other hydrologically inappropriate areas, flooding would cause much fewer disasters and the severity would be lessened. Environmental phenomena occur within observable ranges, providing constraints and opportunity. Physical and human geographers agree that environmental conditions are important, but seldom the only criteria for where people live and how they migrate [23].

A primary distinction among disasters is their source. The first classification is whether they are natural or anthropogenic. That is, do they occur naturally or are they principally the result of human actions and activities?

A few prominent sources of and major contributing factors to natural disaster are:

1.Volcanic activity;

2.Severe meteorologicala events, such as weather patterns leading to shipwrecks, plane crashes, and other disasters;

3.Epidemics, pandemics, and other health episodes, e.g., increased occurrence of birth defects or cancer from chemical releases or radiation; new strains of pathogens like an Escherichia coli outbreak or virulent strains of viruses like the influenza pandemic in the early part of the 20th century or the recent COVID-19 pandemic; and

4.Planetary scale disasters, such as changes in the sun's activities, like solar flares that could lead to changes in the earth's electromagnetic field.

Sources of and common contributing factors to anthropogenic disasters include:

1.Large-scale releases of oil during exploration and extraction;

2.Mining accidents, including loss of life due to cave-ins and collapses; loss of property and ecological damage due to release of slag and other mining residues;

3.Collapse of fish stocks and fish kills when streams receive large amounts of nutrients or toxins;

4.Fossil fuel combustion leading to carbon dioxide (CO2) in the atmosphere;

5.Rainforest degradation from slash and burn activities and urban encroachment;

6.Structural failure, including dam, bridge, and infrastructural design and/or maintenance problems, as well as structural failures leading to chemical explosions, asbestos exposures, and radiation releases;

7.Direct environmental pollution such as particulates, ozone, hydrocarbons, and metal compounds in the air, large-scale releases of global greenhouse gases (e.g., chlorofluorocarbons, methane CO2) and water pollution of seas, rivers, and lakes;

8.Warfare and terrorism, such as the loss of life and destruction of crops in the Ukraine-Russia war, environmental devastation due to the Kuwait oil fires, and direct loss of life and long-term health effects from nuclear explosions over Nagasaki and Hiroshima; and

9.Well intended, but error-prone decisions at chemical and nuclear plants, at sea (oil rig and tanker leak disasters) in the air (plane crashes), misuse of pesticides and other chemicals, and improper use of antibiotics (animal feeding operations, leading to resistant strains mentioned of pathogens). Of course, most of these are interrelated. For example, a natural event such as a large storm may only have become a disaster due to human change, such as building levees upstream that increased the flow of water to the disaster area rather than flowing overland upstream.

Risk and precaution

Most of the respondents to our unscientific survey focused on the damage wrought as the distinction between a disaster and a lesser problem. This includes both human-induced events like oil and chemical spills, release of radioactive and otherwise toxic substances into the air, and contamination of ground water via subsurface leaks. It also includes natural events like a volcanic eruption, earthquake, or tsunami. In addition to severity, a disaster has temporal thresholds. That is, an environmental disaster is one that causes long-term damage to the ecosystem and/or human population.

Most often, when assessing an environmental or public health event, it is characterized according to the potential or actual risk associated with an event. Evidence-based risk assessments are conducted to estimate the amount of harm that has occurred or could result from exposure to an environmental stressor. A retrospective risk assessment is part of the root cause analysis following a disaster, which includes every known stressor and outcome. Furthermore, a prospective risk assessment is a valuable follow-up to the root cause analysis, which identifies actual and potential stressors in the same area or other areas where a similar disaster may occur. A stressor can be physical, such electromagnetic radiation, or chemical, such as an air pollutant like carbon monoxide or a water pollutant like 1,4-dioxane, or biological, such as a pathogenic bacterium like E. coli. The risk is generally expressed as the product of a stressor's hazard and exposure:

Equation    (1.1)

Hazard is an inherent trait of the stressor, which expresses a potential outcome based on scientific studies. The outcome can occur relatively rapidly, e.g., within 1 year of exposure is known as an acute hazard. It may also occur long after exposure or after continuous exposure over time, which is known as a chronic hazard, such as neurotoxicity from exposure to the metal lead or carcinogenicity from the exposure to asbestos or benzene.

Humans can contact a substance in various ways in numerous setting. Thus the exposure to a pollutant varies by activities (high for workers who use a chemical, less for workers who may not work with it, but are nearby and breathe the vapors, and even less for other workers). Usually, worker exposure is based on a 5-workday exposure (e.g., 8 or 10  hours), whereas environmental exposures, especially for chronic diseases like cancer, are based on lifetime, 24-hour per day exposures. Thus environmental regulations are often more stringent than occupational regulations when aimed at reducing exposure to a substance [24].

To ascertain possible risks posed during and after a disaster, the first step in a retrospective risk assessment is to identify a general hazard and then determine the exposure scenarios that occurred. As mentioned, this can be followed by a prospective risk assessment wherein scenarios of events that could take place to introduce the potential threat and lead to an effect in the future. The severity of the effect and its likelihood to occur in that scenario is estimated. This combination of each hazard and the exposure likelihood in every disaster scenario represents the damage caused by the disaster in the root cause analysis and the cumulative risk of a pending future disaster in the prospective risk assessment [24].

The relationship between the severity and probability of a risk follows a general equation:

Equation    (1.2)

where risk (R) is a function (f) of the severity (S) and the probability (P) of harm. The risk equation can be simplified to be a product of severity and probability:

Equation    (1.3)

Fig. 1.1 depicts the traditional chemical risk assessment paradigm [25]. It begins with the identification of a hazard, which is a summary of a chemical agent's physicochemical properties and routes and patterns of exposure and a review of toxic and other adverse effects. Hazard identification accounts for metabolic and pharmacokinetic properties based on short-term animal and cell tests, long-term animal (in vivo) testing, and human studies (mainly epidemiological, such as longitudinal and case-control studies). Risk assessors can apply biomarkers of genetic damage (i.e., toxicogenomics) quantitative structure-activity relationship (QSAR) models based on stereochemistry and other chemical descriptions of well-studied compounds to compare to lesser understood substances [27–34]. New methods such as chemoinformaticsb [29,33,35–54] and computational chemistry are also increasingly applied [55–61].

Fig. 1.1

Fig. 1.1 Risk assessment and management paradigm as employed by environmental agencies in the United States. The inner circle includes the steps recommended by the National Research Council. The outer circle indicates the activities that are currently used by regulatory agencies to meet these required steps. Sources: [25,26].

Environmental disasters can also from hazards other than chemical. For example, microbes range in effects from beneficial to extremely hazardous. The Safety in Biotechnology Working Party of the European Federation of Biotechnology [62–65] has identified four risk classes for microorganismsc:

1.Risk class 1. No adverse effect, or very unlikely to produce an adverse effect. Organisms in this class are considered to be safe.

2.Risk class 2. Adverse effects are possible but are unlikely to represent a serious hazard with respect to the value to be protected. Local adverse effects are possible, which can either revert spontaneously (e.g., owing to environmental elasticity and resilience) or be controlled by available treatment or preventive measures. Spread beyond the application area is highly unlikely.

3.Risk class 3. Serious adverse local effects are likely with respect to the value to be protected, but spread beyond the area of application is unlikely. Treatment and/or preventive measures are available.

4.Risk class 4. Serious adverse effects are to be expected with respect to the value to be protected, both locally and outside the area of application. No treatment or preventive measures are available.

These classes indicate that even the safest microbes carry some risk and as uncertainty about an organism increases, safety assurances and measures must be strengthened. That said, most microbes are not considered to be pathogenic. Indeed, harm from a particular species can vary within an exposed population. Certain human subpopulations are susceptible to hazards that may not exist for a large proportion of the population. Also, the risks may be indirect, such as a change induced by the release of genetically altered organism into an environment where they have no natural predators. Thus risk scenarios include not only the effects resulting from the intended purpose of the environmental application but also downstream and side effects that are not part of the desired purpose [66].

Like the hazard identification process for chemicals, the microbe is classified according to inherent properties. It is in the next stage that environmental conditions are taken into account, characterizing different responses to dose in different populations. Both the hazard identification and dose-response information are based on research that is used in the risk analysis [67–69]. For microbes, the highest score for any single species determines the overall risk class for environmental application [62].

Managing exposures to any stressor, including a biological agent, must consider protecting the most vulnerable members of society, especially pregnant women and their yet-to-be-born infants, neonates, and immunocompromised subpopulations. Also, the exposure protections vary by threat. For example, adolescents may be particularly vulnerable to hormonally active agents, given changes in their endocrine system and prolific cell growth [70–73].

Risk can be extrapolated from available knowledge to similar chemical or biological agents with similar characteristics or to yet untested, but similar environmental conditions, e.g., a field study's results in one type of field extrapolated to a different agricultural or environmental remediation setting. In chemical hazard identification, this is accomplished by structural activity relationships [44].

In the United States, up to recently, the ecological risk assessment paradigms have differed from human health risk assessment paradigms. The ecological risk assessment framework (see Fig. 1.2) is based mainly on characterizing exposure and ecological effects. Both exposure and effects are considered during problem formulation [25,75,78–84]. Of late, US government-sponsored human health risk assessments have increasing adopted much of the eco-risk assessment approaches, although they still generally follow the four steps of hazard identification, dose-response assessment, exposure assessment, and risk characterization.

Fig. 1.2

Fig. 1.2 Framework for integrated human health and ecological risk assessment. From: [74]. Sources of information: [74–77].

The process shown in the inner circle of Fig. 1.2 does not target the technical analysis of risk so much as it provides coherence and connections between risk assessment and risk management. In the early 1980s, there was confusion and mixing of the two. For example, a share of the criticism of federal response to environmental disasters, such as those in Love Canal, New York, and Times Beach, Missouri, related to the mixing of scientifically sound studies (risk assessment) and decisions on whether to pursue certain actions (risk management). When carried out simultaneously, decision making could be influenced by the need for immediacy, convenience, or other political and financial motivations, as opposed to a rational and scientifically credible assessment that would underpin management decisions.

At some point, risk assessment and waste management must merge. As mentioned, the final step of both the ecological and human health risk assessment processes is referred to as characterization to mean that both quantitative and qualitative elements of risk analysis, and of the scientific uncertainties in it, should be fully captured by the risk manager [65]. The problem formulation step in the ecological framework has the advantage of providing an analytic-deliberative process early on, since it combines sound science with input from various stakeholders inside and outside of the scientific community. This can be helpful not only in siting waste facilities but also in non-structural solutions to waste problems (e.g., waste minimization, changes in use scenarios, product substitution and life cycle perspectives).

The ecological risk framework calls for the characterization of ecological effects instead of hazard identification used in human health risk assessments. This is because the term hazard has been used in chemical risk assessments to connote either intrinsic effects of a stressor or a margin of safety by comparing a health effect with an estimate of exposure concentration. Thus the term becomes ambiguous when applied to non-chemical hazards, such as those encountered in biological systems.

Specific investigations are needed in the laboratory and field when adverse outcomes may be substantial and small changes may lead to very different functions and behaviors from unknown and insufficiently known chemicals or microbes. For example, a chemical compound may have only been used in highly controlled experiments with little or no information about how it would behave inside of an organism. Often, the proponents of a product would have done substantial research on the benefits and operational aspects of the chemical constituents, but the regulatory agencies and the public may call for more and better information about unintended and yet-to-be-understood consequences and side effects [37,62].

Even when much is known, there often remain large knowledge gaps when trying to estimate environmental impacts. The bacterium Bacillus thuringiensis, for instance, has been applied for several decades as a biological alternative to some chemical pesticides. It has been quite effective when sprayed onto cornfields to eliminate the European corn borer. The current state of knowledge indicates that this bacterium is not specific in the organisms that it targets. What if in the process, B. thuringiensis also kills honeybees? Obviously, this would be a side effect that would not be tolerable from either an ecological or agricultural perspective, given that the same corn crop being protected from the borer also needs the pollinators. Furthermore, physical, chemical, and biological factors can influence these effects, e.g., type of application of Bt can influence the amount of drift toward non-target species. Downstream effects can be even more difficult to predict than side effects, since they not only occur within variable space but also in variable time regimes. For example, risk can arise from both the application method and from the buildup of toxic materials and gene flow following the pesticide drift [66].

Recently, another metric in addition to evidence-based risk assessment has been applied to environmental problems and disasters. The so-called precautionary principle is called for when an activity threatens harm to human health, so that precautionary measures are taken even if some cause and effect relationships are not established scientifically. The concept was first articulated in 1992 as an outcome of the Earth Summit in Rio de Janeiro, Brazil [85]. Those engaging in the behaviors that are building toward the disaster, rather than the public at large, have to prove that they are not contributing to the pending disaster [86–96]. Problems that may affect large numbers of people, cover large geographic areas, and which are irreversible or at least require long periods of time to recover often qualify as disasters. In these cases, prevention is the key and precautionary measures are in order. Precaution is the basis for factors of safety in design and operation, especially if failure can lead to loss of life and major societal harm. Therefore precaution applies to estimates of continental to global scale problems like the long-range transport of pollutants and climate change. The response to stressors has temporal and spatial dependencies. Near-field stressors can result from a spill or emergency situation. At the other extreme, global climate change can result from chronic releases of greenhouse gases with expansive impacts in direct proportion to changes in global climate, including temperature increases in the troposphere and oceans, shifting biomes, sea level rise, and migratory patterns [97].

The spatial and temporal scale of an event does indeed enter into its disaster classification, albeit in a relative way. For example, we used the term long-term. Obviously, an ecosystem that is not sufficiently elastic will experience irreversible and long-term harm more easily than a diverse and elastic system. If the system includes the only habitat of a threatened or endangered species, even an assault that is relatively localized may still cross the damage threshold to be deemed a disaster [97].

The scale and complexity of a disaster affects design and policy decisions regarding pending disasters. For example, continental and planetary scale problems like acid rain and climate change may be treated as disasters even though the damage may not have yet reached disaster thresholds. The design and building of industrial plants and installations of processes can be inherently dangerous and pose a possible risk if the checks and balances are heeded sufficiently. In this instance, this decision may be driven more by uncertainty than risk. That is, certain facilities may need to be excluded completely from hazard zones due to inherently low probability but large risks. In retrospect, for example, some engineers and planners would prohibit the construction of even state-of-the-science nuclear facilities in tsunami zones.

Interestingly, the lessons from hydrologic events are not always heeded. For example, a tsunami is a hydrological event precipitated by a geophysical event. To a statistician, it may be no different, albeit rarer, than any other hydrological event. Thus the statistician will consider the stochasticity of an event to see just how likely its occurrence will be. However, 100-year expectancy does not call for 100-year contingencies. Indeed, a 100-year flood has a 100-year recurrence interval of reaching a certain flood stage, based on historical data, about precipitation and stream characteristics. For example, the probability of a river reaching a stage of 15 ft is calculated to occur once in 100 years. Thus the odds of this flood is 1% each year, so it would not be all that surprising to have such a rain event 3 years in a row, or even more than once per year [98]. A contingency plan properly matched to this probability would also take into account the potential damage. Few would want to live with a 1% or even a 1 in 10,000 probability of one's house burning down in a given year. Factors of safety would be sought much more aggressively. In fact, if the fire risk were that high, land use planners hopefully require that no structures or less fire-prone structures would be allowed. However, it is quite common to see homes rebuilt near beaches and other vulnerable sites immediately after a hurricane.

This may account for the precaution that many have for large-scale projects, even in the face of data support their safety. For example, the news media has reported on several occasions that the track record of hydrofracturing or pipelines from oil shale fields seem sufficient to proceed. Some of the concern with these safety extrapolation is the difference in scale and complexity. Indeed, other extraction techniques have been used and thousands of miles of pipelines already traverse North America. However, the extraction and transport risks are not the same of previous systems. Neither is a complete extrapolation from entirely similar precedents. The quandary of the precautionary principle for engineering and scientific leaders is that it calls for a margin of safety beyond what may directly be construed from science. Many engineers may be uncomfortable with this shift in onus from having to prove that a harm exists to proving that the harm does not exist at the outset. However, it is actually quite similar to other engineering and environmental requirements for ample margins of safety.d Such an approach is difficult, since it usually calls for risk and benefit trade-offs. It could include less travel by individual vehicles and more reliance on mass transit. It may also call for less suburban development and less reliance of fossil fuels. Conversely, it could also lead to even less research risk-taking, which could translate into less scientific advancement [99].

Another aspect of a disaster is how well it can be addressed within the normal range of infrastructures. In this sense, a disaster is any natural, accidental, or deliberate event that overwhelms the ability of local officials and responders to address with community resources. This is a quite useful definition from an engineering and management perspective. That is, even an event that fails to meet a physical threshold, e.g., a relatively low Richter scale reading or slightly elevated concentrations of a toxic chemical, would be disastrous if infrastructure failures led to inordinate and unusual harm. For example, slightly elevated nitrate levels in drinking water would not be an immediate threat to adults but can be fatal to newborns as a result of methemoglobinemia. In fact, the effects of environmental disasters are seldom evenly distributed throughout an affected population. Usually, the effects are most dramatic in the most vulnerable subpopulations, e.g., the very young, the very old, and the infirm.

An ecological disaster can be characterized as structural or functional. Some aspect of an ecosystem has been altered so that it no longer functions efficiently. This was one of the disastrous elements of oil spill disasters, like the Deepwater Horizon oil spill in the Gulf of Mexico, as well as nuclear and chemical contamination events, like dioxins, mercury, and cadmium released from fires and explosions, and the release of isotopes from the meltdowns at Chernobyl and core damage following the earthquake and tsunami in Japan.

Ecosystems are characterized using functional metrics like productivity and species diversity. In the Gulf, the biodiversity was threatened because the crude oil and even the cleaning substances could have differential effects on species, leading to changes in the food webs and potentially damaging the ocean and near-coastal ecosystems for decades. In toxic release disasters, the ecological damage results from biota that are exposed to contaminants as polluting the chemicals cycle through the environment. The damage can be direct, e.g., killing a sufficient number of sensitive biota and changing the biodiversity, or indirect, e.g., involving the bioconcentration of chemicals until the top predators fail to propagate. The damage can also indirectly affect human populations, such as heavy metal concentrations in the food and water supplies.

To scientists and engineers at least, risk is a very straightforward and quantifiable concept: risk equals the probability of some adverse outcome. As the probability approaches zero, the risk decreases. However, if the outcome is potentially devastating, even a very low risk probability must be prevented. Risks are thus a function of probability and consequence [100]. The consequence can take many forms. In the medical and environmental sciences, it is called a hazard. Risk, then, is a function of the particular hazard and the chances of person (or neighborhood or workplace or population) being exposed to the hazard. In the environmental business, this hazard often takes the form of toxicity, although other public health and environmental hazards abound.

Perception

A disaster is value-laden. If the resource (e.g., lake, wetland, pond) sustaining serious environmental damage is one that a particular person places much value, even if it is localized, to that person, its destruction would likely rise to be a disaster. However, destruction of an identical resource in an area not valued by that person likely would not be perceived as a disaster; although they may well sympathize with others. So then, what is a disaster? The term gets used frequently but in myriad ways. Few would disagree that the failure of backup systems during the December 26, 2004, tsunami in the Indian Ocean and its aftermath was a disaster. But a big part of characterizing something as a disaster as opposed to the ubiquitous failures is how the public, or at least a substantial part of it, such as the media, perceive it. Failure occurs all the time. In fact, failure is inevitable. Failure becomes a disaster when events in time and space lead us to conclude that the effects were so severe that it had to be a disaster. It could also be classified as a disaster when engineers made a miscalculation or left out some key information that led to a disaster. Such mistakes may lead to the public perception that the failure was disastrous, compared to an even more severe outcome that was perceived as less preventable, or even inevitable.

Sometimes, a series of events and outcomes are only recognized as a disaster until long after they occur. Environmental disasters, for example, may not be noticed for decades. Chronic diseases like cancer have long periods of separation from first exposure to the causative agent and symptoms of disease, i.e., the so-called latency period. For example, asbestos workers may be exposed for decades before signs of mesothelioma or lung cancer can be diagnosed. Similarly, the relationship between smoking and lung cancer took decades in the face of compelling data before governments became sufficiently aggressive in making the public aware of the dangers of smoking. Insufficient study and underreporting of the exposures and diseases can also obscure linkages between cause and effect, such as the relatively recent linkages between childhood exposures to the metal lead and neurological and developmental diseases. The two problems, i.e., latency period and underreporting can occur together. For example, certain workers may not want to jeopardize their livelihoods and are reluctant to report early symptoms of chronic diseases. Scientists historically have been more likely to study certain demographic groups (e.g., healthy workers) and have avoided others (children, women, and minorities). But, when the results do flood in, such as the lead studies in the latter part of the 20th century or the ongoing arsenic exposures in Bangladesh due to errors in choosing drinking water sources, they are perceived to be public health disasters. Some of these errors may be traced to inherent properties of an agent; in this instance, arsenic. Arsenic's toxicity and bioavailability are affected by its oxidation state. Thus introducing molecular oxygen may have exacerbated the arsenic exposure. Thus engineers and other design professionals should be mindful of even slight changes. The well-meaning aid workers were rightfully concerned with water quantity, but their actions also affected water quality by not only pumping from a contaminated aquifer, but possibly worsening the risk by oxidizing the arsenic.

The foregoing discussion emphasizes that risk perception is a crucial component of risk management. The same facts will be perceived differently by different groups. One group may see the facts as representing a problem that can easily be fixed, while another may perceive the same facts as representing an engineering or public health disaster. Engineers, for example, compared US transportation fatalities in 1992 and found that the modes of transportation had similar numbers of fatalities from accidents, with 775 involving airplanes, 755 from train accidents, and 722 from bicycle accidents [101]. To the public, however, air travel has often been considered to have much higher risk associated with it than that for trains and certainly for bicycles. The researchers concluded that two driving factors may lead to these perceptions: [1] a single event in air crashes leads to large loss of life, with much media attention; and [2] people aboard a large aircraft have virtually no control over their situation. The increased anxiety resulting from highly visible failures and lack of control over outcomes leads to the greater perceived risk. These factors occur in environmental and public health risks. Certain terms are terrifying, like cancer, central nervous system dysfunction, toxics, and ominous-sounding chemical names, like dioxin, polychlorinated biphenyls (PCBs), vinyl chloride, and methyl mercury. In fact, these chemicals are ominous, but many chemicals that are less harmful can also elicit anxieties and associated increased perceived risk. For example, some of our students have recommended banning the substance dihydromonoxide prior to finding out that it is H2O.

Perceived risks may be much greater than actual risks, or they may be much less. So then, how can technical facts be squared with public fears? Like so many engineering concepts, timing and scenarios are crucial.

The risk assessment and risk perception processes differ markedly, as shown in Table 1.1. Holding paramount the health, safety, and welfare of the public gives the engineer no room for spin, but what if the risk perception is very much out of proportion with actual risk. This would mean that employing drastic measures to abate risks that are in fact quite low could result in unnecessarily complicated and costly measures. It may also mean choosing the less acceptable alternative, i.e., one that in the long run may be more costly and deleterious to the environment or public health. Assessment relies on problem identification, data analysis, and risk characterization, including cost–benefit ratios. As evidence, before confronting overwhelming risk data to the contrary, many people believed that wearing safety belts could in some instances result in fatalities such as the difficulty in releasing oneself in an upturned or submerged vehicle. Now-a-days most people accept the data and readily use belts.

Table 1.1

Source: Adapted from [102].

Perception relies on thought processes, including intuition, personal experiences, and personal preferences. Engineers and physical scientists tend to be more comfortable operating in the middle column (using risk assessment processes), while the general public often uses the processes in the far right column. One can liken this to the left-brained engineer or scientists trying to communicate with a right-brained audience. It can be done effectively, so long as preconceived and conventional approaches do not get in the way.

So, both lay groups and our highly motivated and intelligent engineers and scientists of tomorrow have difficulty in parsing perceived and real risks. We can expect the balance between risk assessment and risk perception to be a major challenge in all disaster preparation and response decision making. Sometimes, perception is reality. Disasters are highly stressful and uncertain, so misperceptions are almost guaranteed. Engineering leadership must incorporate ways to prevent and address such miscommunications [18].

Disasters from a societal perspective

We recently polled some very smart people, engineers, scientists, policy makers, researchers, and educators, regarding their definitions of a disaster. One common theme is that a disaster varies from some norm, not just which it is abnormal, but is outside the bounds of expectation. Scientists usually take care to describe a norm. For example, a disaster is an event that occurs beyond so many standard deviations from the mean of similar events. In addition, the disaster must reach some level of adversity. For example, the loss of a single wetland due to a dam breakage may not be considered a disaster, whereas if that same dam breach destroys a town, it would be.

The forgoing example also indicates that disasters are subjective and value-laden. For example, if an endangered species’ only habitat were that wetland loss in the breach, most ecologists and many people would deem that event to be a disaster. Thus the process by which one decides on whether an adverse event is a disaster depends on societal values. That is, the same process under one condition can be a benefit, whereas the same process under a different condition is harmful. For example, major concerns with biotechnology are the release of genetically engineered organisms and attendant materials into the environment, and the release of chemicals from biotechnological operations. Fig. 1.3 demonstrates the similarities between the events that lead to an environmental disaster and those that lead to a successful environmental treatment (e.g., bioremediation). The event trees demonstrate that it is not the act of release (escape, if it is unintended) that renders the chain of events as deleterious or beneficial, but the system in its entirety. In fact, the critical path seldom ends at the final steps shown in Fig. 1.3 but will have continuing impacts. In the case of a deleterious effect in Fig. 1.3A, additional impacts can ensue, such as if the released microbes change biodiversity, which in turn drifts into standing agricultural crops and damages the food supply. Or, if the deleterious effect of the microbial release is a virulent form of a bacterium, which not only causes a health effect from those who consume contaminated drinking water, but which may lead to cross-resistant pathogens, so that existing antibiotics become less effective in treating numerous other diseases.

Fig. 1.3

Fig. 1.3 Critical paths of a microbial disaster scenario (A) versus a bioremediation success scenario (B). In both scenarios, a microbial population (either genetically modified or non-genetically modified) is released into the environment. The principal difference is that the effects in A are unwanted and deleterious, whereas the effects in B are desired and beneficial. Source: [66].

Even a successful bioremediation project, such as that shown in Fig. 1.3B, can experience other unexpected events and can occur after the specific success. For example, genetically modified bacteria have been widely and successfully used to degrade oil spills. If the bacteria, which have a propensity to break down hydrocarbons do not stop at the spill, but begin to degrade asphalt roads (i.e., the bugs do not distinguish between the preferred electron acceptors and donors in an oil spill or asphalt), this is a downstream, negative impact of a successful bioremediation effort (see Fig. 1.4). Furthermore, if the microbes do not follow the usual script, where the next generation are completely sterile but are able to reproduce and become part of the formerly exclusively natural microbial species, the traits of the population may be altered in unknown ways.

Fig. 1.4

Fig. 1.4 Same scenario as Fig. 1.3 but with subsequent or coincidental events that were unexpected or not fully addressed, leading to downstream, environmental, or public health impacts. Source: [66].

Fig. 1.5 provides a similar scenario for chemical (abiotic) releases (treatment, if intentional). This is actually an example of addressing a risk, but at the same time, introducing another, so-called contravening risk. For example, if thousands of people are intentionally exposed to a toxic substance, is this an immoral act? Sometimes, of course, it is. For example, exposing people intentionally to Sarin gas is an act of terrorism. But exposing people to a very toxic pesticide is an act of protecting public health. In the latter scenario, the risks of not applying the pesticide had to outweigh the risks of applying it.

Fig. 1.5

Fig. 1.5 Critical paths of a chemical disaster scenario (A) versus a public health pesticide application scenario (B). In both scenarios, a chemical compound is released into the environment. The principal difference is that the effects in A are unwanted and deleterious, whereas the left side of B shows effects that are desired and beneficial, which can be eradication of a vector (e.g., mosquito) that carries disease (e.g., malaria). The same critical path can be applied to herbicides for weed control, rodenticides for rodents that carry disease, and fungicides for prevention of crop damage. The right side of B is quite similar to the chemical disaster scenario in A; that is, the pesticide that would be useful in one scenario is simply a chemical contaminant in another. Examples include pesticide spills (e.g., in dicofol in Lake Apopka, Florida), or more subtle scenarios, such as the buildup of persistent pesticides in sediment for years or decades. Source: [66].

The uncertainties and complexities also indicate that controlling and managing these agents often entails risk tradeoffs, since every one of the scenarios, even the decision not to take any action, has contravening risks. For example, the persistent organic pollutants (POPs) all have helped to meet society's needs, such as disease control (1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane, DDT), food supply (aldrin, dieldrin, hexachlorobenzene), and distribution of electricity (PCBs). But these uses were always accompanied by contravening risks. Disputes between the pros and cons of DDT, for example, centered around environmental and public health risks versus the commercial. People are justifiably concerned that even though the use of a number of pesticides, including DDT, has been banned in Canada and the United States, they may still be exposed by importing food that has been grown where these pesticides are not banned. In fact, Western nations may continue to allow the pesticides to be formulated at home but do not allow their application and use. But in the long run (short-term and long-term, extensive spatial impact boxes in Fig. 1.5), the pesticide comes back in the important products treated with the domestically banned pesticide. This is known as the circle of poisons.

Does this analogy hold for disasters? Indeed, it does. Take Katrina. Allowing the building of roads, homes, and other structures in a sensitive ecosystem provided localized benefits but ignored the laws of nature. It was merely a matter of time, in the opinion of many earth scientists and hydrologists, before the Mississippi River reclaimed its flood plain. The complexity of the riverine system was not respected. The land use was treated as a series of simple, reductionist actions, rather than as a complex system.

Risks versus risks can also come into play. In other words, it is not simply a matter of taking an action, e.g., banning worldwide use of DDT, which leads to many benefits, e.g., less eggshell thinning of endangered birds and less cases of cancer. No, it sometimes comes down to trading off one risk for another. Since there are yet to be reliable substitutes for DDT in treating disease-bearing insects, policy makers must decide between ecological and wildlife risks and human disease risk. Also, since DDT has been linked to some chronic effects like cancer and endocrine disruption, how can these be balanced against expected increases in deaths from malaria and other diseases where DDT is part of the strategy for reducing outbreaks? Is it appropriate for economically developed nations to push for restrictions and bans on products that can cause major problems in the health of people living in developing countries? Some have even accused Western nations of eco-imperialism when they attempt to foist temperate climate solutions onto tropical, developing countries. That is, we are exporting fixes based upon one set of values (anti-cancer, ecological) that are incongruent with another set of values of other cultures (primacy of acute diseases over chronic effects, e.g., thousands of cases of malaria are more important to some than a few cases of cancer, and certainly more important than threats to the bald eagle from a global reservoir of persistent pesticides).

Finding substitutes for chemicals that work well on target pests can be very difficult. This is the case for DDT. In fact, the chemicals that have been formulated to replace have either been found to be more dangerous, e.g., aldrin and dieldrin (which have also been subsequently banned), or much less effective in the developing world (e.g., pyrethroids). For example, spraying DDT in huts in tropical and subtropical environments, fewer mosquitoes are found compared to untreated huts. This likely has much to do with the persistence of DDT in mud structures compared to the higher chemical reactivity of pyrethroid pesticides.

The POPs provide abundant lessons about risk trade-offs. First, the engineer must ensure that recommendations are based upon sound science. While seemingly obvious, this lesson is seldom easy to put into practice. Sound science can be trumped by perceived risk, such as when a chemical with an ominous-sounding name is uncovered in a community, leading the neighbors to call for its removal. However, the toxicity may belie the name. The chemical may have very low acute toxicity, has never been associated with cancer in any animal or human studies, and is not regulated by any agency. This hardly allays the neighbors’ fears. The engineer's job is not done by declaring that removal of the chemical is not necessary, even though the declaration is absolutely right. The community deserves clear and understandable information before we can expect any capitulation.

Second, removal and remediation efforts are entirely never risk free. To some extent, they always represent risk shifting in time and space. A spike in exposures is possible during the early stages of removal and treatment, as the chemical may have been a place and form that made this less available until actions were taken. Due in part to this initial exposure, the concept of natural attenuation has recently gained greater acceptance within the environmental community. However, the engineer should expect some resistance from the local community when they are informed that the best solution is to do little or nothing but to allow nature (i.e., indigenous microbes) take its course (doing nothing could be interpreted as intellectual laziness!).

Third, the mathematics of benefits and costs is inexact. Finding the best engineering solution is seldom captured with a benefit-cost ratio. Opportunity costs and risks are associated with taking no action (e.g., Hurricanes Ian and Katrina disasters present opportunities to save valuable wetlands and to enhance a shoreline by not developing and not rebuilding major portions of the Gulf region). The costs in time and money are not the only reasons for avoiding an environmental action. Constructing the new wetland or adding sand to the shoreline could inadvertently attract tourists and other users who could end up presenting new and greater threats to the community's environment.

Arguably, biotechnological solutions, such as the use of genetically modified organisms to produce pesticide substitutes, are even more complicated than dealing with abiotic systems. As such, the bioengineer will need tools to optimize the risk management.

Figs. 1.3–1.5 illustrate the complexity of biological systems. The interactions, modes of action, and mechanistic behaviors are incompletely and poorly understood. Much of what we know about biology at the subcellular level is more empirical and descriptive than foundational and predictive. Thus there are so many uncertainties about these processes that even a seemingly small change (tweaking) of any part of the genomic system can induce unexpected consequences [103]. Some have likened the need for a life-cycle view and the need for humility under such uncertainty. It is much easier to view the consequences of a decision as an independent event. In fact, few decisions are independent. They are affected by and affect other components of a system.

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