Principles of air quality management

We next look at the health effects of the criteria air pollutants and those that areconsidered toxic or hazardous, and the effects of those contaminants on the humanbody.. His projects h

Tai Lieu Chat Luong

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Griffin, Roger D.

Principles of air quality management / Roger D Griffin 2nd ed.

p cm.

Includes bibliographical references and index.

ISBN 0-8493-7099-X (alk paper)

1 Air quality management I Title

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Still dedicated to those who seek the Truth in all things,

and to Him Who is

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Preface to the Second Edition

In the years since the first edition, we have seen new trends that this author did notthink possible when he began his environmental career in 1969 Today there are farfewer “smog alerts,” far fewer acute-health impacts, a far greater acceptance of cleanfuels and clean technologies, new engine systems, and a far greater understanding

of the sources of air emissions — both natural and man-made (Air quality ments are detailed in Chapter 10.)

improve-On an international scale, air quality issues being addressed include the concernfor indoor air quality in developing nations, the push for clean fuels worldwide, andthe search for newer, less polluting technologies for industry and control systems

It is worth noting that the stratospheric ozone layer over Antarctica — once predicted

as taking decades to improve — is increasing

If the estimated methane reserves of 400 million tcf (trillion cubic feet) ered in gas hydrates offshore can be accessed, the entire energy paradigm will shiftdramatically to clean fuels

discov-While our goal is the same as in our first edition — “giving the reader a firmgrasp of the principles that make up the broad field of air quality, its pollution andits management” — we are also celebrating the successes we have seen over thepast 40 years of a concerted effort directed toward clean air I would like to paytribute to the thousands who have spent myriad hours studying the atmosphere,devising technologies for clean fuels, clean engines and new control systems, inves-tigating health effects, reviewing historical information on climate, monitoring theair, preparing new management strategies, evaluating rules and regulations, andguiding the energies and industries of a modern society in new directions To you

we say thank you

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Preface to the First Edition

In order to understand and manage our air quality resources, it is necessary to gain

a fundamental understanding of the principles that govern our ability to do so.From a local perspective, it may be considered desirable to install huge fans inorder to “blow the smog away,” but from a technological and scientific perspective

it is not feasible Likewise, from a regional or continental perspective, it is notacceptable to merely transfer air contaminants from one location to another one bydilution or “blowing it away.”

It is therefore the purpose of this book to give the reader a firm grasp of theprinciples that make up the broad field of air quality, its pollution, and its manage-ment Starting from the basic definitions of air and types of air pollution, we willfollow some of its history through the present century From that perspective, wewill look at the terms used: air quality, emissions, standards and classifications ofpollutants, and the production of secondary air pollution or photochemical smog

We next look at the health effects of the criteria air pollutants and those that areconsidered toxic or hazardous, and the effects of those contaminants on the humanbody Air pollutant damages to materials and vegetation are also reviewed Thestandards of acceptable air quality from the perspective of health impacts (chronicthrough emergency episode concentrations) and the techniques for measuring airquality are also reviewed

We approach the sources of air contaminants from an anthropogenic as well asgeogenic and biogenic perspective Between sources and receptors we look at howcontaminants are dispersed into the atmosphere from a local, regional, and globalperspective From these studies come an evaluation of the different models used tocalculate dispersion and the models used to predict ambient air quality

Federal laws and regulations as well as regional perspectives are summarizedand evaluated Control technologies that are available for both stationary sourcesand mobile sources are reviewed From these, we are able to evaluate the possiblemanagement options for limiting emissions and optimizing air pollutant strategies.Global air quality concerns, relative global emissions, and the alternative viewsare evaluated from the perspective of management options that may be available tosociety at large Of particular concern are those that may influence long-term airquality and health Finally, we will be looking at indoor air quality and the futuretrends in air quality management approaches, with their limitations

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The Author

Roger D Griffin has more than 35 years of technical and management expertise

as a result of working on numerous environmental problems He has in-depthexperience in the design, evaluation, and testing of existing and planned combustion,air pollution, waste-to-energy, and hazardous waste sources and control technologies,combined with several years of advanced study of pollutant formation and dispersionfrom point and area sources

He has served as an expert witness in cases involving air toxics, contaminatedproperties, and remediation His master’s thesis was a field validation of the Gaussianplume dispersion model; the antecedent of EPA’s ISC and AERMOD dispersionmodels He has conducted remedial investigations at Superfund sites

Mr Griffin has worked with local government agencies throughout his career,including the County of Orange (California), and the South Coast Air QualityManagement District and its predecessor agencies He has held positions with theEcology Auto companies (director of Environmental Compliance), Converse Con-sultants (president and managing officer), CH2M-Hill, US Ecology, and KVB Engi-neering He has served in various capacities in his career: analyzing air samples fortrace pollutants; and as a field inspector, source testing specialist, permit processingengineer, project manager, and principal-in-charge

His projects have included working on secondary aluminum foundries; ing dispersion modeling and health risk assessments for permits to operate combinedcycle power systems; providing expert witness testimony for cases involving haz-ardous air pollutant emissions from a railroad tank car derailment and spill; per-forming extensive NOx testing and control programs on standard and alternativefuels; and providing on-site reviews and evaluations of operating European andUnited States incineration facilities, determining hazardous and toxic emission lev-els, emissions test methods, and best control technologies for toxic air contaminants

perform-Mr Griffin has worked on biomass fuel systems (rice hull burner and cow manurecombustion systems); performed alternative control technologies and process changeevaluations for effectiveness and costs to control odors

His other activities have included preparing hearing board cases, testifying as

an expert witness, supervising special studies, preparing emission inventories, andevaluating technological and economic impacts of New Source Review regulation

In addition, he has worked for industrial clients in the food preparation, metallurgical,chemical, petroleum, and power generation industries

In his earlier years, Mr Griffin supervised a source test team, was responsiblefor ambient air monitoring instrument calibrations, and advised on methods of airsampling analysis

He taught for 10 years at UCLA and UC–Irvine in their Environmental neering Extension program, teaching air quality and hazardous materials7099_C000.fm Page xi Monday, July 24, 2006 2:52 PM

Engi-management He has a master’s degree in engineering, a bachelor’s degree in istry, and is a registered chemical engineer in California.

chem-CONTRIBUTOR Benjamin K Griffin practices law as an associate for Bois & Macdonald, anenvironmental law firm in Irvine, California In his practice, he has worked with theSouth Coast Air Quality Management District (SCAQMD), the California Depart-ment of Toxic Substances Control (DTSC), regional water quality control boards,the Los Angeles County Health and Hazardous Materials Division, and the County

of San Diego Department of Environmental Health He works on matters regardingCERCLA, RCRA, USTCF, and NPL listed sites He also has worked on claimsinvolving construction delay and inverse condemnation

He earned his J.D degree from Pepperdine University School of Law While inlaw school, Mr Griffin distinguished himself as a member of the Law School HonorBoard, serving as prosecutor During his second year of law school he was selected

as a Blackstone Fellow

Mr Griffin earned his B.A degree from The Citadel, with department honors,

in political science, international politics, and military affairs

Mr Griffin is a member of the State Bar of California, the U.S District Court,Central District of California, the American Bar Association, and the EnvironmentalLaw Section of the Orange County Bar Association

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The following individuals are acknowledged for their contributions to this book and

to a greater understanding of the field of air quality management:

Dr Kathryn Kelly of Delta Toxicology, Inc

Michael Oard, Retired Meteorologist

Dr James Pitts of the University of California, Riverside

Dr Scott Samuelson of the University of California, Irvine

Dr Larry Vardiman of the Institute of Creation Research

A special acknowledgment is given to my wife, Dr Avice Marie Griffin, withoutwhose encouragement this book would not have been possible

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Chapter 1 The Atmosphere and Its Contaminants 1

History of Air Pollution 1

Medieval Experiences 1

Industrialization 2

The Early 20th Century 2

The Great London Smog Disaster — December 1952 3

Late 20th and Early 21st Centuries 4

Terms and Definitions 4

Ambient Air 4

Criteria and Noncriteria Air Pollutants 5

Emissions 6

The Epidemiologic Model 7

Components of the Atmosphere 7

Physical Characteristics 8

Standard Conditions 9

Dew Point and Humidity 9

States of Air Pollutants 10

Pollutant Gas Features 10

Particulate Features 10

Contaminant Classifications 13

Primary Contaminants 13

Natural Emissions 14

Anthropogenic Emissions 14

Secondary Contaminants 14

Photochemical Smog 14

Air Quality Management Aspects of Photochemical Reactions 18

Chapter 2 Effects of Air Pollution 21

Time Effects and Sensitivities 21

Acute versus Chronic 21

Sensitive Populations 22

Criteria versus Noncriteria Air Pollutants 22

Criteria Air Pollutant Effects 23

Ozone 23

Sulfur Dioxide 24

Particulate Matter 26

Nitrogen Dioxide 26

Carbon Monoxide 27

Lead 27 7099_C000.fm Page xv Monday, July 24, 2006 2:52 PM

Basic Principles of Toxicology 28

Sources of Health Effects Information 28

Dose–Response 29

Routes of Exposure 30

Inhalation 30

Response to Airborne Chemicals 30

The Lungs 31

The Central Nervous System 33

The Liver 33

The Kidneys 33

The Blood 33

The Reproductive System 33

The Cardiovascular System 34

The Skeletal System 34

Other Factors to Consider 34

Classes of Health Effects 35

Latency 36

Carcinogens 36

Mutagens 36

Teratogens 36

Effects on the Ecosystem 37

Effects on Vegetation 37

Plant Structure 37

Leaf Structure 37

Plant Injury 38

Acid Precipitation Effects 38

Pollutant Interactions 39

Economic Losses Caused by Vegetation Effects 39

Effects on Materials 39

Textiles 40

Building Materials 40

Metal Corrosion 41

Surface Coatings 42

Documents and Manuscripts 42

Rubber 42

Effects on Animals 43

Economic Losses 43

Chapter 3 Air Quality Standards and Monitoring 45

Standards 45

Acceptable Levels 46

Ambient Air Standards and Exposures 48

National 48

International Air Pollution Levels 50 7099_C000.fm Page xvi Monday, July 24, 2006 2:52 PM

The Pollution Standard Index 51

Episodic Standards 52

Noncriteria Air Contaminant Standards 53

Occupational Derived Standards 53

Risk Assessment 54

The Risk Assessment Process 54

Hazard Identification 54

Dose–Response Assessment 55

Exposure Assessment 56

Risk Characterization 57

Uncertainties 57

Uncertainties in Toxicity 57

Uncertainties in Modeled Exposures 58

Screening Level Approaches 58

Carcinogen Hazards 58

Acceptable Air Quality 61

Monitoring Ambient Air Quality 61

Measurement Techniques 63

Cumulative Samplers 64

Continuous Analyzers 66

Chapter 4 Sources and Measurement Methodologies 69

Global Sources 70

Geogenic 70

Biogenic 70

Anthropogenic 71

Global Emissions 72

Air Pollution Sinks 74

Biological Sinks 74

Mechanical Sinks 74

Photochemical Sinks 75

Anthropogenic Air Emissions 76

Combustion 76

Fuels for Combustion Reactions 77

Coal 77

Liquid Fuels 79

Natural Gas 80

Efficiency and Emissions 81

Enthalpy Considerations 81

Air and Fuel Considerations 82

Combustion Chemistry 82

Air-to-Fuel Ratio Considerations 83

Combustion Systems 84 7099_C000.fm Page xvii Monday, July 24, 2006 2:52 PM

Evaporative Emissions 85

Evaporative Classes 87

Fugitive Emissions 88

Waste-Related Emissions 89

Landfills 89

Treatment-Related Emissions 91

Criteria Air Pollutant Formation 91

Source Inventories of Criteria Pollutants 92

Transportation 93

Fuel Combustion 93

Industrial Processes 94

Miscellaneous 95

Comparisons by Category 95

Hazardous Air Emissions 96

Quantification of Emissions 97

Source Testing 97

Continuous Emissions Monitoring 97

Carbon Balance 98

Composition 98

Emission Factors 98

Fugitives 99

Accuracy and Applicability 99

Chapter 5 Meteorology, Dispersion, and Modeling 101

Earth’s Energy and Radiation 101

Temperature and Global Air Movements 103

Global Circulation Cells 104

Jet Streams 105

Surface Effects 105

Other Forces 107

Patterns of High and Low Pressure 107

Friction 111

Horizontal and Vertical Air Patterns 111

Atmospheric Stability 111

Vertical Mixing 113

Horizontal Air Movements 113

Regional Air Pollution Meteorology 115

Inversions 115

Types of Inversions 115

Southern California — The Classic Example 117

Sea and Land Breezes 117

Other Dispersive Characteristics of the Atmosphere 119

Valley Effects 119

Chimney Effect 121

Vegetation Effects 121 7099_C000.fm Page xviii Monday, July 24, 2006 2:52 PM

Mountain Effects 122

Urban Heat Island Effects 122

Local Air Pollutant Dispersion 123

Point Sources and Plume Dispersion 123

Plume Rise 124

Plume Shape 125

Line Sources 127

Area Sources 128

Dispersion Modeling 128

Point-Source Modeling 129

Model Averaging Time 131

Plume Model Modifications 131

Line-Source Models 133

Area Modeling 133

Catastrophic Releases 133

Visibility 134

Mathematical Models 134

Planning Based 134

Receptor Based 136

Statistical Based 136

Chapter 6 Stationary-Source Control Approaches 139

Source Reduction 139

Management and Operational Changes 140

Fugitive Emissions 141

Product Storage Control 142

Materials Changes 144

Process-Optimizing Actions 145

Combustion Modifications 146

Fuels and Fuel Modification 151

Efficiency 151

Secondary Utilization 151

Fuel Switching 152

Fuel Blending 152

Fuel Cleaning 153

Additives 154

Fuel Modifications 154

Fuel Refining 156

Planning and Design 156

Geographic Location 156

Lower-Emission Systems 157

Greater Efficiency 158

Repowering 158

Emissions Characterization 158

Collection of Air Contaminants 159 7099_C000.fm Page xix Monday, July 24, 2006 2:52 PM

Air Pollution Control Approaches 162

Gas Control Technologies 162

Absorbers 163

Adsorbers 164

Condensers 165

Thermal Oxidation 166

Particulate Control Technologies 167

Mechanical Collectors 168

Fabric Filters 169

Wet Scrubbers 171

Electrostatic Precipitators 172

Combination Units 173

Combustion Gas Control Technologies 174

Carbon Monoxide and Combustible Carbon Gases 174

Sulfur Dioxide 174

Oxides of Nitrogen 174

Selective Catalytic Reduction 176

Selective Noncatalytic Reduction 176

Oxidative Systems 177

Technology Comparisons 177

Control System Hardware Considerations 178

Chapter 7 Mobile Sources and Control Approaches 179

Engines and Air Pollutant Emissions 179

Pollutant Formation in Spark-Ignited Engines 181

Bulk Gas Pollutant–Formation Region 181

Surface Pollutant–Formation Region 182

Four-Stroke Pollutant Mechanisms 183

Lesser Sources of Carbon Gas Pollutant Emissions 183

Fuel Composition and Exhaust Emissions 185

Diesel Ignition Emission Characteristics 185

Pollutant Patterns 188

Hydrocarbon Emissions from Trip Cycles 188

Engine Thermodynamic Cycles 189

Hybrid Internal Combustion Engines 192

ICE Emission-Control Options 193

Effects of Operating Conditions 193

Spark Timing 193

Compression Ratio 193

Engine Speed 194

Engine Power 194

Engine Temperatures 195

Engine Cleanliness 195

Design Influences on ICEs 196

Two-Stage Combustion 197 7099_C000.fm Page xx Monday, July 24, 2006 2:52 PM

External Control Approaches 198Fuel Recapture Systems 198Catalyst Systems 198Diesel Particulate Controls 200Fuel Change Effects 200Diesel Fuels 204Alternatives and the Future 205Alternative Fuels 205Alternative Mechanical Design and Efficiency Approaches 206Alternative Power Systems 206

Chapter 8 Global Concerns 209The Challenge 210Data and Records 210Intercontinental Pollutant Transport 211The Data 212Conclusions 213Stratospheric Ozone 213Radiation Primer 213Stratospheric Ozone Formation 215Early Observations 216The Response 216Other Sources and Variations 216Lab Studies 217Antarctic Studies 217

UV Data and Other Impacts 218Alternatives 219Acid Deposition 220Water Plus Air 220Water Plus Soils 220Acid Rain Studies 221The NAPAP Findings 222Conclusions 224Global Climate Change 224Historical Perspective 225Current Concerns 227Measurements 231Other Considerations 235Feedbacks 235Models 236Recent Findings 237Alternative Views 238Increased Yields 239Other Agricultural Effects 2407099_C000.fm Page xxi Monday, July 24, 2006 2:52 PM

Chapter 9 Air Quality Laws and Regulations 243General Law Approaches 243Public Nuisance 243Private Nuisance 244Recent Approaches 244The Process of Regulation 245Role of the Public in Rule Making 245Environmental Justice 246Levels of Authority 246Federal Preemption 246Federal Laws Affecting Air Quality Management 247Pre-1990 Air Quality Acts and Effects 247Implementation Plans 248Monitoring and Limiting Emissions 248Prevention of Significant Deterioration 248Emergency Episodes 249Hazardous Air Pollutants 250Global Concerns 250Federal Environmental Statutes 250Toxic Substances Control Act 250Resource Conservation and Recovery Act 250Comprehensive Emergency Response, Compensation, and

Liability Act 251The Clean Air Act 252Title I — Attainment and Maintenance of the NAAQS 253Ozone Nonattainment Requirements 254Additional Ozone Strategies 256Carbon Monoxide Nonattainment Provisions 258PM10 Nonattainment Areas 259PM2.5 Nonattainment Areas 260Title II — Mobile Source Provisions 260Light-Duty Vehicle Standards 260Tailpipe Toxics 261Emissions Control 261Reformulated Gasoline Fuel Requirements 262Phase II Reformulated Gasoline Performance Standards 262California Low-Emission Vehicle II Regulations 263Title III — Hazardous Air Pollutant Program 263Toxic Release Inventory Program 264HAP Sources 264Area Sources: Urban Air Toxics Strategy 266SIP Revisions 266HAP Permits 266Special Studies 266Clean Air Mercury Rule 2667099_C000.fm Page xxii Monday, July 24, 2006 2:52 PM

Prevention of Accidental Releases 267Solid Waste Combustion 268Title IV — Acid Deposition Program 268

SO2 Provisions — Clean Air Interstate Rule 2005 Effect 268Market-Based Allowance Program 269

NOx Provisions — Budget Training Program 269Other Provisions 270Title V — Operating Permits 270Permit Program Requirements 271Fees 271Other Provisions 272Valid Permits 273Title VI — Stratospheric Ozone Protection 273Recapture and Recycling 274Labeling 274Title VII — Enforcement Provisions 274Clean Air Crimes 274Title VIII — Miscellaneous Provisions 275Visibility and Source Receptor Concepts 275Grand Canyon Visibility Transport Commission 275International Treaties 276Montreal Protocol 276Kyoto Accords 276The Influence of Nonregulatory Governmental Actions 277Court Decisions 278

Chapter 10 Management, Trends, and Indoor Air Quality 279Elements of Air Quality Management 280Nonregulatory Air Quality Management Approaches 281Trends 282Trends in Emissions 282Trends in the Extreme Ozone Area 283Trends in Strategy 286Fuels and Transportation 286Small Sources 287Governance 287Hazardous Air Pollutants 288Lifestyle Impacts 289Stationary Sources 289Natural Sources 290The Outlook 290Indoor Air Quality 291Environmental Tobacco Smoke 294Radon 2957099_C000.fm Page xxiii Monday, July 24, 2006 2:52 PM

Radon in Building Sources 297Soil 297Water 298Building Materials 299Measurement and Action Levels 299House Characteristics and Radon Gas Entry 300Mitigation 300Other Indoor Air Contaminant Concerns 302Public Buildings 304Indoor Air Pollution in Developing Countries 305List of Acronyms 307Glossary 311Bibliography 325Index 3317099_C000.fm Page xxiv Monday, July 24, 2006 2:52 PM

Fumifugium, 1661

HISTORY OF AIR POLLUTION

Air pollution has been around as long as man has walked the earth Indeed, in theearliest extant writings, dating from the dawn of civilization, air emissions fromforging operations for bronze, iron, and other implements were well known (Genesis,Chapter 4), as were the emissions from smoking fires and blazing torches (Genesis,Chapter 15) Natural emissions from volcanoes and forest fires were well knownand a part of everyday life The usual response was to let nature take its course andblow air contaminants away or else to emigrate to areas with breathable air

It has been known for millennia that people with certain occupations, such asminers, incurred diseases of the lungs and respiratory system Today we know thatmany of these effects were not only induced by fine particles and toxic metals butalso by carbon monoxide Radon gas also was one of the contributing factors tominers’ lung disease from the 15th through the 20th centuries in the ErzgebirgMountains in central and eastern Germany

Emissions from cooking, heating, and fires in general were also well known.Apart from nature, the sources of contamination were simple solid fuels and metalworking operations Odors also were a part of common life The common approach

to air quality management was to stay out of “bad air” (mal aria),or out of areas

in which refuse, garbage, and human corpses were deposited in ancient times

up air quality in England was the prohibition on burning soft coal in 1273 By theend of the 13th century, there was considerable agitation about the use of “sea-coal,”7099_book.fm Page 1 Friday, July 14, 2006 3:13 PM

2 Principles of Air Quality Management, Second Edition

and air quality complaints were mounting In 1306, King Edward I attempted todrastically curtail the use of coal in London by passing a law stating that “no coalwas to be burned by industry and artisans during Parliament.”

known attempt to provide an acknowledgment of the effects of air pollution on thehealth of all persons; to point out the industries and fuels that caused the problem;

to offer a variety of management strategies to deal with smoke, its deleteriousqualities, and its dispersion; and to offer some remedies Later societal responsesincluded building chimneys as urbanization and population centers grew Thesechimneys provided some relief in the immediate vicinity of the pollutants, but theycontributed to an overall deterioration of air quality in the surrounding areas

I NDUSTRIALIZATION

With the rise of industrialization in the 18th and 19th centuries, the effects of airpollutant emissions were noted on greater portions of the population Air qualitymanagement options (i.e., controls and prohibitions), however, generally laggedbehind societal concerns for managing sanitation, water supply, and solid waste.Odors from the Thames River in the late 1850s were reported to make life in Londonalmost intolerable, and industrial centers such as the Ruhr Valley in Germany wereknown to significantly affect life in general, and health and appearance in particular The effects of air pollution on vegetation in the United States, primarily sulfuroxides and particulate matter containing heavy metals, were seen first hand in theCopper Hill area of southeastern Tennessee near Ducktown (the hometown of theauthor’s father) Before 1864, the area was covered with pine forests and shrubs,but following the founding of the copper smelter, vast quantities of air pollutantswere emitted directly into the air without controls, and the surrounding countrysidewas totally denuded This included 7,000 acres of forest and over 17,000 acres ofland that could no longer support vegetation other than a few grasses It took over

100 years for extremely hardy vegetation to once again come back, and that regrowthoccurred only following institution of air pollution controls on the source

T HE E ARLY 20 TH C ENTURY

It was not until the 20th century that air quality management approaches (i.e.,primarily smoke and odor abatement measures) began to make their appearance In

1906, Frederick G Cottrell invented the first practical air pollution control device:

an electrostatic precipitator to control emissions of acid droplets from a sulfuric acidmanufacturing plant

The term smog, a contraction of the words smoke and fog, was popularized inGreat Britain as a result of a report by a Dr H.A des Voeux, a London physicianwho worked in the field of public health, to the Manchester Conference of the SmokeAbatement League in 1911 It concerned conditions in Scotland in which the com-bination of smoke, sulfurous gases, and fog were believed to have claimed over1,000 lives in Glasgow and Edinburgh in 1909

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The Atmosphere and Its Contaminants 3

Man-made air emissions were generated in the early 20th century from twogeneral sources: industrial operations and the generation of electrical power Most

of these operations were driven by the combustion of solid fuels Air emissions werewithout controls and were directly released into the atmosphere through a chimney

or stack Early control efforts were aimed at either recovery of materials (i.e., acid)emitted from the plant or abating smoke emissions The first method of quantifyingsmoke density for regulatory purposes, using the Ringlemann visual method, wasadopted before World War I

During this era, efforts were made at understanding not only emissions but alsotheir dispersion The earliest attempts to understand the dispersion of air contami-nants were made by observers and meteorologists of the British Army artillery corpsduring World War I, and afterward by observations of antiaircraft shell bursts

As industrialization proceeded in the early decades of the 20th century, icant air pollutant “episodes” were noted, such as that which occurred in the MeuseValley in Belgium in 1930 There, meteorological conditions contributed to airstagnation, which led to a build up of pollutant concentrations caused by industrialsites in the vicinity In this incident, approximately 60 people died and hundreds ofothers became ill

signif-It was not until the post–World War II era, however, that a better understanding

of air pollution was gained and control technology approaches were instituted Inthe United States in the 1940s, in addition to efforts by pioneers in understandingair pollutants, changes were also made in the fuels used (i.e., from coal to oil andgas) More significantly, the number and types of sources changed dramatically.However, the most important effect was caused by the dramatic increase in thenumber of automobiles in the United States following World War II

In the late 1940s and early 1950s in Los Angeles, a new type of air pollutionwas noted: photochemical smog We now know this type of air pollution to be made

up of photochemical oxidant gases Since that time, photochemical air pollution hasbeen found in virtually every urbanized area in the world It results from a combi-nation of weather patterns, sunlight, and specific emissions interacting to formground-level ozone

T HE G REAT L ONDON S MOG D ISASTER — D ECEMBER 1952

Air pollution reached its worst in the Great London Smog Disaster of December

1952 In this event, all of the worst possible contributing factors of air pollution (airstagnation, a temperature inversion, extreme cold, high usage of dirty fuels, theswitch from electric trolleys to diesel buses for public transport, lack of controls onindustrial sources, etc.) combined to cause a siege of bad air quality that lasted forabout two weeks

Recent research has determined that the mortality estimates of about 4,000 excessdeaths in the period immediately following the event were low by a factor of three.Actually about 12,000 people died as a direct result of the Great London SmogDisaster, and thousands more were sickened Even today that event is being studiedand new findings made (i.e., the initial estimate of the excess deaths being only7099_book.fm Page 3 Friday, July 14, 2006 3:13 PM

4 Principles of Air Quality Management, Second Edition

among the elderly was wrong, the majority of deaths were among the old age group, probably as a result of their higher outdoor exposures)

45–65-year-L ATE 20 TH AND E ARLY 21 ST C ENTURIES

Only in the last decades of the 20th and the first decade of the 21st century haveair quality management strategies taken hold In the last 30 years, there have beensignificant reversals in earlier air quality trends from increasingly poor air quality

to increasingly healthy air quality This change has come about as a result ofdedicated people and of societal decisions to pursue clean air as a priority Mostsignificant, this change has come at a time when the worldwide population has beenincreasing

TERMS AND DEFINITIONS

To clarify our understanding of air quality management issues, it is necessary totake a look at the terms that are in use throughout this field of study

Our air is composed primarily of two simple gases: oxygen and nitrogen It isthe one substance without which people cannot survive for more than about threeminutes Occupying less than 1/1,000,000 the mass of the earth, the atmosphere iscritical to life as we know it However, “pure air” is not an easily defined term Although we may note the average concentrations of gases and other materialsthat make up the atmosphere, we are called on to make a distinction between theair we breathe, termed the ambient air, and those trace constituents that may beconsidered pollutants or contaminants Contaminants may be considered any mate-rials other than the permanent gases seen in Table 1.1 A pollutant, in contrast, hasthe connotation of being derived from mankind’s activity Again, this is an artificialdistinction, as gases, dust, and particles may be generated by natural processes (e.g.,volcanic eruptions), as well as by grinding operations that make a useful product,such as cement The health, visibility, and materials or vegetation effects may bethe same whether the source is natural or man-made

In general, we are mostly concerned with air pollutants Pollutants are a mate concern of society in dealing with air quality and its management, whereascontaminants may be accepted as a part of the natural world in which we live Inone sense, windblown dust may be both a contaminant and pollutant The distinction

legiti-is further blurred when adopted air quality regulations are generic; that legiti-is, whenthey are based on concentration measurements regardless of source Thus, air con-taminants may be confused with air pollutants

A MBIENT A IR

The term ambient air refers to that portion of the atmosphere that is in the “breathingzone” of the inhabitants of the earth’s surface As such, it is limited to the lowerseveral hundred feet of the earth’s atmosphere The ambient air and, in particular,7099_book.fm Page 4 Friday, July 14, 2006 3:13 PM

The Atmosphere and Its Contaminants 5

those contaminants that may exist in the ambient air are of major concern becausethey determine the effects on human health, materials, and vegetation

C RITERIA AND N ONCRITERIA A IR P OLLUTANTS

There are two basic categories of contaminants in the ambient air that are of concern.These two categories are termed criteria pollutants and noncriteria pollutants.Criteria air pollutants are those air contaminants for which numerical concen-tration limits have been set as the dividing line between acceptable air quality andpoor or unhealthy air quality

The national ambient air quality standard is the concentration of a given airpollutant in the ambient air (over a specified period of time) below which the U.S.Environmental Protection Agency believes that there are no long-term adverse healtheffects The criteria air pollutants include four gases and two solids:

TABLE 1.1 Composition of the Clean Atmosphere Near Sea Level

Constituent

Chemical Formula

* Dry basis.

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6 Principles of Air Quality Management, Second Edition

• Nitrogen dioxide (NO2)

• Sulfur dioxide (SO2)

• Carbon monoxide (CO)

• Ozone (O3)

• Particulate matter (PM10)

• Lead (Pb)

The criteria pollutants have been studied in some cases (e.g., sulfur dioxide) for over

100 years, and their human health and vegetation effects are well documented Thenoncriteria pollutants are those contaminants designated as toxic or hazard-ous by legislation or regulation They fall into two further subcategories, depending

on the legislation that defines them In general, the hazardous air pollutants maypose a variety of health effects (irritation, asphyxia, etc.), whereas the toxics focus

on one physiological response (i.e., toxicity)

Noncriteria air pollutants have been studied in industrial hygiene settings In theambient air, noncriteria pollutants tend to be several orders of magnitude lower inconcentration than the criteria pollutants For instance, it would not be uncommon

to find ambient carbon monoxide in the parts per million range, whereas ambientconcentrations of a hazardous air pollutant, such as benzene, would be in the partsper billion range

The concentrations of ambient air pollutants are expressed in terms of either amass per unit volume ratio, such as µg/m3 (micrograms per cubic meter), or a purevolumetric ratio (i.e., volumes of contaminant per million volumes of air) Therelationship between the two concentration expressions is a function of the molecularweight of the contaminant in question and the standard conditions referenced in thesetting of the ambient air quality standards The conversion between mass units andvolumetric ratios at standard temperature and pressure is

µg/m3 = ppm × MW ÷ 0.02445 = ppb × MW ÷ 24.45, (1.1)where

µg/m3 = micrograms per cubic meter

ppm = parts per million by volume

MW = molecular weight of the contaminant

ppb = parts per billion

It should be remembered that ambient air quality standards have differing timeperiods over which the concentration is to be calculated In some cases (e.g., ozone),these concentrations are expressed as parts per hundred million, or pphm, averagedover either one or eight hours

E MISSIONS

Emissions are air contaminant mass releases to the atmosphere from a source Theymay be from a tail pipe, vent, or stack, though some may be airborne, such as thosefrom aircraft

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The Atmosphere and Its Contaminants 7

Emission regulations are expressed in one of two ways: the first is by a massemission rate, such as pounds per hour, tons per year, or milligrams per second Thesecond is in terms of a concentration in a release, such as parts per million or grainsper standard dry cubic foot (gr/SDCF)

Standards for either expression are set by regulation, depending on the aircontaminant, the source, and the regulatory jurisdiction Mass emission rates arecalculated from a measured concentration and from calculations of total gas flowper unit time Emission standards expressed in concentration units were derivedfrom early measurements of air pollutants at their sources In these early efforts tocontrol air pollution, this was the quickest method to determine compliance at asource without having to quantify the mass emission rates

T HE E PIDEMIOLOGIC M ODEL

Mass emission rates and ambient air quality concentrations are related by thesource/transport/receptor model In the public health field, this is termed the epide-miologic model and relates a source through a mode of transmission to the receptor Modeling of the transport phenomenon by which diffusion and dispersion occuryields a calculated downwind ambient pollutant gas concentration Recent air qualitymanagement approaches for hazardous air pollutants and air toxics have used theepidemiologic model to relate health effects to emissions by using various dispersionmodels (see Chapter 5)

COMPONENTS OF THE ATMOSPHERE

Fundamental to understanding air quality management is a basic understanding ofthe atmosphere itself, its composition, functions, movements, and effects

The major components of the atmosphere on a dry basis, as seen earlier, arenitrogen, at about 78%, and oxygen, at about 21%, leaving about 1% for all theother components Neither nitrogen nor oxygen is passive — they have significanteffects of their own, particularly when reacting with each other to form other aircontaminants The gas concentrations seen in Table 1.1 vary somewhat from point

to point across the surface of the globe

The major components in the atmosphere function first in bulk transport Thisincludes the transport of energy from east to west and from pole to equator, as well

as the transport of contamination from a source to a receptor Nitrogen and oxygenalso participate in the nitrogen cycle, which is critical for the functions of photo-synthesis and food production Atmospheric temperature and pressure are functions

of these bulk gases

The minor components of the atmosphere include the gases water vapor (H2O)and carbon dioxide (CO2) These components vary much more in concentration, byseveral percent in the case of water and by several parts per million for carbondioxide These two gases have major effects in and of themselves

First, water participates in the hydrologic cycle on which life itself depends Inaddition, water in the vapor or gaseous state is the most important gas contributing

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8 Principles of Air Quality Management, Second Edition

substance because at the earth’s surface, it exists in all three material states: solid,liquid, and gas Water performs its major functions in the life processes as a liquidover a narrow temperature range of about 100˚K in a universe that tends to operateeither near absolute zero or at millions of degrees

The other unique properties of water are the large amounts of energy per unitmass that are either absorbed or released when water moves between solid and liquid

or between liquid and gaseous states In the atmosphere, these movements havetremendous effects on the energy balance in the atmosphere and are responsible forthe weather

Carbon dioxide contributes to the greenhouse effect but has a much lessercontribution However, CO2 is the key participant in the carbon cycle (photosynthesisand respiration), without which life could not exist

The other materials that exist in the atmosphere at highly variable concentrationsare the trace components These include the carbon gases, carbon monoxide (CO)and methane (CH4); the nitrogen gases, ammonia (NH3), oxides of nitrogen (NOx =

NO and NO2), and nitrous oxide (N2O); the sulfur gases, hydrogen sulfide (H2S)and sulfur dioxide (SO2); ozone (O3); and particulate matter (finely divided solid orliquid particles suspended in the atmosphere by mechanical mixing or brownianmotion)

These trace components appear to be closely intertwined, both in terms of theirinfluence and of their reactions with each other in photochemistry For instance,methane (CH4) is not an inert gas but appears as a greenhouse gas and participatesextensively in reactions with carbon monoxide, oxygen, and hydroxyl radicals toform ozone These trace contaminants also have a major influence on health, damage

to materials, and effects on vegetation and crops

P HYSICAL C HARACTERISTICS

Air is a mixture of all of these gases It has an approximate molecular weight of 29

As a gas, it follows the physical gas laws Within a somewhat restricted operatingtemperature (ambient conditions: typically 0˚–50˚C), it follows the ideal gas law:

where

P = absolute pressure

V = volume of the gas parcel in question

n= number of moles of gas in the parcel

R = gas law constant

T= absolute temperature

Air is also a fluid and therefore tends to move under the influence of externalforces, as would any fluid such as water However, because it is a gas, it has noeffective shear strength and will change its volume and density as the pressure andtemperature change

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The Atmosphere and Its Contaminants 9

Each component in the atmosphere has its own partial pressure that is

indepen-dent of all other gas components Because of this, the molecular weight of the

atmosphere changes slightly as one increases elevation

S TANDARD C ONDITIONS

Because the atmosphere varies from place to place in terms of temperature (T),

density (ρ), and pressure (P), a reference pressure has been defined as one “standard

atmosphere at sea level.” Sometimes the standard atmosphere is considered under

“dry” conditions In these cases, all water vapor is subtracted and the remaining gas

constituents are calculated on a “dry basis.”

The equivalencies between pressure measurement units are

One Standard Atmosphere = 1010 mb = 760 mm of Hg = 14.7 psi, (1.3)

where

m = millibar

mm Hg = millimeters of mercury column height

psi = pounds per square inch

Standard temperatures tend to vary depending on the reference For the U.S

EPA, the reference temperature is 20˚C For other air quality jurisdictions the

standard temperature is 60˚F In other technical fields the standard temperature may

be 32˚F or 273˚K

Density is the mass-to-volume ratio of any given parcel of air The correction

of a given density to a standard condition is a straight proportionality between the

ambient P and T and the reference density at standard T and P For 14.7 psi and

60˚F, the dry air density is 0.0763 lb/cubic foot At 760 mmHg and 20˚C, the dry

air density is 1.356 g/L

D EW P OINT AND H UMIDITY

As the temperature of a gas parcel increases, its capacity to hold water vapor

increases The measure of the amount of moisture or water vapor in a given parcel

of air is called its absolute humidity (i.e., milligrams of moisture per cubic meter

of air) If we compare the actual amount of moisture in an air parcel to the maximum

that it could hold at a given temperature, we have relative humidity It is expressed

in percentage of the maximum moisture possible for the given temperature and

atmosphere pressure being considered If a parcel of air contains all of the possible

water that it could theoretically hold, we term that condition “saturation,” or 100%

relative humidity

Because saturation is a function of temperature, if we have a parcel of air that

is already saturated at a given temperature (such as 90˚F), and that parcel of air is

further cooled, the water vapor will tend to condense out to form droplets of liquid

water The water will then be in the form of a fog If other constituents are present

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10 Principles of Air Quality Management, Second Edition

in that parcel of air (such as particles), larger droplets will precipitate out To

condense water from gas to liquid, a large amount of heat (“the heat of

condensa-tion”) must be removed This latter characteristic has significant effects on the

weather and on pollutant transport

STATES OF AIR POLLUTANTS

In understanding the physical state of air pollutants, we realize that we are dealing

with all three states of matter: solid, liquid, and gas Each has its own characteristics

and effects

P OLLUTANT G AS F EATURES

The major pollutant gases include sulfur dioxide, carbon monoxide, volatile organic

compounds, nitric oxide, and nitrogen dioxide Thus, they obey the gas laws outlined

earlier The major pollutant gases are also reactive — either by way of photochemical

reactions or by direct reaction with materials, vegetation, or living tissues There are

significant size features: these gas molecules are on the order of 0.0005 micrometers

(µ, or microns) in diameter They mix in a local environment by diffusion and in

the atmosphere at large by convection

There is little visibility effect from the true pollutant gases other than changes

to the color of the atmosphere as we view it For instance, NO2 absorbs light in the

ultraviolet end of the visible spectrum Therefore, when NO2 is present in moderate

concentrations, we see a yellow-to-brown coloration Another salient feature is that

these gases are primarily acids, and thus they participate in all of the acid reactions

common to the field of chemistry The health effects of these gases are very important

Finally, there are high annual emission rates (tonnage) in all nations for these

anthropogenic emissions In the United States, about 135 million metric tons per

year of gaseous air pollutants are emitted to the atmosphere Gaseous emissions are

well in excess of 95% of all U.S air pollutant emissions, and about two-thirds of

this total is carbon monoxide

P ARTICULATE F EATURES

Particles or particulate matter that are suspended in the atmosphere (either solids or

liquid droplets) are termed aerosols Particulate matter in solid form is not

particu-larly reactive unless it encounters liquids (i.e., condensing water vapor or other

liquids) Liquid droplets are also termed particulate matter (or particulates in some

jurisdictions) The pH of the droplet, as well as its composition and the amount of

dissolved material in the droplet, is of concern Particulate matter represents

approx-imately 3% of the total anthropogenic burden of emissions in the United States, at

approximately 4 million metric tons per year

The size of particulate matter in the atmosphere is highly variable, ranging from

less than 0.01 µ to over 100 µ In Figure 1.1, we see the typical ambient air trimodal

distribution of particulate diameters versus number density These three size

group-ings are generally attributable to different sources

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The Atmosphere and Its Contaminants 11

Figure 1.2 indicates the particulate size ranges of various materials as found inurban environments

The largest particles, those with an aerodynamic diameter larger than about 10 µ,are generated either by natural causes (windblown dust) or by attrition or grinding

of naturally occurring materials, such as sand, coal, lime, and so on The largestones settle out soonest (under quiet conditions) with a constant velocity within afairly short distance They are governed by the Stokes law, which relates the settlingvelocity to the particle density and diameter

FIGURE 1.1 Modal distribution of atmospheric particles.

FIGURE 1.2 Size ranges of common atmospheric particles.

Nuclei mode Accumulation mode

Particle diameter, ( µm)

100

Sea salt

Fly ash Carbon black

Pollen Tobacco smoke

Cement dust

Oil smoke Metallurgical dust and fumes Smog

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12 Principles of Air Quality Management, Second Edition

At the other end of the size distribution are the ultrafine particles — those inthe 0.002–0.1µ range These particles behave like gas molecules and exhibit Brown-ian motion; thus, they remain suspended in the atmosphere for long periods of time.These particles are in the condensation nuclei size range because they are generallyformed by the condensation of gases or vapors into liquid or solid droplets Sources of these ultrafine particulates include combustion and fumes from met-allurgical operations Key features of these particles are: (1) they are very reactive

on their surfaces, (2) they tend not to remain in that particle size, and (3) they serve

as sites for the deposition of heavy metals, such as selenium, arsenic, and lead.The middle distribution, roughly between 0.1 and 2 µ in diameter, forms the

accumulation group These particles are termed accumulation because this size range

is the final resting place of particles from the other two regions Ultrafine particles

in the condensation nuclei range agglomerate and grow to an optimum diameterbetween approximately 0.3 and 0.5 µ under the influence of Brownian motion andcondensation processes The growth tends to stop there because of surface chargeand surface tension effects Coarse particles will continue to break down because

of mechanical action and weathering They tend to accumulate in the 1–2 µ diametersizes Particulates in the less than 2.5 µ (particulate matter 2.5) diameter range areconsidered fine particles primarily because of their deposition sites within the lungs.Those larger than 2.5 µ are termed coarse particles

These diameters do not represent the true physical diameter of the particles.Particles tend to be irregular in shape except for liquid droplets The aerodynamicdiameter is defined as the theoretical diameter of the particle in question which isequivalent to a spherical particle of unit density (1 g per cubic centimeter) Moni-toring instruments are calibrated to the unit density spherical particle and, therefore,measure particulate size in terms of aerodynamic diameter Optical measurements,

of course, reveal a wide variety of particle shapes and aspect ratios

Liquid aerosols are less well defined Several considerations differentiate themfrom gases and solid particulates These aerosols are typically classified in the0.01–1.0 aerodynamic diameter size range Also, because aerosol diameters exist atthe wave lengths of visible light, optical scattering occurs An aerosol’s ability tointerfere with light transmission is also related to its mass concentration

The components of aerosols include soil-derived crustal materials; water; organiccompounds; water-soluble acids such as HCl, SO2, and carbon dioxide; ions derivedfrom other, originally gaseous, pollutants such as ammonia; and finally, elementssuch as soot or black carbon in their elemental forms, mixed with the other materials

As such, aerosols are heterogeneous mixtures, and therefore, their composition varieswidely depending on their location, the time of the year, meteorological conditions,and so on

Aerosols are reactive and will participate in the formation of other compoundswithin the droplet itself Figure 1.3 shows an idealized schematic of the composition

of atmospheric aerosols and their sources

Two of the greatest effects of aerosols are on health and visibility As a result

of the size of aerosols, they are deposited deep in the lungs (in the alveoli), wherethey accumulate From there other chemical contaminants are carried across tissuemembranes into the body

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The Atmosphere and Its Contaminants 13

CONTAMINANT CLASSIFICATIONS

Air contaminants can be classified in one of two major categories depending on thegeneration mode — primary or secondary emissions The latter are produced byfurther reactions in the air or within liquid aerosols

or derived from living organisms

FIGURE 1.3 Idealized schematic of the composition of atmospheric aerosols.

Secondary organic C

Condensible organics

Gaseous organics

Gas phase photochemistry

Sea salt + dust

Primary organic carbon

Combustion process emissions

14 Principles of Air Quality Management, Second Edition

Natural Emissions

The geogenic source contaminants include the sulfur gases (SO2 and H2S), methanecarbon dioxide, particulates (minerals), chlorides and other ions such as sodium(from volcanos and sea salt aerosols), and the petroleum gases The latter are derivedfrom within the earth’s crust and contain all of the organic compounds normallyfound in crude oil systems from methane to the heaviest asphaltic compounds.The biogenic gases include hydrogen and all of the carbon-based gases derivedfrom biological activity The processes include photosynthesis, metabolic action,decomposition of living matter, and emissions from plants and animals Among thecarbon gases are CO, CO2, methane, CH3Cl, and the terpenes (organic compounds —the basic structures of which are formed from isoprene, a five-carbon olefinic chaincompound) Terpenes are photochemically reactive and represent significant emis-sions, which lead to secondary reactions in the atmosphere Emission rates of thosecompounds are a strong function of temperature and are released by land-based plants

Anthropogenic Emissions

The anthropogenic pollutants (i.e., those generated by man’s activities) include COand sulfur dioxide, hydrochloric acid, and NOx, as well as the halogenated solventssuch as perchloroethylene In addition, particulate matter, covering all of the sizeranges noted earlier, is generated from anthropogenic activities Petroleum-relatedgases are also included in the anthropogenic category, as they are also released intothe atmosphere from mankind’s activities in handling, processing, transporting,reacting, and combusting petroleum-based materials

S ECONDARY C ONTAMINANTS

Secondary air contaminants are those that are produced by reactions either in thegas phase or in aerosols suspended in the atmosphere “Oxidants” (ozone plus PANplus NO2) are the most important class of secondary pollutants produced in the gasphase

Particulate matter is produced from primary pollutant gases For example, NO(from combustion or natural causes) is initially oxidized to NO2 and, ultimately, tonitric acid and ionic nitrates Likewise, sulfur dioxide is oxidized in the atmosphere

to sulfur trioxide, which, in the presence of moisture, forms sulfuric acid and,ultimately, particulate sulfates

Within an aerosol, further reactions occur to change the chemical compositionand potential health effects of the droplet The acid forms of sulfur and nitrogenoxide gases will react with naturally occurring ammonia to form ammonium sulfateand nitrate salts

The Atmosphere and Its Contaminants 15

common pattern of several of the pollutant gases that were noted during the course

of a typical “smoggy” day in Southern California (Figure 1.4)

The initial levels of contaminants remained low and fairly constant until aboutsunrise During the morning hours, sharp increases in NO and nonmethane hydro-carbon concentrations were noted It was observed that this rise corresponded to thestart up and driving of mobile sources of combustion contaminants — principally

NO and hydrocarbons from gasoline-powered automobiles

By late morning, the concentrations of hydrocarbons and NO began to fall atabout the same time that NO2 concentrations began to rise This was followed atmidday by declining concentrations of NO2 and increasing concentrations of oxi-dants, principally ozone As the afternoon proceeded and the sun dipped, it wasnoted that oxidant concentrations also began falling off This drop was followed by

a late afternoon surge in NO and NO2 readings, which then dropped off and leveledout as the evening progressed

The researchers concluded that there was a relationship between sunlight, carbons/volatile organic compounds, NO, and NO2 This deduction led others toinvestigate the relationship between organic gases and oxides of nitrogen in smogchamber studies in the presence of sunlight to form oxidants and ozone

hydro-Carbon monoxide concentrations (Figure 1.5) also showed a diurnal pattern withconcentration increases in the early morning and late afternoon periods CO is not

a direct participant in the majority of the reactions producing ozone in theatmosphere — CO competes with the formation of ozone by reacting with OH freeradicals to produce a free hydrogen atom The latter reacts rapidly with oxygen to

FIGURE 1.4 Daily variation in air pollutant levels.

NO

NO2Oxidant

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