Aerosol Science
Technology and Applications

AEROSOL SCIENCE
TECHNOLOGY AND APPLICATIONS

Aerosols influence many areas of our daily life. They are at the core of environmental problems such as global warming, photochemical smog and poor air quality. They can also have diverse effects on human health, where exposure occurs in both outdoor and indoor environments.

However, aerosols can have beneficial effects too; the delivery of drugs to the lungs, the delivery of fuels for combustion and the production of nanomaterials all rely on aerosols. Advances in particle measurement technologies have made it possible to take advantage of rapid changes in both particle size and concentration. Likewise, aerosols can now be produced in a controlled fashion. Reviewing many technological applications together with the current scientific status of aerosol modelling and measurements, this book includes:

• Satellite aerosol remote sensing
• The effects of aerosols on climate change
• Air pollution and health
• Pharmaceutical aerosols and pulmonary drug delivery
• Bioaerosols and hospital infections
• Particle emissions from vehicles
• The safety of emerging nanomaterials
• Radioactive aerosols: tracers of atmospheric processes

With the importance of this topic brought to the public's attention after the eruption of the Icelandic volcano Eyjafjallajökull, this book provides a timely, concise and accessible overview of the many facets of aerosol science.

List of Contributors xiii

Preface xv

1. Introduction 1
Mihalis Lazaridis and Ian Colbeck

1.1 Introduction 1

1.2 Size and Shape 5

1.3 Size Distribution 6

1.4 Chemical Composition 10

1.5 Measurements and Sampling 11

References 12

2. Aerosol Dynamics 15
Mihalis Lazaridis and Yannis Drossinos

2.1 Introduction 15

2.2 General Dynamic Equation 17

2.2.1 Discrete Particle Size Distribution 18

2.2.2 Continuous Particle Size Distribution 19

2.3 Nucleation: New Particle Formation 19

2.3.1 Classical Nucleation Theory 20

2.3.2 Multicomponent Nucleation 22

2.3.3 Heterogeneous Nucleation 23

2.3.4 Atmospheric Nucleation 24

2.4 Growth by Condensation 26

2.5 Coagulation and Agglomeration 27

2.5.1 Brownian Coagulation 28

2.5.2 Agglomeration 28

2.6 Deposition Mechanisms 32

2.6.1 Stokes Law 32

2.6.2 Gravitational Settling 32

2.6.3 Deposition by Diffusion 34

2.6.4 Deposition by Impaction 34

2.6.5 Phoretic Effects 34

2.6.6 Atmospheric Aerosol Deposition 35

2.6.7 Deposition in the Human Respiratory Tract 36

2.7 Resuspension 38

2.7.1 Monolayer Resuspension 38

2.7.2 Multilayer Resuspension 39

References 41

3. Recommendations for Aerosol Sampling 45
Alfred Wiedensohler, Wolfram Birmili, Jean-Philippe Putaud, and John Ogren

3.1 Introduction 45

3.2 Guidelines for Standardized Aerosol Sampling 46

3.2.1 General Recommendations 46

3.2.2 Standardization of Aerosol Inlets 47

3.2.3 Humidity Control 49

3.3 Concrete Sampling Configurations 53

3.3.1 General Aspects of Particle Motion 53

3.3.2 Laminar Flow Sampling Configuration 54

3.3.3 Turbulent Flow Sampling Configuration 55

3.4 Artifact-Free Sampling for Organic Carbon Analysis 57

Acknowledgements 59

References 59

4. Aerosol Instrumentation 61
Da-Ren Chen and David Y. H. Pui

4.1 Introduction 61

4.2 General Strategy 62

4.3 Aerosol Sampling Inlets and Transport 63

4.4 Integral Moment Measurement 64

4.4.1 Total Number Concentration Measurement: Condensation Particle Counter (CPC) 65

4.4.2 Total Mass Concentration Measurement: Quartz-Crystal Microbalance (QCM) and Tapered-Element Oscillating Microbalance (TEOM) 66

4.4.3 Light-Scattering Photometers and Nephelometers 67

4.5 Particle Surface Area Measurement 68

4.6 Size-Distribution Measurement 70

4.6.1 Techniques based on Particle–Light Interaction 70

4.6.2 Techniques based on Particle Inertia 71

4.6.3 Techniques based on Particle Electrical Mobility 74

4.6.4 Techniques based on Particle Diffusion 77

4.7 Chemical Composition Measurement 78

4.8 Conclusion 80

References 82

5. Filtration Mechanisms 89
Sarah Dunnett

5.1 Introduction 89

5.2 Deposition Mechanisms 91

5.2.1 Flow Models 92

5.2.2 Diffusional Deposition 96

5.2.3 Deposition by Interception 98

5.2.4 Deposition due to Inertial Impaction 99

5.2.5 Gravitational Deposition 100

5.2.6 Electrostatic Deposition 100

5.3 Factors Affecting Efficiency 104

5.3.1 Particle Rebound 104

5.3.2 Particle Loading 106

5.4 Filter Randomness 109

5.5 Applications 109

5.6 Conclusions 110

Nomenclature 110

References 113

6. Remote Sensing of Atmospheric Aerosols 119
Sagnik Dey and Sachchida Nand Tripathi

6.1 Introduction 119

6.2 Surface-Based Remote Sensing 120

6.2.1 Passive Remote Sensing 120

6.2.2 Active Remote Sensing 126

6.3 Satellite-Based Remote Sensing 126

6.3.1 Passive Remote Sensing 127

6.3.2 Active Spaceborne Lidar 135

6.3.3 Applications of Satellite-Based Aerosol Products 136

6.4 Summary and Future Requirements 141

Acknowledgements 142

References 142

7. Atmospheric Particle Nucleation 153
Mikko Sipilä, Katrianne Lehtipalo, and Markku Kulmala

7.1 General Relevance 153

7.2 Detection of Atmospheric Nanoparticles 156

7.2.1 Condensation Particle Counting 156

7.2.2 Electrostatic Methods 158

7.2.3 Mass Spectrometric Methods for Cluster Detection 160

7.3 Atmospheric Observations of New Particle Formation 163

7.3.1 Nucleation 163

7.3.2 Growth 165

7.4 Laboratory Experiments 166

7.4.1 Sulfuric Acid Nucleation 166

7.4.2 Hunt for Compound X 168

7.5 Concluding Remarks and Future Challenges 169

References 170

8. Atmospheric Aerosols and Climate Impacts 181
Maria Kanakidou

8.1 Introduction 181

8.2 Global Aerosol Distributions 181

8.3 Aerosol Climate Impacts 182

8.4 Simulations of Global Aerosol Distributions 186

8.5 Extinction of Radiation by Aerosols (Direct Effect) 190

8.5.1 Aerosol Optical Depth and Direct Radiative Forcing of Aerosol Components 193

8.6 Aerosols and Clouds (Indirect Effect) 194

8.6.1 How Aerosols Become CCNs and Grow into Cloud Droplets 195

8.7 Radiative Forcing Estimates 200

8.8 The Way Forward 203

References 203

9. Air Pollution and Health and the Role of Aerosols 207
Pat Goodman and Otto Hänninen

9.1 Background 207

9.2 Size Fractions 208

9.3 Which Pollution Particle Sizes Are Important? 209

9.4 What Health Outcomes Are Associated with Exposure to Air Pollution? 209

9.5 Sources of Atmospheric Aerosols 210

9.6 Particle Deposition in the Lungs 210

9.7 Aerosol Interaction Mechanisms in the Human Body 211

9.8 Human Respiratory Outcomes and Aerosol Exposure 215

9.9 Cardiovascular Outcomes and Aerosol Exposure 215

9.10 Conclusions and Recommendations 216

References 216

10. Pharmaceutical Aerosols and Pulmonary Drug Delivery 221
Darragh Murnane, Victoria Hutter, and Marie Harang

10.1 Introduction 221

10.2 Pharmaceutical Aerosols in Disease Treatment 223

10.2.1 Asthma 223

10.2.2 Chronic Obstructive Pulmonary Disease 224

10.2.3 Cystic Fibrosis 224

10.2.4 Respiratory Tract Infection 225

10.2.5 Beyond the Lung: Systemic Drug Delivery 225

10.3 Aerosol Physicochemical Properties of Importance in Lung Deposition 226

10.4 The Fate of Inhaled Aerosol Particles in the Lung 228

10.4.1 Paracellular Transport 229

10.4.2 Transcellular Transport 229

10.4.3 Carrier-Mediated Transport 230

10.4.4 Models for Determining the Fate of Inhaled Aerosols 231

10.5 Production of Inhalable Particles 233

10.5.1 Particle Attrition and Milling 233

10.5.2 Constructive Particle Production 235

10.6 Aerosol Generation and Delivery Systems for Pulmonary Therapy 237

10.6.1 Nebulised Disease Therapies 237

10.6.2 Pressurised Metered-Dose Inhaler Systems 241

10.6.3 Dry-Powder Inhalation 248

10.6.4 Advancing Drug-Delivery Strategies 252

10.7 Product Performance Testing 253

10.7.1 Total-Emitted-Dose Testing 253

10.7.2 Aerodynamic Particle Size Determination: Inertial Impaction Analysis 253

10.8 Conclusion and Outlook 255

References 255

11. Bioaerosols and Hospital Infections 271
Ka man Lai, Zaheer Ahmad Nasir, and Jonathon Taylor

11.1 The Importance of Bioaerosols and Infections 271

11.2 Bioaerosol-Related Infections in Hospitals 272

11.3 Bioaerosol Properties and Deposition in Human Respiratory Systems 275

11.4 Chain of Infection and Infection Control in Hospitals 275

11.5 Application of Aerosol Science and Technology in Infection Control 277

11.5.1 Understanding Hospital Aerobiology and Infection Control 277

11.5.2 Bioaerosol Experiments and Models 280

11.5.3 Numerical Analysis of Particle Dispersion in Hospitals 281

11.5.4 Air-Cleaning Technologies 282

11.6 Conclusion 285

References 285

12. Nanostructured Material Synthesis in the Gas Phase 291
Peter V. Pikhitsa and Mansoo Choi

12.1 Introduction 291

12.2 Aerosol-Based Synthesis 292

12.3 Flame Synthesis 292

12.4 Flame and Laser Synthesis 299

12.5 Laser-Induced Synthesis 302

12.6 Metal-Powder Combustion 309

12.7 Spark Discharge 313

12.8 Assembling Useful Nanostructures 314

12.9 Conclusions 322

References 323

13. The Safety of Emerging Inorganic and Carbon Nanomaterials 327
L. Reijnders

13.1 Introduction 327

13.2 Human Health and Inhaled Persistent Engineered Inorganic and Carbon Nanomaterials 330

13.3 Human Health Hazards and Risks Linked to the Ingestion of Persistent Inorganic Nanomaterials 333

13.4 Ecotoxicity of Persistent Inorganic and Carbon Nanomaterials 335

13.5 Conclusion 336

References 336

14. Environmental Health in Built Environments 345
Zaheer Ahmad Nasir

14.1 Environmental Hazards and Built Environments 345

14.2 Particulate Contaminants 348

14.2.1 Transport and Behaviour of Particles in Built Environments 349

14.3 Gas Contaminants 351

14.3.1 Biological Hazards 351

14.3.2 Physical Hazards 357

14.3.3 Ergonomic Hazards 358

14.3.4 Ventilation and Environmental Hazards 359

14.3.5 Energy-Efficient Built Environments, Climate Change and Environmental Health 361

References 362

15. Particle Emissions from Vehicles 369
Jonathan Symonds

15.1 Introduction 369

15.2 Engine Concepts and Technologies 370

15.2.1 Air–Fuel Mixture 370

15.2.2 Spark-Ignition Engines 371

15.2.3 Compression-Ignition Engines 372

15.2.4 Two-Stroke Engines 372

15.2.5 Gas-Turbine Engines 373

15.3 Particle Formation 373

15.3.1 In-Cylinder Formation 373

15.3.2 Evolution in the Exhaust and Aftertreatment Systems 375

15.3.3 Noncombustion Particle Sources 375

15.3.4 Evolution in the Environment 376

15.4 Impact of Vehicle Particle Emissions 376

15.4.1 Health and Environmental Effects 376

15.4.2 Legislation 376

15.5 Sampling and Measurement Techniques 378

15.5.1 Sample Handling 378

15.5.2 Mass Measurement 379

15.5.3 Solid-Particle-Number Measurement 380

15.5.4 Sizing Techniques 382

15.5.5 Morphology Determination 382

15.6 Amelioration Techniques 385

15.6.1 Fuel Composition 385

15.6.2 Control by Engine Design and Calibration 385

15.6.3 Particulate Filters 386

Acknowledgements 388

References 388

16. Movement of Bioaerosols in the Atmosphere and the Consequences for Climate and Microbial Evolution 393
Cindy E. Morris, Christel Leyronas, and Philippe C. Nicot

16.1 Introduction 393

16.2 Emission: Launch into the Atmosphere 395

16.2.1 Active Release 397

16.2.2 Passive Release 397

16.2.3 Quantifying Emissions 398

16.3 Transport in the Earth’s Boundary Layer 399

16.3.1 Motors of Transport 399

16.3.2 Quantifying Near-Surface Flux 400

16.4 Long-Distance Transport: From the Boundary Layer into the Free Troposphere 404

16.4.1 Scale of Horizontal Long-Distance Transport 404

16.4.2 Altitude of Long-Distance Transport 405

16.5 Interaction of Microbial Aerosols with Atmospheric Processes 406

16.6 Implications of Aerial Transport for Microbial Evolutionary History 407

References 410

17. Disinfection of Airborne Organisms by Ultraviolet-C Radiation and Sunlight 417
Jana S. Kesavan and Jose-Luis Sagripanti

17.1 Introduction 417

17.2 UV Radiation 418

17.3 Sunlight 419

17.4 Selected Organisms 421

17.4.1 Bacterial Endospores 421

17.4.2 Vegetative Bacteria 422

17.4.3 Viruses 423

17.5 Effects of UV Light on Aerosolized Organisms 423

17.5.1 Cell Damage Caused By UV Radiation 423

17.5.2 Photorepair 424

17.5.3 Typical Survival Curve for UV Exposure 425

17.5.4 The UV Rate Constant 427

17.5.5 RH and Temperature Effects 428

17.5.6 Bacterial Clusters 429

17.6 Disinfection of Rooms Using UV-C Radiation 429

17.7 Sunlight Exposure Studies 430

17.8 Testing Considerations 431

17.8.1 Test Methodology in Our Laboratory 432

17.9 Discussion 435

References 435

18. Radioactive Aerosols: Tracers of Atmospheric Processes 441
Katsumi Hirose

18.1 Introduction 441

18.2 Origin of Radioactive Aerosols 442

18.2.1 Natural Radionuclides 442

18.2.2 Anthropogenic Radionuclides 444

18.3 Tracers of Atmospheric Processes 446

18.3.1 Transport of Radioactive Aerosols 446

18.3.2 Dry Deposition 448

18.3.3 Wet Deposition 449

18.3.4 Resuspension 450

18.3.5 Other Processes 452

18.3.6 Application of Multitracers 452

18.3.7 Atmospheric Residence Time of Radioactive Aerosols 454

18.4 Tracer of Environmental Change 457

18.5 Conclusion 460

References 461

Index 469

IAN COLBECK, University of Essex, UK

MIHALIS LAZARIDIS, Technical University of Crete, Greece