Indoor Aerosol Dynamics

TENGFEI (TIM) ZHANG is a Professor at Dalian University of Technology and Adjunct Professor at Tianjin University. He holds degrees from Purdue University, Tsinghua University, and Southeast University. As a recognized expert in his field, he has received numerous awards and serves as an editor of the journal of Building and Environment. Dr. Zhang has led major national and international research projects and chaired the Healthy Buildings 2023 Asia-Pacific Conference. FEI LIU is an Assistant Professor at Qingdao University of Technology. He received his PhD from Tianjin University and conducted visiting research at KTH. His research interests cover building ventilation and indoor air quality. Dr. Liu has published multiple papers in high-impact journals. He is a member of the International Society of Energy and Built Environment (ISEBE).

• Preface xiiiList of Abbreviations xviiNomenclature xxiAbout the Companion Website xxix1 Aerosol Fundamentals 11.1 Introduction 11.2 Definitions of Aerosols 11.3 Sources of Aerosols 11.3.1 Natural Aerosol Sources 21.3.2 Anthropogenic Aerosol Sources 21.3.3 Secondary Aerosols 31.4 Physical Properties of Aerosol Particles 41.4.1 Particle Size 41.4.2 Particle Density 51.4.3 Particle Shape 61.4.4 Particle Surface Area 71.4.5 Particle Concentration 81.4.6 Electrical Properties of Aerosol Particles 91.5 Chemical Properties 101.6 Bioaerosol 101.6.1 Definition 111.6.2 Sources of Bioaerosols 121.7 Size Distribution of Aerosol Particles 121.7.1 Overview of Particle Sizes 121.7.2 Particle Size Distribution Functions 131.7.2.1 Normal Distribution 131.7.2.2 Lognormal Distribution 141.8 Summary 16Problems 17References 172 Particle Motion Basics 212.1 Introduction 212.2 Newton’s Resistance Law 212.3 Stokes’s Law 232.4 Settling Velocity 252.5 Particle Mobility 252.6 Slip Correction Factor 262.7 Nonspherical Shape Correction 302.8 Aerodynamic Diameter 312.9 Correction to Stokes’s Law near Boundary Walls 322.10 Summary 34Problems 35A. Appendix: Derivation of Stokes’s Law 36References 393 Straight-Line Acceleration and Curvilinear Particle Motion 413.1 Introduction 413.2 Relaxation Time 413.3 Straight-Line Particle Acceleration 433.4 Stopping Distance 463.5 Curvilinear Motion 483.6 Stokes Number 493.7 Inertial Impaction 503.8 Summary 55Problems 56References 574 Adhesion and Detachment of Particles 594.1 Introduction 594.2 Adhesive Forces 594.2.1 van der Waals Force 594.2.2 Electrostatic Force 614.2.3 Surface Tension Force 614.2.4 Overall Adhesive Forces and Some Comparisons 624.3 Detachment of Particles 644.3.1 Methods for Measurement of Particle Detachment 644.3.1.1 Centrifugal Separation 644.3.1.2 Air Blowing for Particle Separation 644.3.1.3 Atomic Force Microscopy Separation 664.3.1.4 Vibration Separation 674.3.2 Comparison of Forces Acting on Particles 684.4 Particle Resuspension 694.4.1 Major Factors Affecting Particle Resuspension 694.4.1.1 Aerodynamic Action 704.4.1.2 Mechanical Disturbances 714.4.1.3 Electrostatic Action 734.4.1.4 Surface Properties 734.4.1.5 Particle Properties 734.4.2 Resuspension in Boundary Layers 734.4.3 Particle Resuspension Rates 744.5 Particle Bounce 764.6 Summary 77Problems 78References 795 Brownian Motion and Diffusion and Thermophoresis 815.1 Introduction 815.2 Diffusion Coefficient 815.3 Particle Mean Thermal Velocity 855.4 Particle Mean Free Path 865.5 Brownian Displacement 875.6 Diffusion Deposition 895.7 Thermophoresis 925.8 Summary 96Problems 96References 976 Sampling and Measurement of Particle Concentrations 996.1 Introduction 996.2 Particle Sampling 996.2.1 Isokinetic Sampling 1006.2.2 Anisokinetic Sampling 1026.2.2.1 Misalignment Sampling 1026.2.2.2 Superisokinetic Sampling 1046.2.2.3 Subisokinetic Sampling 1056.3 Sampling from Still Air 1066.4 Particle Transport Losses 1086.4.1 Diffusion Deposition Loss 1096.4.2 Inertial Deposition Loss 1106.4.3 Electrostatic and Thermophoretic Deposition Loss 1116.5 Off-Line Measurement of Particles 1116.5.1 Filter Sampling 1126.5.2 Inertial Classifier 1136.6 Real-Time Measurement of Particles 1156.6.1 Semi-Continuous Mass Measurement 1156.6.2 Optical Measurement 1166.6.2.1 Optical Particle Counter 1166.6.2.2 Condensation Particle Counter 1186.6.2.3 Fluorescence-based Bioaerosol Detection 1186.7 Summary 120Problems 121References 1227 Indoor Aerosol Sources 1257.1 Introduction 1257.2 Aerosol Sources in Households 1257.2.1 Cooking Oil Fumes 1257.2.1.1 Chemical Compounds in COFs 1267.2.1.2 Emission Dynamics of COFs 1267.2.2 Particle Emission from Heat Sources 1287.2.2.1 Cooking Heat Sources 1287.2.2.2 Building Heat Sources 1307.2.3 Cigarette Smoke Aerosols 1307.2.4 Incense Stick and Candle Burning Aerosols 1327.2.5 Ironing Aerosols 1337.2.6 Secondary Organic Aerosols (SOAs) 1337.2.6.1 Formation of SOAs 1337.2.6.2 Spraying of Household Cleaning Products or Liquid Air Fresheners 1347.2.6.3 Personal Care Products Usage 1367.3 Aerosol Sources in Offices 1377.3.1 From Printers 1377.3.2 From Photocopiers 1387.3.3 From Computers 1407.4 Aerosol Sources in Lavatories 1407.4.1 Aerosol Emission from Toilet Flushing 1417.4.1.1 Surveyed Bioaerosol Emission after Flushing of a Toilet 1417.4.1.2 Flushing a Sitting Toilet 1437.4.1.3 Flushing a Squatting Toilet 1447.4.1.4 Flushing a Vacuum Toilet 1447.4.2 Aerosol Emission from Urinal Flushing 1447.4.3 Aerosol Emission from Handwashing 1467.4.4 Aerosol Emission during Hand Drying under a Jet Dryer 1477.4.5 Aerosol Emission from Showering 1507.5 Intrusion of Outdoor Particles 1517.5.1 Intrusion of General Outdoor Particles 1517.5.1.1 Mechanical Ventilation Pathway 1517.5.1.2 Natural Ventilation Pathway 1527.5.1.3 Penetration Through Building Cracks 1537.5.1.4 Indoor/Outdoor Particle Concentration Ratio (I/O ratio) 1547.5.2 Intrusion of Pollens and Molds 1577.5.2.1 Intrusion of Pollens 1577.5.2.2 Intrusion of Molds 1587.6 Summary 1627.6.1 In Households 1637.6.2 In Offices 1637.6.3 In Lavatories 1637.6.4 Intrusion of Outdoor Aerosols 164Problems 165References 1668 Indoor Aerosol Transport Modeling 1798.1 Introduction 1798.2 Multizone Model 1798.2.1 Basic Principles 1798.2.2 Demonstration of Multizone Modeling of Airflow and Transport of a Tracer Gas inside a House 1828.2.3 Demonstration of Multizone Modeling of Particle Transport and CO 2 Concentration in a Test Room 1848.3 CFD Modeling of Air Motion 1878.3.1 Governing Equations of RANS Modeling 1878.3.2 Numerical Solution to the RANS Model 1888.3.3 Demonstration of CFD Modeling of Airflow, Heat Transfer, and Transport of a Tracer Gas in Indoor Environments 1928.4 Eulerian-Based Particle Modeling 1988.4.1 Basic Principles 1988.4.2 Demonstration of Eulerian-Based Particle Modeling in a Ventilated Enclosure 1998.5 Lagrangian-Based Particle Modeling 2028.5.1 Basic Principles 2028.5.2 Demonstration of Lagrangian-Based Particle Modeling in a Ventilated Enclosure 2048.6 Multiphase Particle Modeling 2078.6.1 Basic Principles 2078.6.1.1 Multiphase Flow Modeling 2078.6.1.2 Coupled Euler–Lagrange Modeling 2088.6.1.3 Heat and Mass Transfer Modeling 2108.6.2 Demonstration of Modeling of Cough Droplets in Space 2128.6.3 Demonstration of Modeling of Liquid Aerosol Generation and Transport during the Flushing of a Squat Toilet 2148.7 Summary 219Problems 220References 2229 Indoor Aerosol Exposure and Health Effects 2259.1 Introduction 2259.2 Mechanisms of Respiratory Exposure 2259.3 Mechanisms of Toxicity of Aerosol Components 2299.4 Health Effects of Nonbiological Aerosol Exposure 2319.4.1 Birth Outcomes 2329.4.2 Mortality 2329.4.3 Atopic Allergy and Asthma 2329.4.4 Cancer 2339.4.5 Cardiovascular Problems 2339.5 Health Effects of Noninfectious Bioaerosol Exposure 2349.5.1 Asthma 2349.5.2 Rhinitis 2359.5.3 Chronic Airflow Obstruction 2359.5.4 Hypersensitivity Pneumonitis 2359.5.5 Chronic Bronchitis 2359.5.6 Pulmonary Hemorrhage 2369.5.7 Organic Dust Toxic Syndrome (ODTS) 2369.5.8 Cancer 2369.5.9 Building-related Illnesses and Symptoms 2369.6 Summary 237Problems 237References 23810 Indoor Pathogenic Aerosols and Transmission of Infection 24110.1 Introduction 24110.2 Shedding of Pathogenic Aerosols 24110.2.1 Brief Introduction 24110.2.2 Shedding of Liquid Aerosols by Breathing 24210.2.3 Shedding of Liquid Aerosols by Talking 24410.2.4 Shedding of Liquid Aerosols by Coughing and Sneezing 24510.3 Transmission of Pathogenic Aerosols 24710.3.1 Brief Introduction 24710.3.2 Droplet Transmission 24810.3.3 Airborne Transmission 25010.3.4 Contact Transmission 25210.4 Infectious Dose and Infection Risk 25310.4.1 Brief Introduction 25310.4.2 Minimum Dose for Infection 25310.4.3 Wells–Riley Model 25410.4.4 Demonstration of the Wells–Riley Model in a Classroom 25610.4.5 Dose–Response Model 26010.4.6 Demonstration of the Dose–Response Model in an Aircraft Cabin 26210.5 Summary 264Problems 265References 26611 Particle Filtration and Indoor Air Cleaning 27111.1 Introduction 27111.2 Fiber Filters 27111.2.1 Filtration Mechanisms 27111.2.1.1 Interception 27111.2.1.2 Inertial Impaction 27311.2.1.3 Diffusion 27411.2.1.4 Gravitational Settling 27511.2.1.5 Electrostatic Attraction 27611.2.2 Performance Evaluation of Fiber Filters 27611.2.2.1 Face Velocity and Filtration Velocity 27611.2.2.2 Efficiency and Penetration Ratio 27711.2.2.3 Pressure Drop 27911.2.2.4 Quality Factor 28011.2.2.5 Dust-holding Capacity 28011.3 Electrostatic Precipitator 28111.3.1 Basic Principles of ESPs 28111.3.2 Evaluation of ESP Performance 28311.3.2.1 Electric Field 28311.3.2.2 Particle Migration Velocity 28311.3.2.3 Particle Collection Efficiency 28411.4 Operation of Air Cleaners 28411.4.1 PM Exposure Limits 28411.4.2 Air Cleaner Operation 28611.4.2.1 Clean Air Delivery Rate (CADR) 28611.4.2.2 Operation of Air Cleaners and Replacement of Air Filters 28711.5 Summary 287Problems 288References 28912 Inactivation of Indoor Microbial Aerosols 29112.1 Introduction 29112.2 Chemical Disinfectants 29112.2.1 Alcohol-Based Disinfectants 29212.2.2 Quaternary Ammonium Compounds 29212.2.3 Chlorine Compounds 29312.2.4 Hydrogen Peroxide 29412.3 Ultraviolet Germicidal Irradiation (UVGI) 29512.3.1 Mechanism of UVC Inactivation of Microbes 29512.3.2 UVC Light Sources 29512.3.2.1 Mercury-Vapor Lamps 29612.3.2.2 Light-Emitting Diodes (LEDs) 29612.3.2.3 Excimer Lamps 29712.3.3 Factors Affecting UVC Inactivation Performance 29712.3.3.1 Microbial Species 29712.3.3.2 Environmental Conditions 29712.3.3.3 Medium of Microbial Attachment 29712.3.4 Environmental and Health Safety Issues 29812.4 Plasma Treatment 29912.4.1 Mechanisms of Plasma Treatment 29912.4.1.1 Etching Effect on the Cell 30012.4.1.2 Cell Membrane Perforation and Electrostatic Disruption 30012.4.1.3 Oxidation of Intracellular Macromolecules 30112.4.2 Effectiveness of Plasma Treatment 30112.5 Other Disinfection Technologies 30312.5.1 Ozone Oxidation 30312.5.2 Photocatalytic Oxidation (PCO) 30412.6 Summary 305Problems 305References 306Appendices 311Index 325