Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgments
- 1 BASICS AND HISTORY OF DISCOVERY OF ATMOSPHERIC CHEMICALS
- 2 THE SUN, THE EARTH, AND THE EVOLUTION OF THE EARTH'S ATMOSPHERE
- 3 STRUCTURE AND COMPOSITION OF THE PRESENT-DAY ATMOSPHERE
- 4 URBAN AIR POLLUTION
- 5 AEROSOL PARTICLES IN SMOG AND THE GLOBAL ENVIRONMENT
- 6 EFFECTS OF METEOROLOGY ON AIR POLLUTION
- 7 EFFECTS OF POLLUTION ON VISIBILITY, ULTRAVIOLET RADIATION, AND ATMOSPHERIC OPTICS
- 8 INTERNATIONAL REGULATION OF URBAN SMOG SINCE THE 1940s
- 9 INDOOR AIR POLLUTION
- 10 ACID DEPOSITION
- 11 GLOBAL STRATOSPHERIC OZONE REDUCTION
- 12 THE GREENHOUSE EFFECT AND GLOBAL WARMING
- Appendix: Conversions and Constants
- References
- Photograph Sources
- Index
5 - AEROSOL PARTICLES IN SMOG AND THE GLOBAL ENVIRONMENT
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Acknowledgments
- 1 BASICS AND HISTORY OF DISCOVERY OF ATMOSPHERIC CHEMICALS
- 2 THE SUN, THE EARTH, AND THE EVOLUTION OF THE EARTH'S ATMOSPHERE
- 3 STRUCTURE AND COMPOSITION OF THE PRESENT-DAY ATMOSPHERE
- 4 URBAN AIR POLLUTION
- 5 AEROSOL PARTICLES IN SMOG AND THE GLOBAL ENVIRONMENT
- 6 EFFECTS OF METEOROLOGY ON AIR POLLUTION
- 7 EFFECTS OF POLLUTION ON VISIBILITY, ULTRAVIOLET RADIATION, AND ATMOSPHERIC OPTICS
- 8 INTERNATIONAL REGULATION OF URBAN SMOG SINCE THE 1940s
- 9 INDOOR AIR POLLUTION
- 10 ACID DEPOSITION
- 11 GLOBAL STRATOSPHERIC OZONE REDUCTION
- 12 THE GREENHOUSE EFFECT AND GLOBAL WARMING
- Appendix: Conversions and Constants
- References
- Photograph Sources
- Index
Summary
Although most regulations of air pollution focus on gases, aerosol particles cause more visibility degradation and possibly more health problems than do gases. Particles smaller than 2.5 μm in diameter cause the most severe health problems. Particles enter the atmosphere by emissions and nucleation. In the air, their number concentrations and sizes change by coagulation, condensation, chemistry, water uptake, rainout, sedimentation, dry deposition, and transport. Particle concentration, size, and morphology affect the radiative energy balance in urban air and in the global atmosphere. In this chapter, compositions, concentrations, sources, transformation processes, sinks, and health effects of aerosol particles are discussed. The effects of aerosol particles on visibility are described in Chapter 7. Regulations relating to particles are given in Chapter 8.
SIZE DISTRIBUTIONS
Aerosol and hydrometeor particles are characterized by their size distribution and composition. A size distribution is the variation of concentration (i.e., number, surface area, volume, or mass of particles per unit volume of air) with size. Table 5.1 compares typical diameters, number concentrations, and mass concentrations of gases, aerosol particles, and hydrometeor particles under lower tropospheric conditions. The table indicates that the number and mass concentrations of gas molecules are much greater than are those of particles. The number concentration of aerosol particles decreases with increasing particle size. The number concentrations of hydrometeor particles are typically less than are those of aerosol particles, but the mass concentrations of hydrometeor particles are always greater than are those of aerosol particles.
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- Atmospheric PollutionHistory, Science, and Regulation, pp. 115 - 144Publisher: Cambridge University PressPrint publication year: 2002