Page 57 - Fundamentals of Air Pollution

Questions 33

of this chapter. When does air pollution exist? This chapter presents some
of the principles by which materials may be introduced into the atmosphere,
moved about, and removed from the atmosphere. The definition of air
pollutant or air pollution depends on the context of time, space, and impact
for a particular set of circumstances. Smoke in a cave was a major problem
for early humans but not one we consider today. Indoor air quality or
pollution in our homes and workplaces are concerns of today. Elevated
levels of ozone, organic gases, and other trace gases in our communities
are the "air pollution" problems of today. Governments around the world
have established and are continously evaluating the impact of elevated
levels of trace gases and particulate material in the atmosphere. This process
helps bring meaning to the definitions offered at the beginning of the
chapter—"to defile, to make impure" the atmosphere.

REFERENCES

Turner, D. B. Meteorological fundamentals, in "Meteorological Aspects of Air Pollu-
tion—Course Manual. Air Pollution Training Institute, Office of Manpower Development,
Office of Air Programs. United States Environmental Protection Agency, Research Triangle
Park, NC,
Lapple, C. E., Stanford Research Inst. J. 5, 95 (1961).

SUGGESTED READING

Bridgman, H. A,, "Global Air Pollution: Problems for the 1990's." Belhaven, London, 1990.
Graedel, T. E., and Crutzen, P. J., "Atmospheric Change: An Earth System Perspective."
W.H. Freeman, New York, 1993.
Seinfeld, J. H., "Atmospheric Chemistry and Physics of Air Pollution," Wiley, New York,
1986.
Warneck, P., "Chemistry of the Natural Atmosphere." Academic Press, San Diego, 1988.

QUESTIONS

3
1. Prepare a graph showing the conversion factor from ppm (vol) to ;ug/m for compounds
with molecular weights ranging from 10 to 200 at 25°C and 760 mm Hg as well as at 0°C
and 760 mm Hg.
3
2. (a) Convert 0.2 ppm (vol) NO and 0.15 ppm (vol) NO 2 to jug/m nitrogen oxides (NO X) at
3
25°C and 760 mm Hg. (b) Convert 0.35 ppm (vol) NO X to fig/m at 25°C and 760 mm Hg.
3
3. Prepare a table showing the weight in grams and the surface area in m of a 0.1-, 1.0-,
10.0-, and 100.0-/xm-diameter spherical particle of unit density.
4. What is the settling velocity in cm/sec in air at 25°C and 1 atmosphere for a 100 mesh size
spherical particle, i.e., one which just passes through the opening in the sieve (specific
gravity = 2.0)?