Encyclopedia of Environmental Science and Engineering, Volume I and II

59

AIR POLLUTION METEOROLOGY

EFFECTS OF WEATHER ON POLLUTION

Introduction

As the world’s population and industrialization grow, air

pollution (Figure 1) becomes a progressively more serious

problem. The control of air pollution requires the involve-

ment of scientists from many disciplines: physics, chemistry

and mechanical engineering, meteorology, economics, and

politics. The amount of control necessary depends on the

results of medical and biological studies.

The state of the atmosphere affects, first, many types of pol-

lution. For example, on a cold day, more fuel is used for space

heating. Also, solar radiation, which is affected by cloudiness,

has an influence as smog production. Second, atmospheric

conditions determine the behavior of pollutants after they leave

the source or sources until they reach receptors, such as people,

animals, or plants. The question to be answered is: given the

meteorological conditions, and the characteristics of the source

or sources, what will be the concentration of the pollutants at

any distance from the sources? The inverse question also is

important for some applications: given a region of polluted air,

where does the pollution originate?

Finally, the effect of the pollution on the receptor may

depend on atmospheric conditions. For example, on a humid

day, sulfur dioxide is more corrosive than on a dry day.

Meteorological information is needed in three general

areas of air pollution control:

(1) In planning control measures, wind climatology

is required. Pollution usually must be reduced

to a point where the air quality is substantially

better than the existing quality. In order to assure

improved quality, certain standards are set which

prescribe maximum concentrations of certain

pollutants.

In order to reach such standards, the points of origin of

the pollution must first be located; traditionally, everybody

blames everybody else for the unsatisfactory air quality.

Given possible pollution sources, tracing of air trajectories

coupled with estimates of atmospheric dispersion will give

the required answers. Once the relative importance of differ-

ent pollution sources is known, strategies have to be devel-

oped to determine the degree to which each source must

reduce its effluent.

The most economical way to cut concentration of some

pollutant may not be to cut the effluent of each emitter by the

same amount. In order to find the best strategy, city models

must be constructed, separately for each pollutant and for

different meteorological conditions, which show how the air

pollution climate of an urban region is affected by the exist-

ing distribution of sources, and what change would be pro-

duced when certain sources are controlled. The construction

of such models will be discussed later, and requires a fairly

sophisticated handling of meteorological data. The same

models then also help in planning future growth of housing

and industry.

Of course, not all problems of air pollution meteorology

are as complex as those involving urban areas. The planning

of individual plants, for example, must be based in part on

the air pollution to be expected from the plant under various

atmospheric conditions; meteorological calculations may

show whether expensive techniques for cleaning the effluent

before leaving the stack may be required.

(2) Meteorological forecasts can be used to vary

the effluent from day to day, or even within a

24 hour period. This is because at different times

the atmosphere is able to disperse contaminants

much better than at other times; purer fuels must

be used, and operation of certain industries must

be stopped completely in certain areas when the

FIGURE 1 Air pollution in New York City prior to SO 2 and

particulate restriction.

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