Page 232 - Fundamentals of Air Pollution

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Ambient Air Pollutants:

Analysis and Measurement

I. ANALYSIS AND MEASUREMENT OF GASEOUS POLLUTANTS

The two major goals of testing for air pollutants are identification and
quantification of a sample of ambient air. Air pollution measurement tech-
niques generally pass through evolutionary stages. The first is the qualita-
tive identification stage. This is followed by separate collection and quanti-
fication stages. The last stage is the concurrent collection and quantification
of a given pollutant.
Gaseous SO 2 is an example. Very early procedures detected the presence
of SO 2 in ambient air by exposing a lead peroxide candle for a period of
time and then measuring the amount of lead sulfate formed. Because the
volume of air in contact with the candle was not measured, the technique
could not quantify the amount of SO 2 per unit volume of air.
The next stage involved passing a known volume of ambient air through
an absorbing solution in a container in the field and then returning this
container to the laboratory for a quantitative determination of the amount of
absorbed SO 2. The United Nations Environmental Program-World Health
Organization's worldwide air sampling and analysis network used this
method for SO 2/ the only gaseous pollutant measured by the network. The

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