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THE INVESTIGATION OF ATMOSPHERIC POLLUTION.
(* Summary of a Paper read at the Ninth International Congress of Pure and Applied
Chemistry, Madrid, April, 1934.)
By J. H. Coste, F.I.C., F.Inst.P., Member of the Atmospheric Pollution Research
Committee of the Department of Scientific and Industrial Research; Chemist,
London County Council.
The products of the combustion of fuel and of industrial operations which
constitute atmospheric pollution are emitted either as gases and vapours, which
mix freely with the air, or as aggregates ranging in dimensions from condensation
nuclei of diameters of the order of 4.5 X 10-6 cm. to particles of coke and ash which
are so large as to fall to the ground near their source.
Gases and vapours thus emitted become so diluted that the classic gas volumetric
methods are useless, and ad hoc methods in which large volumes of air are
brought in contact with suitable reagents are used. Trustworthy processes for
carbon dioxide and monoxide, sulphur dioxide, oxides of nitrogen and the vapours
of many organic substances are available.
The finer dispersions of liquids and solids, which are kept in the air by
Brownian movement, are difficult to capture. Methods based on thermal, electrical
and mechanical separation, the effective masses of the particles often being increased
by the adiabatic deposition of water, have proved useful. Filters have also
given valuable results.
Larger particles may be collected by allowing them to fall under the influence
of gravity, on suitable surfaces.
The amounts of impurity found may be expressed as the mass or volume in
a specified volume of air, or as the quantity deposited on a specified area of land
or of an absorbing surface. The relation between results expressed in these two
ways is obscure, but each has its advantages, according to the object of the investigation.
Organisation of general and special investigations and the treatment of results
are discussed and actual results of investigations are given.
* The full paper will appear in due course in the proceedings of the Congress.
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