Smog is an immovable blanket of poisoned air settling over a locality and causing an epidemic outbreak of acute respiratory illness, resembling pneumonia, among the population.
Such outbreaks result in many deaths and in even many more cases of permanent invalidism.Smog pollution of the air occurs mostly in low level land in valley areas having mines and metal manufacturing plants, which contaminate the air by gases, smoke , and dust.
The poison in the air consist mostly of carbon monoxide, sulphur dioxide , sulphur trioxide , soft coal smoke, coal dust, soot and metallic dust.
Localities with strong air currents are not easily contaminated by these waste materials.
Under normal atmospheric conditions the air near the ground is warmer than the upper strata, and the tendency of warm air to rise creates constant air currents, which disperse poisons.
But sometimes a cold layer of air laden with fog and smoke will stay immovably close to the ground and thus retaining all the poisonous material emitted from mines and metal factories and poisoning the population of that area.
Factories producing Beryllium, Zinc, Copper and Lead are particularly poison producing. The smog of one zinc plant has caused twenty deaths.
The smog over Donora, Pa.Recently has caused illness in 75 % of all persons over fifty years of age and of 50 % of persons under fifty years of age, of a population of about fifteen thousand.
There ware about 50 deaths traceable directly to the smog.
People suffering with heart disease, asthma and other lung diseases are most dangerously affected by this air pollution.
Unquestionably , if our engineering fraternity and government agencies, such as the federal Public Health Service, were to put their heads together, methods of preventing air pollution would readily be devised