Air Pollution – Types, Sources and Effects

Posted on Oct 10 2019 - 9:36am by Preeti

2. Secondary Pollutants
Secondary pollutants are formed by primary pollutants their reaction with normal atmospheric compounds. Ozone is a secondary pollutant formed by photochemical reaction between primary pollutants and natural atmospheric gas. Ozone affects the respiratory and nervous system. It also damages rubber products and textiles. PAN, a secondary pollutant is formed when hydrocarbon radicals react with nitrogen dioxide. Peroxy Acetyl Nitrate causes photochemical smog and also causes irritation of the eyes, nose, throat and respiratory distress. Disposition of the toxic secondary pollutants, either in gaseous form or as particulates on soil make the soil unsuitable for plant growth. Acid rain for longer period decreases the pH of the soil and makes it acidic. Particulates on the other hand, deposit on the leaves of plants and block their stomata. As a result the rate of photosynthesis and transportation decreases and leads to decreased crop yield and retarded growth. Cattle are also found to be affected by air pollution. Ozone and PAN irritates the eyes, impair vision and create breathing problems leading to asthma in human beings.

Common Air pollutants, their sources and effects of human beings



Pathological effect on human beings


Thermal decomposition of oils, fats and glycerols. Irritates nasal and respiratory tracts.


Explosives, dye-making, fertilizer plants and lacquers. Inflames upper respiratory passage.


Process involving metal or acid containing arsenic soldering Damages red blood cells, kidneys and causes jaundice.

Carbon monoxide

Burning of coal, gasoline motor exhaust. Reduces oxygen carrying capacity of blood.

Hydrogen cyanides

Blast furnance, fumigation, chemical plants. Interferes with nerve cells, produces dry throat, indistinct vision, headache.

Hydrogen sulphide

Refineries, chemical industries and bituminous fuels. Causes nausea, irritation of eyes and throat.

Nitrogen oxide

Soft coal, automobile exhaust. Inhibits cilia action so that soot and dust penetrated far into the lungs.


Chemical and dye-making industry. Induces coughing, irritation and fatal pulmonary oedema.

Sulphur dioxide

Combustion of coal and oil. Causes chest constriction, headache, vomiting and ultimately, death due to respiratory ailments.

Suspended particles (ash, soot, smoke, etc. )

Incinerator and almost every manufacturing process. Causes emphysema, irritation in the eyes and possibly, cancer.
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