The pollutants of air are numerous and this is as a result of byproducts of an advanced technological society. As long as man has lived in cities, he has and will continue to pollute the air. Major cities around the globe must now strive to deal with dangerously rising levels of air pollution. With the advent of population migration and growth; urbanization, which is the agglomeration of people in space, the rate of the acquisition of automobiles for instance, has quadrupled over the past century, that is from the 1950’s up till now. And as such, the rate of air pollution has also quadrupled.
Noted also, smog from these cities in recent times especially before the Covid-19 pandemic, drifted into many sub-urban and rural areas where it has been fed by cars, incinerators, and heating and generating plants.
Urban air pollution was once considered a problem of merely smoke in the air and the main source of the smoke obviously was industry which burned great quantities of coal, oil and other fossil fuels.
The word “smog” was coined and was generally assumed to simply denote a mixture of smoke and fog. There’s however, a chemical explanation for the smog problem because cities which do not have heavy industrial complexes like burning coal or oil have had to deal with severe smog problem. Certain compounds that are present in car exhaust emissions-gaseous hydrocarbons and oxides of nitrogen- are invisible as they enter the atmosphere. Once in the air, however, they react under the influence of sunlight to form the ingredients of photochemical smog, a noxious form of pollution that brings tears to our eyes and makes us cough and choke as we breathe it. The combination of large numbers of cars and local weather conditions make cities like Los Angeles, California and China particularly subject to photochemical smog. But cars are a major source of air pollution all around the world.
For instance, photochemical smog put Mexico City on the list of the world’s most polluted cities. Cars, buses and trucks, account for sixty percent of the ongoing air pollution with carbon emissions somewhat exceeding those of Los Angeles. In Sidney, Australia which was once believed to be the cleanest environment at a time, has since been plagued with a high percentage of automobile emissions in the air, higher than that of any city in the United States.
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