수정본

Firstly, it is obvious that at the root of any environmental problem, including the lack of clean air, is the irrational usage and consumption of natural resources by mankind.

Moreover, the modern society factors such as global industrialization, an increase in the number of transport vehicles using internal combustion engines and a steady increase of the population, accelerate this process in a geometric progression.

Satisfying the need of a growing humanity in food and building materials, people continue to cut down forests - the main sources of oxygen, which also directly affects the quality of the inhaled air, the shortage of which is acute in megacities.

For example, according to recent studies, air in cities with a population of more than one million inhabitants over the past 10 years has become 21% more polluted than before.