Pollutants in the air can create smog and acid rain, cause respiratory or other serious health illnesses, damage the protective ozone layer in the upper atmosphere, contribute to climate change.

Polluting substances - sulphur dioxide and nitrogen oxides emissions emitted from stationary and mobile sources can cause very harmful process - acidification. SO₂, NO_x emitted into the atmosphere can be oxidised into sulphuric acid and nitric acid and to cause acid rain. Acid rain can affect surface waters, soil, vegetation and also damaged wood, stone and metal in buildings, monument and water pipes. Decrease of acid precipitation can cause defoliation and reduced vitality of trees, declining fish stocks and decreased diversity of other aquatic animals in acid - sensitive lakes, rivers and streams, and changes in soil chemistry.

After the year 1989, turnover in the air quality development occurred in Slovakia. The first phase of the Slovak economy transformation process from the centrally planned to the market economy was followed with sufficient fall of the industrial production in Slovakia (by approximately 30 %). In term of air pollution, the sufficient fall of energy consumption and military industry attenuation occurred. An ineffective metallurgy production (nickel, mercury production, iron ore treatment) stopped as well. In 1991, the Clean Air Act (309/1991 Col.) was accepted together with several actual laws and regulations concerning the air protection. In 1993, the announcement on compulsory use of the three way catalytical converter for all the new and imported older cars entered into force. The lead gasoline is not currently produced and marketed in the Slovak Republic. Consecutive liberalisation of fuel and energy prices is becoming the important economic tool of air quality protection.