Tropospheric pollution arises due to the presence of undesirable substances in the lowest layer of the atmosphere. Tropospheric air pollution has impacts on scales ranging from local to global. Reactive intermediates in the oxidation of mixtures of volatile organic compounds (VOCs) and oxides of nitrogen (NOx) play central roles: the hydroxyl radical (OH), during the day; the nitrate radical (NO₃), at night; and ozone (O₃), which contributes during the day and night. Oxides of sulphur, nitrogen, carbon, and hydrocarbons are the major gaseous pollutants.

Oxides of sulphur (SO₂ and SO₃) and nitrogen (NO₂, NO) are produced as a result of the burning of fossil fuels (coal, automobile fuel). These oxides react with water in the presence of atmospheric oxygen to form nitric acid (HNO₃) and sulphuric acid (H₂SO₄), which leads to the formation of ‘Acid rain’. Acid rain causes harm to agriculture, plants, and trees. It also leads to various respiratory

ailments.

The effects of tropospheric pollution are:

1) They cause respiratory disease like asthma, bronchitis, irritation & redness in the eyes. Increase in levels of carbon monoxide leads to a headache, nervousness and cardiovascular diseases.

2) Increase in Carbon dioxide level leads to global warming and can disturb the balance in the atmosphere.

The particulate pollutants lead to the development of photo chemical smog and act as eye irritants. They also irritate nose and throat and causes chest pain, dryness of throat and cough etc.

The effect of pollution is showing its ill-effects in major cities where pollution is on the high. In the capital city, Delhi, even though measures are taken it has become difficult to bring the pollution levels down. Sustainable development and use of green chemistry can further help in resolving these issues to an extent.