Tropospheric pollution occurs due to the presence of undesirable solid or gaseous particles in the air. ... Gaseous air pollutants: These are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.

Tropospheric pollution is primarily caused by various oxides of sulphur, nitrogen, carbon, and halogens. Let's break down this answer in detail:

1. Definition of Tropospheric Pollution:
The troposphere is the lowest layer of the Earth's atmosphere, extending from the Earth's surface up to approximately 10 kilometers. Tropospheric pollution refers to the contamination of this layer with harmful pollutants, leading to adverse effects on human health, ecosystems, and the environment.

2. Causes of Tropospheric Pollution:
The major contributors to tropospheric pollution are the various oxides of sulphur, nitrogen, carbon, and halogens. These pollutants are released into the atmosphere through human activities such as industrial processes, burning of fossil fuels, vehicular emissions, and agricultural practices.

3. Sulphur Oxides:
Sulphur oxides, including sulphur dioxide (SO2) and sulphur trioxide (SO3), are released into the atmosphere primarily from the burning of fossil fuels like coal and oil. Industrial processes such as smelting, refining, and power generation also contribute to sulphur oxide emissions. These pollutants can lead to respiratory problems, acid rain formation, and damage to vegetation.

4. Nitrogen Oxides:
Nitrogen oxides (NOx), including nitric oxide (NO) and nitrogen dioxide (NO2), are released into the atmosphere from the burning of fossil fuels, especially in vehicles and power plants. Industrial processes and agricultural activities also contribute to nitrogen oxide emissions. These pollutants can cause respiratory issues, smog formation, and contribute to the formation of acid rain.

5. Carbon Oxides:
Carbon oxides, particularly carbon monoxide (CO) and carbon dioxide (CO2), are released into the atmosphere through the incomplete combustion of fossil fuels. Motor vehicles, industrial processes, and deforestation are major sources of carbon oxide emissions. Carbon monoxide is a poisonous gas, while carbon dioxide is a greenhouse gas responsible for climate change.

6. Halogens:
Halogens, including chlorine (Cl) and bromine (Br), are released into the atmosphere through human activities such as the use of chlorofluorocarbons (CFCs), which were commonly used in refrigeration, air conditioning, and aerosol propellants. These pollutants can deplete the ozone layer, leading to increased ultraviolet (UV) radiation reaching the Earth's surface.

In conclusion, tropospheric pollution is primarily caused by various oxides of sulphur, nitrogen, carbon, and halogens. These pollutants are released into the atmosphere through human activities and can have detrimental effects on human health, ecosystems, and the environment.