Pollution

Dead and decaying remains of plants, Animal excreta, Waste papers, Domestic refuge

Biodegradable pollutants are substances that can be decomposed into harmless constituents by biological activities of microbes. These include organic matter like plant remains, animal excreta, waste papers, and domestic refuse. Plastics and pesticides are non-biodegradable.

Carbon dioxide, Methane, CFCs, Nitrogen oxides

Greenhouse gases include CO₂, CFCs, methane, and nitrogen oxides. These gases allow solar radiation to reach Earth but prevent heat from escaping, causing global warming. They behave like glass windows of a greenhouse.

Chlorofluorocarbons (CFCs)

The ozone hole is mainly caused by CFCs (chlorofluorocarbons) used in refrigerators and air conditioners. CFCs react with ozone (O₃) and decompose it, resulting in thinning of the protective ozone layer.

Vehicle exhausts, Industrial emissions, Burning of fossil fuels, Use of pesticides

Major sources of air pollution include vehicle exhausts, industrial emissions, burning of fossil fuels, and pesticide spraying. These release harmful gases and particles into the atmosphere. Photosynthesis and plant respiration are natural processes that don't cause pollution.