Environmental pollution

The essentials

Environmental pollution results from the release of substances and energy from human activities into the environment. It is classified as air, water, land and noise pollution according to the medium through which pollutants spread.

Water pollution comes from industrial effluents, domestic sewage, urban runoff and agricultural chemicals such as fertilisers and pesticides. Polluted water spreads diseases like diarrhoea, intestinal worms and hepatitis. Stretches of the Ganga near large cities such as Kanpur and Varanasi, and the Yamuna between Delhi and Etawah, are badly polluted.

Air pollution is the addition of harmful substances such as sulphur dioxide, nitrogen oxides, carbon monoxide, hydrocarbons, lead and particulate matter into the air. Sources include burning of fossil fuels, industries, vehicles, mining and waste burning. It causes respiratory and nervous system diseases, smog over cities and acid rain.

Key points

• Noise pollution is unwanted, unbearable sound from traffic, industries, construction, loudspeakers and fireworks; sound level is measured in decibels (dB). It causes stress, hearing loss and sleep disturbance.
• Land pollution results from improper disposal of waste, overuse of chemicals in farming, mining and industrial waste dumping.
• Urban waste disposal: cities generate large quantities of solid waste (household, commercial, industrial). Uncollected waste blocks drains, breeds flies and rats, spreads disease and pollutes water and air when burnt.
• Waste can be converted into resources through segregation, composting, recycling and energy generation.
• Rivers have a natural self-cleansing capacity, but heavy pollution loads exceed it.

Exam tips

For each type of pollution, learn two sources and two effects. Remember the unit of noise: decibel.

Common mistakes

Acid rain is a result of air pollution (sulphur and nitrogen oxides), even though it affects soil and water.