Environmental Pollution
Overview
Pollution is the addition of harmful substances or energy to the environment faster than nature can absorb them. This module covers the main types (air, water, soil, marine, noise, thermal and nuclear), how solid waste is managed, and how societies prepare for natural disasters. For each type you will meet the causes, effects, control measures and real cases.
Learning objectives
By the end of this module, you’ll be able to:
- 1Define pollution and explain the causes, effects and control of each major type
- 2Describe how solid waste is classified and managed, including recent Indian rules
- 3Explain the individual’s role in preventing pollution
- 4Describe the main natural disasters and disaster management steps
5.1 Air, Water, Soil and Marine Pollution
Four topics — click to expand each one.
Air pollution
Causes
- Burning fossil fuels in vehicles, power plants and industry
- Burning of biomass, crop residue, waste and household fuels
- Construction dust, mining, and industrial emissions
Main pollutants
Particulate matter (PM10 and the finer, more dangerous PM2.5, particles of 2.5 micrometres or less), sulphur dioxide, nitrogen oxides, carbon monoxide, ozone at ground level, and volatile organic compounds.
Effects
Asthma, bronchitis, heart disease and early death; smog; acid rain; damage to crops and buildings.
Control
- Cleaner fuels and tighter vehicle norms (India moved to Bharat Stage VI in 2020), public transport and electric vehicles
- Scrubbers and electrostatic precipitators in chimneys; catalytic converters in vehicles
- Planting trees, dust control, and no open burning
Cases
Bhopal (1984): a leak of methyl isocyanate gas from a pesticide plant killed thousands and injured hundreds of thousands, India’s worst industrial disaster. London (1952): a deadly smog event that led to clean air laws. Delhi: severe winter smog from vehicles, dust, and crop-residue burning.
Water pollution
Causes
- Untreated domestic sewage and industrial effluents
- Agricultural run-off carrying fertiliser and pesticide
- Oil spills, solid waste dumped in rivers and lakes
- Natural contaminants such as arsenic and fluoride in groundwater, made worse by over-pumping
Effects
- Water-borne diseases (cholera, typhoid, diarrhoea) and chemical poisoning
- Eutrophication: excess nitrates and phosphates feed algae blooms that use up oxygen and kill fish
- High BOD (biochemical oxygen demand) signals heavy organic pollution and low dissolved oxygen
Control
Sewage and effluent treatment plants, preventing industrial discharge, buffer zones along rivers, reduced fertiliser use, and public awareness.
Cases
Minamata, Japan (1956): mercury-contaminated fish poisoned residents. The Ganga and Yamuna: huge cleanup programmes such as Namami Gange (launched 2014–15) target sewage and industrial effluents. Chennai’s Cooum and Adyar rivers show how urban sewage degrades rivers.
Soil pollution
Soil is polluted by chemical pesticides and fertilisers, industrial and mining waste, untreated sewage and plastics, and by salinisation. Contaminants reduce fertility, enter crops and groundwater, and harm soil organisms. Control includes organic and integrated pest management, safe disposal of hazardous waste, cleaning up contaminated sites (bioremediation) and reducing plastics. Cases: the Kasaragod endosulfan tragedy in Kerala; Love Canal (USA), where a neighbourhood was built over buried chemical waste.
Marine pollution
Oceans receive oil, sewage, industrial discharges, plastic and farm run-off carried by rivers. Effects include dead zones, damaged coral reefs and mangroves, and animals entangled in or eating plastic.
- Oil spills: the Exxon Valdez disaster (Alaska, 1989) and the 2017 Ennore spill off Chennai after two ships collided, which coated beaches with oil
- Plastics: millions of tonnes enter the oceans every year; abandoned “ghost” fishing nets trap marine life
Control: international rules on ships (MARPOL), sewage treatment, coastal zone regulation, and bans on dumping.
5.2 Noise, Thermal Pollution and Nuclear Hazards
Three topics — click to expand each one.
Noise pollution
Noise is unwanted sound, measured in decibels (dB). Sources: traffic, aircraft, industry, construction, loudspeakers and fireworks. Prolonged exposure above about 85 dB can damage hearing; noise also causes stress, poor sleep and reduced concentration.
| Area | Day limit (6am to 10pm) | Night limit |
|---|---|---|
| Industrial | 75 dB | 70 dB |
| Commercial | 65 dB | 55 dB |
| Residential | 55 dB | 45 dB |
| Silence zone (hospitals, schools, courts) | 50 dB | 40 dB |
(Noise Pollution (Regulation and Control) Rules, 2000.) Control: silencers, sound barriers, trees, traffic planning, enforcing limits on horns and loudspeakers.
Thermal pollution
Power plants and factories discharge heated cooling water into rivers, lakes and the sea. Warmer water holds less dissolved oxygen, speeds metabolism and can kill sensitive fish and corals or change breeding. Control: cooling towers and ponds, recycling hot water and using waste heat.
Nuclear hazards
Radiation can damage cells, causing burns, cancers and genetic damage. Sources include nuclear power, weapons testing, medical and industrial uses, and radioactive waste, which stays dangerous for very long periods.
- Three Mile Island (USA, 1979): partial meltdown with limited release
- Chernobyl (Ukraine, 1986): explosion spread radioactive fallout across Europe and left a long-term exclusion zone
- Fukushima (Japan, 2011): a tsunami disabled the plant’s cooling, causing meltdowns
Nuclear power emits very little carbon, which is why some countries expand it, but safety, accident risk and waste disposal remain debated. India’s Kudankulam plant in Tamil Nadu has been a focus of such debate.
5.3 Solid Waste, Individual Role and Disasters
Four topics — click to expand each one.
Solid waste management
Solid waste is discarded solid material from homes, industry and institutions. Types include municipal (household) waste, industrial waste, plastic waste, e-waste, bio-medical waste, hazardous waste and construction debris. Urban India generates well over a lakh tonnes of municipal waste every day.
The waste hierarchy
Reduce → Reuse → Recycle → Recover (energy or compost) → Dispose safely. Disposal in landfills should be the last option.
| Method | Notes |
|---|---|
| Composting and biomethanation | Turns wet organic waste into manure or biogas |
| Recycling | Needs good segregation at source |
| Incineration / waste-to-energy | Reduces volume, but emissions must be controlled |
| Sanitary landfill | Lined and managed, not an open dump |
Role of an individual in preventing pollution
- Segregate waste at home; compost kitchen waste
- Refuse single-use plastics; carry a bag and bottle
- Use public transport, cycle or walk; maintain vehicles
- Save water and electricity; never burn waste
- Buy durable and repairable products; dispose of e-waste and batteries properly
- Report violations and take part in clean-up drives
Pollution case studies
- Indore: repeatedly ranked India’s cleanest city after building strict door-to-door segregation and processing
- Pune’s SWaCH cooperative: waste pickers organised as a cooperative providing doorstep collection, showing how informal workers can be partners
- Landfill fires in Delhi and Mumbai: show the dangers of unmanaged dumps
- Great Pacific Garbage Patch: a vast area of ocean debris concentrated by currents
Disaster management: floods, earthquakes, cyclones and landslides
| Disaster | Cause | Mitigation and preparedness |
|---|---|---|
| Floods | Heavy rain, river overflow, blocked drains, loss of wetlands | Floodplain zoning, protecting wetlands, early warning, embankments |
| Earthquakes | Movement of tectonic plates | Earthquake-resistant building codes, drills, retrofitting |
| Cyclones | Intense low-pressure systems over warm seas | Forecasting, evacuation, shelters, coastal green belts and mangroves |
| Landslides | Rain, steep slopes, deforestation, road cutting | Slope stabilisation, no building on unstable slopes, warning systems |
Disaster management covers four phases: mitigation, preparedness, response and recovery. India’s Disaster Management Act, 2005 created the National Disaster Management Authority, state authorities and the National Disaster Response Force.
Cases
- Indian Ocean tsunami (2004): devastated coasts including Tamil Nadu’s Nagapattinam; led to a national tsunami early-warning system
- Bhuj earthquake (2001) and Kerala floods (2018)
- Chennai floods (2015): built-up wetlands and drainage failure worsened the flooding
- Cyclone Fani (2019): about a million people were evacuated in Odisha with good forecasting, greatly limiting deaths
Readings
- Bharucha, Erach. Textbook for Environmental Studies for Undergraduate Courses. University Grants Commission, 2004. (Unit 5: Environmental Pollution.)
- Rao, M.N., and A.K. Datta. Waste Water Treatment. Oxford and IBH, 1987.
- Trivedi, R.K., and P.K. Goel. Introduction to Air Pollution. Techno-Science Publications.
- Central Pollution Control Board: cpcb.nic.in
- National Disaster Management Authority: ndma.gov.in
- Centre for Science and Environment: cseindia.org
Discussion
Which type of pollution affects your daily life most, and what is one change, personal or by authorities, that would reduce it? Post your answer, then respond to a classmate.
Practice quiz
Ungraded — check your understanding before the assignment.
1. PM2.5 refers to:
2. Eutrophication is mainly caused by:
3. The daytime ambient noise limit for residential areas under India’s 2000 noise rules is:
4. How many waste streams must be segregated under the Solid Waste Management Rules, 2026?
5. India’s Disaster Management Act was passed in:
Graded assignment
Pollution case analysis — 400–500 words
Choose one real pollution or disaster case (from this module or a local one). Explain its causes, effects and the control measures used or needed, and say what an individual or community could do. Link your case to at least one law or rule mentioned in this module.
| Criterion | Weight |
|---|---|
| Accurate account of causes and effects | 30% |
| Evaluation of control measures | 30% |
| Link to law or rule; role of individuals | 25% |
| Clarity and structure | 15% |