Pollution Pollution: A Rising Environmental Problem

Pollution is the addition of any constituent to air, water or land that lowers the natural quality of the environment and harms living things. The substance that causes it is called a pollutant. Pollutants may be gases such as carbon monoxide and sulphur dioxide, liquids such as sewage and industrial effluents, or solids such as plastic and metal scrap. The four main kinds studied are air, water, soil (land) and noise pollution. Most pollution is caused by human activity: factories, vehicles, farming chemicals and the careless dumping of waste.

Waste is unwanted material from homes, farms, mines and industries. It is sorted into two groups. Biodegradable waste can be broken down by microbes (bacteria and fungi) into simple harmless substances that return to nature; examples are vegetable and fruit peels, paper, leaves, cotton, food scraps and sewage. Non-biodegradable waste cannot be broken down by microbes, so it stays in the environment for years and piles up; examples are plastics, polythene bags, glass, metal cans, DDT and aluminium foil. Non-biodegradable waste is the more dangerous of the two because it accumulates and can enter food chains.

Air pollution comes from burning fuels in vehicles and factories, releasing smoke, carbon monoxide, sulphur dioxide and oxides of nitrogen; it causes breathing diseases, acid rain, the greenhouse effect and ozone-layer depletion. Water pollution comes from sewage, industrial effluents, fertilisers and pesticides washing into rivers; it spreads diseases like cholera and typhoid and kills aquatic life. Soil (land) pollution comes from excessive fertilisers and pesticides, industrial waste and dumped solid waste; it reduces soil fertility and lets harmful chemicals enter crops.

Noise pollution is unwanted, loud sound, measured in decibels (dB). It comes from traffic horns, factories, loudspeakers, aircraft and construction. Above about 80 dB sound becomes harmful, and 120 dB causes pain; long exposure leads to deafness, high blood pressure, sleeplessness and irritation. Pollution of every kind is controlled by treating waste before release, using filters and catalytic converters, switching to cleaner fuels and renewable energy, planting trees, recycling and reducing plastic, and obeying laws that limit emissions and noise. The simple rule for an individual is reduce, reuse and recycle.