Environmental Pollution

• Pollution is the introduction of contaminants into the natural environment that result in adverse changes and disruption of ecological balance.

• These contaminants can be chemical substances or forms of energy such as noise, heat, or light.

• Environmental pollution is one of the most serious global challenges faced by humans and other life forms on Earth today.

• It refers to the contamination of the physical and biological components of the Earth/atmosphere system, leading to the disruption of normal environmental processes.

• Pollution involves the introduction of substances that adversely affect the utility of natural resources like air, water, soil, and biodiversity.

• Pollution can be in solid, liquid, or gaseous form and is caused by industrial activities, vehicular emissions, agricultural chemicals, household waste, and urbanisation.

• It leads to significant damage to human health, plants, and animals, contributing to diseases, ecosystem loss, and climate change.

• Air pollution causes respiratory issues like asthma, lung cancer, and bronchitis, especially in urban and industrial areas.

• Water pollution results in the contamination of rivers, lakes, and groundwater, affecting drinking water sources and aquatic life.

• Soil pollution affects agricultural productivity and contaminates food chains with toxic substances.

• Noise and light pollution disturb both human health and wildlife behavior, causing stress, sleep disorders, and loss of natural rhythms.

• Environmental pollution is essentially the excessive discharge of harmful substances into the environment that lowers the quality of air, water, and soil.

• According to the World Health Organization (WHO), around 7 million people die each year due to exposure to polluted air.

• Preventing pollution requires regulation of emissions, waste management, promotion of clean energy, and public awareness for sustainable development.

Types of Pollution

• Pollution is generally classified into various types based on the medium affected and source of contaminants

• Air Pollution is caused by the release of harmful gases and particles into the atmosphere from vehicles, industries, burning of fossil fuels, and deforestation

• Water Pollution results from the discharge of sewage, industrial waste, and agricultural runoff into rivers, lakes, and oceans, making water unsafe for drinking and aquatic life

• Soil Pollution occurs due to the excessive use of chemical fertilizers, pesticides, and industrial waste, leading to decreased fertility and contamination of crops

• Solid Waste Pollution is caused by improper disposal of household, industrial, and municipal waste, including plastics, metals, and non-biodegradable materials

• e-Waste Pollution refers to pollution caused by discarded electronic devices such as computers, phones, and appliances, which release toxic metals like lead and mercury

• Noise Pollution is caused by loud sounds from traffic, industrial machinery, airports, and construction activities, leading to hearing problems, stress, and sleep disturbances

• Radioactive Pollution results from leakage or improper disposal of radioactive materials, such as from nuclear power plants or medical waste, causing genetic disorders and cancer risks

• Marine Pollution involves the contamination of seas and oceans by oil spills, plastic waste, chemical runoffs, and shipping waste, severely affecting marine ecosystems and fisheries

• Addressing each type of pollution requires specific mitigation strategies, policy regulations, and public cooperation to protect human health and the environment

Air Pollution

• Air pollution occurs due to the presence of undesirable solid or gaseous particles, particulate matter in the air, in quantities that are harmful for human health and the environment. Unlike pollutants from human activity, naturally occurring pollutants tend to remain in the atmosphere for a short time and do not lead to permanent atmosphere change.
• Sources and effects of major air pollutants are as follows:

Primary Air Pollutants

• Primary pollutants are air pollutants emitted directly from a source.

• Carbon Dioxide (CO₂) is produced when any substance containing carbon is burned; also produced during breathing and fermentation.

• Plants absorb CO₂ through photosynthesis and release some back through respiration; oceans absorb slightly more CO₂ than they release.

• Carbon Monoxide (CO) results from incomplete combustion of carbon-based fuels like petrol, diesel, and wood; it is colorless and odorless.

• About 50% of atmospheric CO comes from automobiles; it reduces oxygen transport in blood, causing confusion, sleepiness, and slowed reflexes.

• Chlorofluorocarbons (CFCs) contain carbon, chlorine, and fluorine; used in air conditioners, refrigerators, fire extinguishers, and cosmetics.

• CFCs rise to the stratosphere, where they react with other gases to deplete the ozone layer, increasing harmful UV radiation reaching Earth.

• Sulphur Dioxide (SO₂) is mainly emitted by burning sulfur-containing coal, smelters, and oil refineries.

• High SO₂ concentration causes severe respiratory problems and damages plants.

• Nitrogen Dioxide (NO₂) forms from nitrogen and oxygen during high-temperature fossil fuel combustion, mainly in automobile engines.

• NO₂ is a reddish-brown toxic gas and participates in forming secondary pollutants like ozone.

• It causes heart and kidney problems, and after mixing with water forms nitric acid (HNO₃), contributing to acid rain.

• Methane (CH₄) is released by soil microbes in flooded rice fields and swamps; it is a potent greenhouse gas contributing to global warming.

• Landfills also generate methane, which is highly flammable and can form explosive mixtures with air.

• Lead (Pb) pollution mainly comes from leaded petrol, lead paint, vehicle emissions, smelters, batteries, hair dyes, and incinerators.

• Lead exposure can cause nervous system damage, digestive problems, and even cancer.

• Particulate Matter (PM) includes solids like smoke, dust, and vapor suspended in air, causing haze and reduced visibility.

• Fine PM particles can penetrate deep into lungs, causing respiratory issues and lung damage.

• Many primary pollutants like CO, SO₂, NO₂, and PM contribute to smog formation and poor air quality.

• Vehicle emissions are a major source of several primary pollutants including CO, NO₂, PM, and lead.

• Controlling primary pollutants is essential to reduce health risks, environmental damage, and combat climate change.