Pollution & its Classification

By Akhil Gupta|Updated : April 29th, 2021






































































Environmental degradation has become a “common concern” for humankind over the past few decades. The distinctive nature of the present environmental problems is that they are caused more by anthropogenic than natural phenomena. Universal environmental pollution, including greenhouse gas emissions and acid deposition, as well as water pollution and waste management is deliberated as global public health problems, which should be examined from manifold perspectives such as social, economic, legislative, and environmental engineering systems, as well as lifestyle habits, helping health promotion and reinforcing environmental systems to repel adulteration. It is observed that the problems of environmental pollution are intense in the developing world, where traditional sources of pollution such as industrial emissions, poor sanitation, insufficient waste management, polluted water supplies, and exposure to indoor air pollution from biomass fuels affect humans. Recently, modern pollutants have emerged which are associated with traffic congestion and the use of modern chemicals in the home, in food, for water treatment, and for pest control.

Pollution is broadly classified into:

  •  Air pollution
  • Water pollution
  • Land pollution
  • Marine pollution
  • Thermal Pollution
  • Noise pollution

Pollutants are any substance that causes pollution. They can be

  • Gases (eg- SOx, NOx)
  • Particulate matter (eg- PM10, PM2.5)
  • Radioactive substances (eg- Uranium, Radium)
  • Bio wastes (eg- food waste, agricultural residues)
  • Non-biodegradable substances (ex-plastics)
  • Persistent chemicals (ex- DDT)
  • Heavy metals (ex – Mercury, Lead)


Air Pollution has emerged as a growing global issue among environmentalists and researchers especially in developed countries since the decade of 1960. It affects human and animal lives, natural ecosystems, and the man-made environment.

Air pollution in urban areas has numerous health impacts such as a shorter lifespan for city inhabitants. Air pollution is also responsible for climate change due to the enhanced greenhouse effect, acid rain, and the depletion of the ozone layer that constitute important global environmental problems.

Air pollution is mainly due to gaseous pollutants like NOX and particulate matter like dust. The main sources of pollutants are exhaust from combustion engines, fires, dust from construction activities.

Air Pollutant: An air pollutant is a material in the air that can have adverse effects on humans and the ecosystem. The substance can be solid particles, liquid droplets, or gases.

A pollutant can be of natural origin or man-made.

Pollutants are classified as primary or secondary.

Primary pollutants are usually produced by processes such as ash from a volcanic eruption. Other examples include carbon monoxide gas from motor vehicle exhausts or sulfur dioxide released from factories.

Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. Ground-level ozone is a prominent example of a secondary pollutant.

Some pollutants may be both primary and secondary: they are both emitted directly and formed from other primary pollutants.


Water is a crucial resource for all existence on this earth as well as an essential part of the global ecological system. Water quality and quantity problems are a major concern in all countries. Nevertheless, specific situations of water issues can differ from region to region and from country to country.

Water stocks on earth can be divided into two categories i.e.



The total volume of water on earth is about 1386 million cubic km. Only 2.5 percent of the total volume of water is fresh water and less than 1 percent of all freshwater is directly available for human use.

Water is an important natural resource used for drinking and other developmental purposes in our lives. Safe drinking water is necessary for human health all over the world. Being a universal solvent, water is a major source of infection. According to the world health organization (WHO), 80% of diseases are waterborne. Drinking water in various countries does not meet WHO standards 3.1% of deaths occur due to the unhygienic and poor quality of water.

Water pollution occurs when untreated waste is released into bodies of water.

There are four main categories of water pollution:

  • Pathogens
  • Inorganic compounds
  • Organic material
  • Macroscopic pollutants.


The deposition of solid or liquid waste materials on land or underground in a manner that can contaminate the soil and groundwater, threaten public health, and cause unsightly conditions and nuisances are consider Land Pollution.

Various Causes of Land Pollution:

  • Deforestation and Soil Erosion
  • Agricultural Activities
  • Mining Activities
  • Overcrowded Landfills
  • Industrialization
  • Urbanization
  • Construction Activities
  • Nuclear Waste
  • Sewage Treatment
  • Littering

Disastrous Effects of Land Pollution

  • Soil Pollution
  • Drinking-Water Problem
  • Groundwater Poisoning
  • Change in Climate Patterns
  • Environmental Impact
  • Effect on Human Health
  • Distraction for Tourists
  • Wildfires
  • Habitat Shifting



Marine pollution occurs when harmful effects result from the entry into the ocean of chemicals, particles, industrial, agricultural and residential waste. Eighty percent of marine pollution comes from land. Air pollution is also a contributing factor by carrying off pesticides or dirt into the ocean. Land and air pollution have proven to be harmful to marine life and its habitats.

Generally, there are three main types of inputs of pollution into the ocean:

Direct discharge of waste into the oceans

Runoff into the waters due to rain, and

Pollutants released from the atmosphere

Marine pollution comprises many types of pollution that disrupt the marine ecosystem, including plastic, light, noise, and chemical pollution.

Plastic Pollution:

Plastics are one of the biggest man-made pollutants in the marine environment, with an estimated eight million tonnes of plastic waste finding its way into our oceans each year. The build-up of plastic litter - bottles and cups, plastics found in cigarette filters, straws, and other ‘macroplastics’ (those which are larger than 5mm) – in these urban coastal areas drift out to sea in heavy rain, eventually polluting coastal waters. A plastic bottle can last up to 450 years in the marine environment.

Light Pollution:

Since the invention of the lightbulb, light has spread across the globe, reaching almost every ecosystem. Light pollution penetrates under the water, creating an enormously different world for fish living in shallow reefs near urban environments. Light disrupts the normal cues associated with circadian rhythms, to which species have evolved timing of migration, reproducing, and feeding.

Noise Pollution:

Marine life can be susceptible to noise or sound pollution from sources such as passing ships, oil exploration, seismic surveys, and naval low-frequency active sonar. Sound travels more rapidly and over larger distances in the sea than in the atmosphere. Marine animals, such as cetaceans, often have weak eyesight, and live in a world largely defined by acoustic information. Unnatural noises interrupt communication, disrupting migration, communication, hunting, and reproduction patterns for many marine animals.

Chemical Pollution:

Chemical contamination, or nutrient pollution, has major concerns for health, environmental, and economic reasons. This type of pollution occurs when human activities, notably the use of pesticides, herbicides, fertilizers on farms, detergents, oil, industrial chemicals, and sewage lead to the runoff of chemicals into waterways that ultimately flow into the ocean. The greatest volume of waste discharged to water is sewage, which is primarily organic in nature and is degraded by bacterial activity.

Thermal pollution

Thermal pollution, often called "thermal enrichment," is the degradation of water quality by any process that changes ambient water temperature. Thermal pollution comes from hot water or cold water being dumped into a body of water. Fish and other organisms adapted to a particular temperature range can be killed by an abrupt change in water temperature (either a rapid increase or decrease) known as "thermal shock."


Noise pollution is generally defined as regular exposure to elevated sound levels that may lead to adverse effects in humans or other living organisms. Noise pollution is an invisible danger. It cannot be seen, but it is present nonetheless, both on land and under the sea. Noise pollution is considered to be any unwanted or disturbing sound that affects the health and well-being of humans and other organisms.

Few Environmental laws for controlling pollution

  • 1986 - The Environment (Protection) Act
  • 1991 - The Public Liability Insurance Act and Rules and Amendment
  • 1995 - The National Environmental Tribunal Act
  • 1997 - The National Environment Appellate Authority Act
  • 1999 - The Environment (Siting for Industrial Projects) Rules
  • 2000 - The Ozone-Depleting Substance (Regulation & Control) Rules
  • 2002 - The Biological Diversity Act

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