Pollution is defined as the introduction of harmful substances, known as “pollutants”, into the environment. While some substances are inherently harmful, the key factor is the rate of introduction. Pollution occurs when any substance or form of energy is introduced into the environment faster than it can be processed into a harmless form (whether dispersed, diluted, decomposed, recycled, or stored; Encyclopaedia Britannica).

Pollution may be a result of natural phenomena, like volcanic ash from eruptions, but is more typically caused by human activity. Anthropogenic sources of pollution pose unique threats to the environment, making it increasingly difficult for nature to maintain its equilibrium. While humans have always introduced materials to the environment, meaning there has always been some small amount of pollution as far back as 500 AD, it has not posed the significant cross-continental issues that it does today. Pollution is now an international crisis that debilitates socio-economic growth, threatens wildlife populations and overall biodiversity, and has been linked to multiple human health conditions, crippling the quality of life for many. Due to industrialization and rapid population growth (with over 8.2 billion persons globally), more resources are required than ever before to meet the needs of the human population, including food production, infrastructure, and energy production. Moreover, with the growing desire to be a part of global trends, there is also an overconsumption epidemic, driving producers to keep up with this excessive demand by producing cheap, often plastic-based, trinkets and fast fashion items that are not designed to last. These industrial activities have led to most of the atmospheric and surface pollution present in our environment.

“Pollution and the unsound management of chemicals and waste, together with environmental degradation and biodiversity loss, and climate change are intertwined planetary crises with negative impacts on the health of both humans and animals.”

— United Nations Environment Programme

Types of Pollution

Contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere (World Health Organization 2024 Air Pollution).
Typically, the gases that contribute to this form of pollution include carbon dioxide, methane, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide.
Sources: vehicle exhaust, factories, burning fossils fuels.
Effects: respiratory problems; acid rain; global warming; ozone layer damage.
Contamination of water bodies with harmful substances, which can degrade water quality, making it harmful for humans and wildlife, and disrupting the natural functioning of ecosystems.
Sources: industrial waste, sewage, oil spills, agricultural runoffs including fertilizers and pesticides.
Effects: Death of aquatic life; unsafe drinking water; spread of disease.
The presence of toxic chemicals within the soil, in concentrations high enough to pose risks to both human and ecosystems' health.
Sources: chemical waste, pesticides, landfills and oil spills.
Effects: Reduced soil fertility; food contamination; health problems in humans.
Sources: Traffic, construction, loudspeakers, airplanes, boat engines, underwater military testing
Effects: Hearing loss; stress; disturbed sleep; disorientation and even death of animals that rely on acoustic communication, e.g., birds, bars, whales and dolphins
Source: Factories and power plants discharging water into rivers and lakes, including rum factories, large data centers for AI tools
Effects: reduced oxygen levels; disruption metabolic processes of fish etc.; in extreme cases death of aquatic wildlife
Sources: Excessive artificial lighting from buildings, towers, etc.
Effects: Affects nocturnal wildlife and those active at night, e.g., sea turtles, migrating birds; disrupts human sleep patterns; obscures night sky.
Plastic pollution is particularly dangerous as plastic is a persistent material that takes centuries to degrade. Within a human lifespan, all the plastic we use will break down into smaller and smaller pieces, but never completely degrade. These microplastics are now present everywhere on Earth, including in the food we eat, causing health problems that are only just being investigated.
Everything you should know about microplastics
Sources: improper disposal of plastic, spills from shipping containers
Effects: endangers marine life through entanglement or ingestion