Pollution refers to the presence of harmful substances in environments like air, water and land. The term carries the implication that they have an anthropogenic source—meaning they originate from human activities such as waste disposal, mining operations, manufacturing, overpopulation, transportation and agriculture. It can be classified as either point source pollution (coming from a single, highly concentrated site) or nonpoint source pollution (from the widespread distribution of contaminants such as microplastics or agricultural runoff).
The most common types of pollutants include fine particles and ozone in air, toxic chemicals in water and soil, heavy metals in the environment, and persistent organic pollutants that accumulate in animal tissues and disrupt natural ecosystems. These pollutants can cause a wide variety of health problems, including asthma, cardiovascular disease, and cancers. They also contribute to climate change, which is an issue of global concern requiring collective action.
In addition to the direct harm caused by pollutants, pollution can impact human development by hindering economic growth and social progress. It has a disproportionate effect on the poor, disadvantaged and vulnerable who are unable to protect themselves from the negative effects of pollution. As a result, it can prevent people from achieving health, well-being and prosperity, as well as from meeting the Sustainable Development Goal of “leaving no one behind.”
The world’s leading cause of environmental death is respiratory diseases from exposure to air pollution, which kills about 7 million people per year, 90 percent of them in low and middle income countries. Air pollution is also a significant cause of heart disease, strokes and other cardiometabolic conditions and lower respiratory infections.