5 Pollution and Environmental Health
Learn how air, water, and soil pollution arise, affect health and ecosystems, move through the environment, and can be prevented or addressed.
How Pollution Moves and Creates Risk
Pollution occurs when substances or forms of energy enter the environment at levels that harm people, other organisms, or ecosystems. Pollutants can move between air, water, and soil: may settle onto land or water, while contaminated soil can release pollutants into groundwater, waterways, or dust.
The risks depend on the , its amount, how long exposure lasts, and how people or wildlife encounter it. Pollution can affect both human health and ecosystems.
Outdoor can come from vehicles, power plants, industry, burning waste, and some agricultural activities. Smoke from cooking or heating with polluting fuels can affect indoor air.
Major air pollutants include fine particles, carbon monoxide, nitrogen dioxide, sulfur dioxide, and . forms when other pollutants react in sunlight. It is different from the protective ozone layer high in the atmosphere.
Breathing polluted air can irritate or damage the lungs. is linked to respiratory and cardiovascular disease, stroke, and lung cancer. It can also harm plants and ecosystems, and some pollutants contribute to climate change or acid deposition. Exposure is not evenly distributed: people living near busy roads or industrial sources may face higher risks.
The most effective prevention measures reduce pollution at its source. These include cleaner energy and industrial processes, efficient public transport, walking and cycling infrastructure, and cleaner household cooking and heating. Properly maintained vehicles and avoiding open burning can also reduce emissions. Because major sources are often beyond individual control, effective prevention requires community planning and public policies as well as personal choices.
occurs when harmful substances or disease-causing organisms enter rivers, lakes, oceans, or groundwater. Some pollution comes from identifiable outlets, such as a wastewater pipe; other pollution is diffuse. Rain or snowmelt can wash fertilizers, pesticides, animal waste, oil, road chemicals, and sediment from farms, streets, and construction sites into waterways. Untreated or inadequately treated sewage and industrial discharges are additional sources.
Microbes in contaminated drinking water can cause illnesses such as diarrhea, cholera, and typhoid. Chemical contaminants, including some metals and agricultural chemicals, can also threaten health. Excess nitrogen and phosphorus may trigger algal growth. As the algae die and decompose, oxygen levels can fall, stressing or killing fish and other aquatic organisms. Pollution can damage drinking-water supplies, recreation, fisheries, and wildlife.
Prevention includes treating sewage and industrial wastewater before discharge, preventing spills, disposing of chemicals properly, and reducing excess fertilizer and pesticide use. Vegetated streamside buffers, wetlands, rain gardens, and permeable surfaces can slow and trap some pollutants before they reach waterways. Protecting drinking-water sources and monitoring water quality help identify risks early.
Example: After heavy rain, from a fertilized field can carry nutrients into a lake. If the added nutrients fuel a large , decomposition may use up , leaving less available for fish. Using fertilizer carefully and maintaining a vegetated buffer can help reduce this pathway.
Soil can be contaminated by pesticides and fertilizers, leaking fuel tanks, mining, industrial waste, landfills, or pollutants deposited from the air. Some harmful elements, such as arsenic, also occur naturally in certain places.
People may be exposed by swallowing or inhaling contaminated soil or dust, through skin contact, or by eating food grown in contaminated soil. Some contaminants can harm human health; others can injure plants and wildlife, reduce soil quality, or move into groundwater and surface water. Contamination can persist, so a site may remain hazardous long after the original activity has stopped.
Prevention includes preventing leaks and spills, storing and disposing of hazardous materials safely, and using agricultural chemicals according to appropriate guidance. At contaminated sites, authorities may restrict access, contain pollutants, remove contaminated soil, or treat it. Treatment methods may break down pollutants or extract them from soil. The suitable response depends on the contaminants and the likelihood of exposure.
Connecting Sources, Effects, and Solutions
Air, water, and can harm human health and ecosystems, and pollutants can travel between these parts of the environment. Common sources include fuel burning, wastewater, agricultural , industrial activity, and improper waste disposal.
Preventing pollution at its source—supported by treatment, careful land and water management, monitoring, and cleanup—helps protect communities and ecosystems.