How Nitrogen Pollution Impacts Public Health and the Environment

Agriculture-based nitrogen pollution impacts public health, drinking water,
air quality, fisheries and the environment.

Everyone knows the story of carbon: the tale of a naturally occurring substance, crucial for life to exist at all, that human interference has turned into a threat to long-term life on earth through climate change. But nearly nobody knows the similarly troubling story of one of the other building blocks of life: nitrogen. You can’t live without nitrogen. If you don’t get enough nitrogen, you die. It is written into every strand of our DNA. It makes up 80 percent of the earth’s atmosphere. But not a single atom of the nitrogen-rich air we breathe in and out can nourish us, or any plant or animal. In this “inert” form, it is inaccessible. All life needs nitrogen in a different “fixed” form that is far less abundant in the natural world. The amount of available fixed nitrogen acted as a limiting factor for life on earth – dictating the amount of plant/crop growth that was possible, and thus the amount of food we could grow. This “cap” on life existed until humans discovered a way to manufacture fixed nitrogen. This has allowed food production to keep up with the steadily increasing human population (at least 2 billion humans would starve today without it). But we’re conducting a global science experiment: all this extra nitrogen is causing dramatic environmental changes, poisoning rivers and lakes, killing huge sections of the ocean and boosting global warming.

Watch “The Nitrogen Problem”

Presented by
Bob Howarth
Professor of Ecology & Environmental Biology, Corenll University


Water Quality

Increased use of nitrogen fertilizers means higher nitrate levels in rivers, lakes and aquifers. In California’s San Joaquin Valley for example, thousands of farm community residents are forced to buy bottled water because their wells exceed safe nitrate levels.

Dead Zones

“Dead zones” are caused when marine waters are essentially over-fertilized by farm and urban runoff laden with excess nitrogen and phosphorus. This pollution spawns algae blooms that consume available oxygen, suffocating aquatic life. In the US, an 8,500 square-mile dead zone in the Gulf of Mexico has hammered the region’s $2.8 billion fisheries.

Air Quality

Ammonia and nitrogen oxides released into the atmosphere from agriculture, industry and urban areas contribute to high levels of particulate matter, ground level ozone, and nitrogen oxides in the air we breathe. Several studies have shown that high levels of ground level ozone and particulate matter cause and worsen cardiac and respiratory disease.

Soil Quality

Reactive nitrogen entering the soil either through fertilisation or atmospheric deposition can make soils more acidic, leading to reduced crop and forest productivity and the release of heavy metals into drinking water supplies.

Climate Change

Pound for pound, nitrous oxide is 300 times more potent than carbon as a greenhouse gas.