A scientist has revealed that nitrogen pollution from fertilizers and other sources has become a major environmental problem that threatens human health and welfare in multiple ways. Billions of people owe their lives to nitrogen fertilizers - a pillar of the fabled Green Revolution in agriculture that averted global famine in the 20th century- but according to Alan Townsend it can have detrimental affect on health and environment. Townsend said that awareness has grown, but nitrogen pollution remains such a little-recognized environmental problem because it lacks the visibility of other kinds of pollution. People can see an oil slick on the ocean, but hundreds of tons of nitrogen spill invisibly into the soil, water and air every day from farms, smokestacks and automobile tailpipes. But the impact is there -unhealthy air, unsafe drinking water, dead zones in the ocean, degraded ecosystems and implications for climate change. People don&rsquot see the nitrogen spilling out, so it is difficult to connect the problems to their source .The concern focuses on so-called &ldquoreactive&rdquo nitrogen. Air contains about 78 percent nitrogen. But this nitrogen is unreactive or &ldquoinert,&rdquo and plants can&rsquot use the gas as a nutrient. A single atom of reactive nitrogen can contribute to air pollution, climate change, ecosystem degradation and several human health concerns,&rdquo said Townsend, an ecology and evolutionary biology professor at the University of Colorado at Boulder. Damage to the ecosystem - a biological community interacting with its nonliving environment &mdash includes water pollution and reduced biological diversity, including the loss of certain plant species. The result was presented at the 242nd National Meeting and Exposition of the American Chemical Society (ACS recently.