You’ve heard of managing your carbon footprint. But how about your nitrogen footprint? Emissions of reactive nitrogen into the environment have increased more than 10-fold over the past 150 years, contribute to deaths from air pollutionand water pollution, and have countless other impacts including acid rain anddegradation of ecosystems such as the Great Barrier Reef.
Now, for the first time, researchers have calculated the average nitrogen footprint of people from 188 countries, as well as where exactly they cause that pollution, helping pave the way to policy that could help the world reduce its emissions of reactive nitrogen.
Almost 80% of the atmosphere is made of nitrogen in the form of N2. But in that fom it hardly interacts with other chemicals – so it is not useful for humans or plants, and it is not harmful either. And for most of Earth’s history, pretty much the only way N2 could be turned into a reactive form like ammonia or nitrous oxide (also known as laughing gas) was either by bacteria, lightning and legumes.