Cutting ammonia emissions may be the best way to reduce air pollution
Emissions of ammonia can lead to tiny particles in the air that damage our health, but many countries have no policies on limiting its release into the atmosphere
4 November 2021
Aiming to reduce ammonia emissions may be a more cost-effective way to mitigate air pollution than focusing on nitrogen oxides alone.
Fine particulates less than 2.5 micrometres in diameter are formed when ammonia reacts with nitrous oxides (NOx) and sulphur dioxide. These particulates, known as PM2.5, can pass from the lungs into the bloodstream and cause illnesses such as asthma, coronary heart disease and chronic obstructive pulmonary disease.
“Nitrogen is an important precursor that can lead to air pollution, so if we want to control air pollution, we have to control nitrogen emissions to the air,” says Baojing Gu at Zhejiang University in China. “But there are too many different types of nitrogen emitted to air.”
Gu and his colleagues developed a new way to calculate the contribution of nitrogen compounds to PM2.5 pollution called the N-share. They estimate that, in total, nitrogen emissions caused roughly 23.3 million years of lost life in 2013, with an economic cost of $420 billion.
The team found that targeting ammonia emissions – the majority of which come from agricultural sources such as livestock production – would be a more cost-effective way to reduce PM2.5 pollution than focusing on NOx emissions, which are produced chiefly by combustion, such as in car engines.
Updating the way we produce meat, for example via changes to animal housing and diet, could help reduce ammonia emissions, since about 80 per cent comes from agriculture, says Gu.
Currently, most places around the world focus on reducing sulphur dioxide and nitrogen oxides to tackle fine particulate air pollution. While ammonia reductions have been suggested as a focus for the European Union, other countries, including China and the US, have no policies on ammonia emissions.
“Globally, around 5 million people die each year due to [ambient] air pollution,” says Gu. “We want to change policymaking to focus on not only NOx, but ammonia for PM2.5 pollution.”
Journal reference: Science, DOI: 10.1126/science.abf8623
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