Ammonia has attracted wide interest as a source of zero-emission fuel for shipping, but a study from MIT has found that burning ammonia could significantly worsen air quality, leading to devastating impacts on public health.

The huge container ships used to deliver cargo across oceans emit large quantities of air pollutants from their diesel engines that drive climate change and have human health impacts. It has been estimated that maritime shipping accounts for almost 3% of global carbon dioxide (CO2) emissions, and that the industry’s negative impacts on air quality cause about 100,000 premature deaths each year.

The International Maritime Organization has set goals to reduce the carbon intensity of international shipping by 70% by 2050 compared to 2008 emission levels.

One potential solution is switching the global fleet from fossil fuels to sustainable fuels such as ammonia, which can be produced nearly carbon-free.

Traditionally, ammonia is made by stripping hydrogen from natural gas...