Study: target farm ammonia before truck emissions

Diesel transport may have been shouldering an unfair proportion of the blame for high levels of urban particulate pollution, when a prominent cause is ammonia fumes blown into towns from nearby farmland.

Research published in the journal Science late last year suggests that 60 per cent of atmospheric PM2.5 particles originate from ammonia given off by agricultural fertiliser application and livestock manure.

The study highlighted that pollution controls introduced since the 1980s have drastically cut PM pollution from vehicles, but ammonia emissions have barely fallen.

PM2.5 can form in the atmosphere when oxides of nitrogen combine with ammonia. This PM2.5 is in addition to the now very small amount of particulate emitted by Euro VI trucks and buses. The study argues that it would be far more cost-effective to reduce ammonia pollution – which can be done by capping slurry tanks and injecting manure and fertiliser directly into the soil rather than spreading it on the surface – than attempt further reductions of emissions of NOx and PM from diesel vehicles.