Nitrogen oxides (NOx) from diesel vehicles like cars, buses and trucks could be to blame for around 38,000 premature deaths a year.

A new study suggests one-third of the emissions from the heavy vehicles, and over half of those from the lighter cars in 11 markets around the world exceed certification limits for NOx.

The authors say that diesel vehicles from these regions, including from Australia, emitted approximately 4.6 million tons of the noxious fumes above the limits worldwide leading to 38,000 premature deaths in 2015.

On-road diesel vehicles produce approximately 20 per cent of global anthropogenic emissions of nitrogen oxides.

Despite the tightening of emission limits, current diesel vehicles emit far more nitrogen oxides under real-world operating conditions than during laboratory certification testing.

Researcher Susan Anenberg and colleagues produced a detailed inventory of real-world nitrogen oxides emissions in 2015 from diesel vehicles in 11 markets (Australia, Brazil, Canada, China, the European Union, India, Japan, Mexico, Russia, South Korea and the US) that make up approximately 80 per cent of global new diesel vehicle sales.

The authors estimate that diesel vehicles in these regions emitted approximately 4.6 million tons of nitrogen oxides in excess of certification levels in 2015.

Heavy-duty vehicles were found to be the dominant contributor to excess diesel emissions and the associated impact on public health in all regions, except in the European Union.

The authors suggest that implementing the most stringent current emissions standards for heavy-duty vehicles in regions where they have not yet been adopted (Australia, Brazil, China, Mexico and Russia) could avoid 104,000 premature deaths in 2040, based on their projections.

The study is accessible here.