Diesel vehicles suspected of using prohibited defeat devices in the EU and UK with detrimental health impacts

Diesel vehicles made prior to the introduction of Euro 6d RDE standards in 2016 produce 10 times more toxic air pollution – specifically nitrogen oxides (NOx) -  than petrol vehicles. Even the latest Euro 6 (post-2016) diesel cars emit five times the NOx of comparable petrol cars, contributing to up to 36,000 premature deaths a year in the UK. In 2015, a combination of investigations revealed that Volkswagen was using prohibited defeat devices for real world driving conditions - a scandal known as Dieselgate. Defeat devices use engine calibration technology to disable or reduce the effectiveness of emission control systems under normal driving conditions i.e. in normal on road conditions emissions are higher than they should be. Defeat devices are varied and can operate in response to a range of vehicle signals, such as temperature, vehicle speed, and engine speed, including some that detect and temporarily reduce emissions when vehicles are undergoing certification testing. Because of their impact on emissions, defeat devices are illegal in both the EU and UK except for a few narrowly defined exceptions.

Since Dieselgate, a wealth of evidence has emerged suggesting the use of prohibited defeat devices across the diesel industry. It is estimated that there are still millions of diesel vehicles from almost all major car manufacturers suspected to be using these devices, resulting in excess emissions. Despite this, for the most part authorities in the UK and EU have been slow to act, leaving these vehicles on the roads, and most manufacturers have yet to face meaningful accountability.

Picture from Jonathan Formento

The Centre for Research on Energy and Clean Air (CREA), partnered with ClientEarth, has produced a health impact assessment that analyses excess NOx emissions from diesel vehicles in the EU and UK between 2009 and 2040 and their health and economic impacts. Excess emissions are emissions that are suspiciously high (more than twice the legal limit) and likely associated with the use of prohibited defeat devices.

Key findings from the report suggest that across the EU and the UK, excess emissions are projected to cause severe public health and economic consequences over this period, including:

• 205,000 (123,000–356,000) premature deaths

• 152,000 (33,000–346,000) new cases of asthma in children 

• 42,000 (15,000–80,000) years lived with chronic obstructive pulmonary disease (COPD) 

• 24,000,000 (20,000,000–27,000,000) work absences (sick leave days)

• Associated economic burden from these health impacts of EUR 1.20 (0.72–2.07) trillion (in 2024 EUR).

Of these impacts, 124,000 (75,000–216,000) premature deaths and EUR 760 (460–1,320) billion in economic impacts have been caused between the period 2009–2024. If no additional measures are taken, 81,000 (48,000–140,000) premature deaths and EUR 430 (260–750) billion in economic impacts are projected between 2025–2040.

As such, the report concludes by recommending immediate intervention by governments and auto manufacturers to reduce future harm and achieve significant health and economic benefits. In addition to these recommendations, the Sustainable Nitrogen Alliance suggests that local authorities should be supported in being able to target all sources of air pollution, even those that don’t originate in their area of jurisdiction. For example, ammonia emissions travel great distances, with agricultural sources proven to contribute more to particulate matter air pollution in Birmingham and London than from these cities’ sources or national transport sources. A holistic strategy to reducing nitrogen pollution across government agencies and departments, with training and resources delegated to local authorities, will enable action to take place across sectors and regions.

Image from Denis Kashentsov