Modern Diesel Cars Produce 10 Times More Toxic Air Pollution than Trucks and Buses, New Data Reveals

A new European study has revealed that modern diesel cars actually produce 10 times more toxic air pollution than trucks and buses. The difference in emissions of nitrogen oxides (NOx) between two types of vehicles is because there are much stricter regulations in the EU for heavy duty vehicles than cars. Diesel cars have to meet only lab tests, and therefore produce much more NOx on actual roads.

NOx are released due to burning of fossil fuels or from motor vehicle exhaust. Every year, thousands of people in Europe die because of NOx pollution, with the UK suffering a specifically high toll. Diesel cars, which are very popular in the EU, contribute immensely to these toxic emissions in Europe.

The new study, carried out by the International Council on Clean Transportation (ICCT), shows that buses and trucks tested in Finland and Germany emitted about 210mg NOx per kilometer driven, compared to 500mg/km produced by diesel cars meeting “Euro 6” emission standards. Because engines of buses and trucks are larger and burn more diesel per kilometre, it means diesel cars actually produce about 10 times more NOx per litre of fuel.

According to the ICCT report, there are much stricter regulations for testing of heavy duty vehicles. Mobile testing devices are actually used to measure NOx emissions from trucks and buses on actual roads. On the other hand, tests to measure emission from cars are carried out in the lab for prototype vehicles. The result is that diesel cars under real-world conditions produce more pollution.

“In contrast, for measurement of NOx emissions from trucks and buses, mobile testing devices became mandatory in 2013. As a consequence, randomly selected vehicles can be tested under real-world driving conditions,” said Peter Mock, managing director of ICCT in Europe.

Following the Volkswagen “dieselgate” scandal, ICCT researchers suggest that same stricter testing standards should be applied to cars as well.

In EU, changes to the car testing regime are due to start in September, when portable emissions measurement systems (PEMS) will be attached to cars as they drive on real roads.

However, Mock warned: “Manufacturers will still be allowed to carefully select special prototype cars for emissions testing. Instead, it would be much better to measure the emissions of ordinary mass-production vehicles, obtained from customers who have had been driving them in an ordinary way.”

In US, such a system is already in use, and European commission is due to discuss about use of such system in a meeting on 17 January, although some vehicle makers and EU member states are expected to oppose use of such a system in diesel cars in EU.

It is interesting to note here that in early December, legal action was started against the UK and six other EU states by the European commission for not taking enough steps against car emissions cheating. However, a draft European parliament inquiry in the same month also found that the European commission has failed to handle the issue properly and failed to act quickly enough.