Diesel cars produce 10 times more nitrogen oxides (NOx) than trucks, a study conducted by the International Council on Clean Transportation has revealed. The study was carried out in cities in the European Union and was released in December last year.
The study says the average NOx emissions of heavy-duty vehicles was 210 mg/km, less than half the average emissions from cars (480-560 mg/km) in independent testing and Member State testing.
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Buses and trucks, though, have bigger engines and burn more diesel per kilometre. This means that cars produce around 10 times more toxins than trucks when NOx per kilometre is calculated.
The study states that on-road emissions were below the Euro VI engine type-approval limits.
The study has serious implications for India, where the number of diesel cars has grown over the years.
According to the study, in 2014, the percentage of diesel vehicle sales was 52 per cent of total vehicles sales. While fuel and vehicles in Europe are of a superior Euro VI standard, fuel quality in India is still Bharat Stage III and IV — equivalent to Euro III and IV. Even if some luxury cars have a Euro VI engine, it will pollute more because fuel is still of a poorer quality.
“More diesel vehicles are sold in Europe than in China, India and the whole of America combined — over 8.8 million in 2014 alone. The majority of diesel vehicles sold in Europe, as in the global market, are passenger cars; approximately five diesel passenger cars were sold worldwide for every heavy-duty vehicle,” it says.
On-road testing of vehicles revealed that under normal operation many of these vehicles far exceed the limits imposed by regulation and certified by official-type approval tests, which all vehicle models must pass as a condition of being offered for sale in the European Union.
Euro VI emission standards are far superior to the Euro III and IV standard of fuel that is used in India currently.
The study has started ringing alarm bells in India. The Centre for Science and Environment, which has long said that diesel vehicles are far more dangerous than petrol vehicles, has also taken note.
“The study has huge implications for us. So far, we thought trucks were the big pollutants. If cars are polluting more than trucks, it is a serious public health concern, especially in India where diesel is cheaper than petrol,” said Anumita Roychowdhury, executive director, CSE.
Petrol costs Rs 70.6/litre in Delhi while a litre of diesel costs Rs 57.8. Nitrogen oxide and particulate matter are among the primary pollutants in Delhi.
ICCT officials in India said it is not possible to immediately make a car-versus-truck comparison similar to the EU right now, as there are little or no on-road emission data collected for heavy-duty vehicles in India. On-road emissions, however, are higher than what is tested in the laboratory.