USA, Arizona, Phoenix, traffic on congested freeway, elevated view

A study carried out in cities in the European Union and in December last year has revealed that Diesel cars produce 10 times more nitrogen oxides (NOx) than trucks, which is quite contrary to the belief that the heavy vehicles cause more pollution. The study was conducted by the International Council on Clean Transportation.

The NOx gases react to form smog and are responsible for acid rain.

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). The bigger engines of buses and trucks, however burn more diesel per kilometre. Thus diesel 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 rings an alarm bell for India, where the number of diesel cars has grown over the years. The Centre for Science and Environment, which has long said that diesel vehicles are far more dangerous than petrol vehicles, has also taken note.

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.

According to Anumita Roychowdhury, executive director, CSE (Center of Science and Evironment),“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.”

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.