The line graph illustrates the nitrogen oxide emissions released from diesel, petrol, lorries, and buses at different speeds.
Overall, a diesel car is the most eco-friendly transportation compared to the three others while buses show the highest harmful emissions released. Excepting the remaining unchanged changes of petrol and diesel cars, it is noticeable that the trend of lorries and buses fluctuates according to the changes in speed.
When driving at 10 KPH, buses discharge the largest amount of nitrogen oxide emission into the atmosphere at around 40 g/km, which is higher by almost 7 g/km than that of lorries. Buses decrease gradually the quantity of emissions when reaching 60 KPH from approximately 40 to 25 g/km. From 60 to 130 KPH, the emissions discharged from buses increase constantly to nearly 45 g/km. By contrast, there is a fluctuation in the amount of nitrogen oxide emitted from lorries, including a significant decrease between 60 and 90 KPH and dramatic growth from over 90 KPH.
In terms of Diesel and petrol cars, the figures for the two vehicles seemingly remain unchanged at around 5 and 10g/km respectively according to the speed increased.
