The line graph provides data about the production of nitrogen oxide emissions by four types of vehicles.
Overall, the amount of nitrogen oxide produced by buses and lorries shows a noticeable change as the speed of car increases, while the reverse was true for petrol and diesel cars, emitting the same amount of nitrogen oxide as the speed of car goes up. It is also worth noting that buses are dominant at producing nitrogen oxide.
Examining data closely, it can be seen that buses are active at emitting nitrogen oxide. Starting at 10 kph, buses produce around 40 g/km, yet, then this amount decreases to about 25 g/km when buses reach 60 kph. When the speed of buses increases to 130 kph, their production rate shows skyrocketing rise to approximately 42g/km. The nitrogen oxide production of lorries shows fluctuation at 90kph, which this speed marks its lowest production rate about 20g/km, starting at 10kph producing 33g/km, and ending at about 25 g/km at the speed of 130kph.
By contrast, the amount of nitrogen oxide emitted by petrol and diesel car remains the same, although the speed of car increases, about 10g/km at all speed for petrol car and about 5 g/km for all speed of diesel car.