The line graph illustrates the amount of nitrogen oxide emitted by four different vehicle types at diverse speeds.
Overall, emissions from all four vehicle types fluctuate significantly with speed. In particular, buses and trucks emit the most nitrogen oxide at their highest speeds, while diesel and gasoline vehicles have fairly stable emissions.
Regarding diesel and gasoline vehicles, emissions are lower than the other two vehicle types. Starting at 10 km/h, diesel vehicles emit slightly higher levels of nitrogen oxide at around 7 g/km, decreasing until reaching a steady level of 5 g/km between 70 km/h and 130 km/h. Meanwhile, emissions from gasoline vehicles remain at around 10 g/km between 10 and 50 km/h, then decreasing as speeds increase. However, compared to diesel vehicles, at vehicle speeds of 120-130 km/h, gasoline emissions increase to around 12 g/km.
In contrast, nitrogen emissions from buses reach their highest values compared to other vehicle types, regardless of speed. Bus emissions start at 40 g/km at 10 km/h, then drop sharply to 25 g/km at 60 km/h. However, buses increase dramatically with speed and peak at almost 45 g/km at 130 km/h. The emissions of lorries started at 33g/km at the lowest speed and dropped sharply, reaching their lowest point of around 17g/km at 90kph. Afterward, they steadily increased again, reaching 25g/km at the highest speed.