Which one of the following statements about air pollution caused by diesel engines is correct ?

Diesel engine emissions are heavily influenced by combustion temperatures. Carbon monoxide (CO) is primarily a product of incomplete combustion, which occurs when the gas temperature is insufficiently low or there is a lack of available oxygen. Conversely, nitrogen oxides (NOx) are formed through the thermal fixation of atmospheric nitrogen and oxygen, a process that is highly temperature-dependent. Significant NOx formation occurs at high temperatures, typically above 1300°C, where molecular nitrogen dissociates and oxidizes. While diesel engines are generally more efficient due to higher combustion temperatures, this same characteristic leads to higher NOx levels compared to petrol engines. Therefore, diesel engines produce large quantities of CO at lower temperatures due to incomplete combustion and large quantities of NOx at high temperatures due to thermal oxidation.

Sources

1. [1] https://www.sciencedirect.com/science/article/abs/pii/S0048969721048646