ABYC Diesel Practice Exam

What dangerous gas is produced in small amounts by diesel exhaust systems?

1. Nitrogen Dioxide

2. Carbon Dioxide

3. Hydrogen Sulfide

4. Carbon Monoxide

The correct answer is: Carbon Monoxide

The correct answer is carbon monoxide. Diesel engines, like other internal combustion engines, produce exhaust gases as a byproduct of fuel combustion. Carbon monoxide is a colorless, odorless gas that can be produced in small quantities during the incomplete combustion of diesel fuel. Because it is difficult to detect without proper monitoring equipment, it poses significant risks, particularly in closed or poorly ventilated spaces where exhaust gases can accumulate. While nitrogen dioxide is also a harmful byproduct, it is more commonly associated with gasoline engines. Carbon dioxide is typically produced in larger quantities and is not considered dangerous in itself, though it contributes to greenhouse gas emissions. Hydrogen sulfide is more associated with certain industrial processes and is not a common byproduct of diesel engines. Therefore, carbon monoxide stands out as the hazardous gas associated with diesel exhaust systems due to its potential for toxicity in confined spaces.