The ____________ system reduces nitrogen oxide emissions by diluting the air-fuel mixture with the exhaust gases.

The __________ is basically a silencer to reduce noise pollution.

A/An  ______________ connects the catalytic converter to the muffler.

 What forms from hydrocarbons, nitrogen oxides, and sunlight?

What three areas is vehicle pollution generally classified? 

Which of the following is a colorless, odorless, and poisonous gas?    

Which of the following is NOT a source of automotive emissions?    

 What smog score is associated with a Zero Emission Vehicle?    

What are fine particles, smoke, and soot from diesel vehicles?    

What emission is not immediately harmful, but is believed by many scientists to contribute to climate change?    

 When diesel fuel sulfur content changed from 500 parts-per-million (ppm) to 15 ppm, it was a _________ reduction.    

 Diesel particulate filters remove _____________.    

What type of system uses diesel exhaust fluid and a catalyst to break nitrogen oxides into nitrogen and water?    

An EGR _______________ is used to reduce combustion chamber temperatures.    

1. control module

2. particulate filter

3. catalyst

4. cooler