Emissions Inspector Certification Test
Questions and Correct Answers.
air pollution - Answer the contamination of the atmosphere by the introduction of pollutants
from human and natural sources
United States Environmental Protection Agency (EPA) - Answer Estimated that 20% of all US
pollution comes from cars and trucks
Major pollutants from vehicles - Answer Hydrocarbons (HCs), Carbon Monoxide (CO), Nitrogen
Oxides (NOx). Other pollutants include Sulfur Dioxide (SO2) and Particulate Matter.
Hydrocarbons - Answer Principal constituents of gasoline, diesel, and natural gas. Excessive
amounts of this pollutant is mainly from incomplete combustion and rich fuel mixtures. Tends to
stay consistent with the stoichiometric ratio.
Nitrogen Oxides - Answer Forms with HC to create smog; mainly formed in vehicle engines
during combustion of fuel at high temperatures. Primary cause of acid rain
Oxygen - Answer Too much or too little is bad and can cause improper combustion. Too little
can be from rich air-fuel mixture, and dirty air filters. Too much can be caused by lean air-fuel
mixture or engine misfires.
Ozone(Smog) - Answer Not emitted directly into the air, but created at ground level by
chemical reactions from NOx and HC. Also known as smog.
Particulates - Answer This matter is released into the air by combustion and can damage the
lungs and cause health problems
Five Gas Theory - Answer Shows how the ratio of each gas to the others changes in response
to different temperatures and fuel mixtures
Lean Mixture - Answer Low ratio of fuel to air
Questions and Correct Answers.
air pollution - Answer the contamination of the atmosphere by the introduction of pollutants
from human and natural sources
United States Environmental Protection Agency (EPA) - Answer Estimated that 20% of all US
pollution comes from cars and trucks
Major pollutants from vehicles - Answer Hydrocarbons (HCs), Carbon Monoxide (CO), Nitrogen
Oxides (NOx). Other pollutants include Sulfur Dioxide (SO2) and Particulate Matter.
Hydrocarbons - Answer Principal constituents of gasoline, diesel, and natural gas. Excessive
amounts of this pollutant is mainly from incomplete combustion and rich fuel mixtures. Tends to
stay consistent with the stoichiometric ratio.
Nitrogen Oxides - Answer Forms with HC to create smog; mainly formed in vehicle engines
during combustion of fuel at high temperatures. Primary cause of acid rain
Oxygen - Answer Too much or too little is bad and can cause improper combustion. Too little
can be from rich air-fuel mixture, and dirty air filters. Too much can be caused by lean air-fuel
mixture or engine misfires.
Ozone(Smog) - Answer Not emitted directly into the air, but created at ground level by
chemical reactions from NOx and HC. Also known as smog.
Particulates - Answer This matter is released into the air by combustion and can damage the
lungs and cause health problems
Five Gas Theory - Answer Shows how the ratio of each gas to the others changes in response
to different temperatures and fuel mixtures
Lean Mixture - Answer Low ratio of fuel to air
