Carbon Dioxide (CO2) Complete combustion of carbon in fuel
Global warming
Carbon Monoxide (CO) Incomplete combustion of carbon in fuel
Smog
Sulfur Dioxide (SO2) Combustion of sulfur in fuel
Smog, acid rain
Nitrogen Oxides (NOx) Byproduct of most com- bustion processes
Acid rain
Nitrogen Dioxide (NO2) Byproduct of some com- bustion processes
Global warming
Water vapor (H2O) Combustion of hydro- gen in fuel
Localized fog
Particulate Matter (PM) Unburned or partially unburned carbon and hydrocarbons, also dirt and ash in fuel
Smog