It is now common knowledge that carbon dioxide emissions from our vehicles add to the greenhouse effect. But have we ever stopped to ponder what the greenhouse effect is and what the other gaseous emissions do to the environment. The greenhouse effect is when compounds like CO2 are unable to pass through the earth's atmosphere and then begin to trap heat between them and the earth's crust by reflecting light back to earth instead of allowing it to pass through the atmosphere. This in turn has causes the earth's overall temperature to increase. Within the last 100 years it has increased the world's temperature 1degree ever year. This doesn't seem to be a big deal at first but when Islands such as Tuvalu in the south pacific begin to disappear due to the melting glaciers causing the sea level to rise you can begin to see why something needs to be done. .
Though CO2 is the most important greenhouse gas it is not the only emission that comes from a decombustion engine that creates environmental problems. Other gaseous emissions that we don't normally hear about are Nitrogen Oxides (NOx), Sulfur Dioxide (SO2), Hydrocarbons (HC), and Carbon Monoxide. Each one of these gases has there own set of environmental problems that come along with it. Nitrogen Oxide and Nitrogen Dioxide are irritants to the lungs, which can aggravate respiratory problems, in addition to being the main cause of smog alerts in urban areas. It also is a precursor of acid rain and contributes to an over-fertilization of small water bodies which can led to algae blooms ()footnote of the nitrogen cycle. Sulfur Dioxide causes lung irritation and acid rain like Nox but it also interferes with a car part (i.e. catalytic converter) that gives the car the ability to reduce emissions. Some cleaner, reformulated versions of gasoline have very low sulfur levels. These low sulfur gases are mainly concentrated in Europe (Rob) but levels of this gas are being reduced in the U.