Passenger Vehicle Emissions
In cities around the globe, personal cars and trucks are the single greatest cause of air pollution. If the combustion of the gas and diesel fuels we burn in our vehicles were complete, the end products would be water (H20) and carbon dioxide (CO2), a gas that is harmless to health, although it contributes to global warming.
However, internal combustion engines are less than perfect. Typically, after fuel and air is combined and combusted, the following molecules exit into the atmosphere:
Hydrocarbons, Nitrogen Oxides, Carbon Dioxide, Carbon Monoxide, Water
Hydrocarbon emissions consist of unburned hydrocarbons or partially burned hydrocarbon fragments. In the presence of nitrogen oxides and sunlight, hydrocarbons form ground-level ozone, a major component of smog. The health effects of ozone include irritation of the eyes, nose and throat and damage to the lungs. Additionally, some exhaust hydrocarbons are toxic, and a number have the potential to cause cancer.
During combustion, nitrogen and oxygen atoms combine to form nitrogen oxides. Catalytic converters in car exhaust systems break down heavier nitrogen gases, forming nitrogen dioxide (NO2) – 300 times more potent than carbon dioxide as a greenhouse gas. NO2 makes up about 7.2 percent of the gases that cause global warming.
Carbon monoxide (CO), a colorless, odorless, poisonous gas, results from fuel burning incompletely due to insufficient oxygen. An estimated two-thirds of carbon monoxide emissions come from transportation sources, with cars generating the largest portion. In urban areas, passenger vehicles can contribution in excess of 90% of all carbon monoxide pollution. The symptoms of carbon monoxide poisoning are: headache, nausea, shortness of breath, dizziness and confusion.
While carbon dioxide is not a direct health concern, the U.S. Environmental Protection Agency (EPA) views it as a pollution concern. Carbon dioxide in the atmosphere acts to trap the earth’s heat, which contributes to the greenhouse effect, or global warming.