What are Car Emissions?

Simply put, car emissions are any fumes that come out of car engines during driving. They are almost always byproducts of gasoline combustion. Most modern cars operate with engines that are powered in whole or part with gasoline, which must be burned to provide power. The fumes are usually made up of three main components: carbon dioxide, nitrogen gas, and water vapor. A number of potentially more toxic gasses are also included in most cases, though, which can make the emissions — sometimes also called “exhaust”— much more harmful. People who are exposed to concentrated inhalation can experience serious brain injury and even death. Many scholars also say that the cumulative effect of car exhaust around the world has contributed to smog and global warming, also called climate change. Governments in most parts of the world require auto manufacturers to mitigate emissions, usually through technology like filters or more efficient engine combustion chambers, to reduce the chance of harm. Drivers are also often responsible for maintaining certain “acceptable” emissions levels in their own cars.

Emissions happen as a normal result of gas combustion. Any time something burns, there’s almost always smoke of some sort. The smoke is made up of some of the key chemical components of whatever it is that is being burned, combined with water, oxygen, and other elements present naturally in the air. Car emissions are no different. When a car ignition switches “on,” a small spark lights gasoline in the tank on fire, which produces heat and energy that the car uses to enable its electrical and mechanical processes. Emissions are the smoke that results as the gas burns off.

A lot of the specific emission composition depends on the type of fuel being burned, as well as the environmental specifics. Carbon dioxide (CO₂), nitrogen gas (N₂), and water vapor (H₂O) are the most common components. Carbon dioxide is a product of combustion; the oxygen in the air is bound to the carbon within the fuel. Nitrogen gas is an odorless, colorless, tasteless, and mostly motionless gas, which makes up approximately 78 percent of the Earth's air. Water vapors are also a product of combustion, and happens as oxygen binds to the hydrogen within the fuel.

These most common components are by no means the only ones. Some of the more dangerous car emissions include carbon monoxide (CO), nitrogen oxides (NO), and hydrocarbons, which are also referred to as volatile organic compounds (VOC). Catalytic converters have been introduced by many manufacturers for the purpose of reducing the more dangerous emissions that car engines produce.

Carbon monoxide is usually considered one of the most dangerous gasses, at least from a human life perspective. It is a colorless, odorless, and poisonous gas. Nitrogen oxides (NO and NO₂, or when combined called NO_x) create problems in the atmosphere such as acid rain and smog; nitrogen oxides also contribute to many of the mucus membrane problems that a lot of people have, including allergies and asthma.

Hydrocarbons, or volatile organic compounds, are chief contributors to smog. The smog created from hydrocarbons is produced primarily from dissolved or evaporated fuel that has not been burnt. Many scholars and researchers have concluded that increased layers of smog have contributed to an inflated and unnatural insulation covering much of the earth, which can trap sunlight and raise ambient temperatures. This has been widely speculated as a cause of the melting polar ice caps and increased incidents of severe weather around the world.

It has also been speculated that emissions can eat away at the ozone layer, which is an atmospheric layer that, among other things, blocks many of the sun’s most harmful rays from reaching the earth. Holes or weak spots in the ozone can lead to a number of different problems.

Modern cars in most places are carefully designed with the intention of managing the quantity of fuel that is burned by maintaining the air-to-fuel ratio as close to a certain point as possible. This point is usually referred to as the “stoichiometric point,” and is believed to be the best ratio of air to fuel possible. The fuel is burned and uses all of the oxygen in the air when it is at this point. Fuel mixture varies significantly from the model ratio when driving, however.

Many different national governments have also set requirements for engine efficiency for the cars, trucks, and other automobiles that are sold within their borders or sometimes even operated on their roads. In addition, drivers in many places must have their cars tested for specific emission outputs on a regular basis. Cars that fail the set guidelines often have to be repaired to lessen exhaust, and drivers also sometimes have to pay a fine.

In addition to regular maintenance and repairs, some of the things that drivers can do to reduce emissions include avoiding unnecessary driving, driving their cars sensibly, and using what’s known as “clean” fuels. Implementing these strategies might also help drivers save money and keep their cars running longer and more efficiently.