What are the origins and environmental implications of pollutants in car exhaust gases? By Oscar Miles

Unburned Hydrocarbons Origin Product from in complete combustion and evaporation Environmental Effects Cancer Asthma Smog Chemical Equations: CxHy + (x + y/4) O2 xCO2 + (y/2) H2O CxHy + (2x + y/4) O2 xCO + (y/2) H2O Hydrocarbons molecules can escape into the air if evaporate from liquid or are not burned before they are released. The effects this has on the environment are: from prolonged exposure can lead to cancer; asthmatics will suffer; can contribute to photochemical smog which can build up when in high concentration and cause a brown haze which restricts sight.

Carbon Monoxide Origin: From incomplete combustion. Environmental Effects Contributes to photochemical smog, Irritation, and high exposure can lead to death. Chemical Equation: O2 + 2 C → 2 CO Carbon monoxide is produced when during combustion there is a lack of oxygen, which leads to incomplete combustion and soot (carbon and carbon monoxide) is emitted. It reacts with other pollutants in the air and creates ground level ozone, which is damaging to humans and the wildlife. Low level exposure to it irritates mucus membranes. High exposure to it leads to death because it causes asphyxia

Particulates Origin In complete combustion Environmental Effects Health problems including: nausea, difficulty breathing, lung cancer and cardiovascular illnesses. Again, produced from incomplete combustion, mainly from diesel. It is made up of very small carbon particles (A.K.A. soot). Very bad for respiratory health; due to its small size it can enter the small airways of the lungs and clog up the alveoli. Also detrimental to plants because it reduces the amount of light that reaches leaves and consequently reduces photosythesis.

Carbon dioxide Origins: Combustion Environmental Effects Can be damaging to health in high concentrations Large contributor global warming Chemical Equation: 2O2 + 2 C → 2 C2O Burning fossil fuels is one of many sources of carbon dioxide. Other sources are plant and animal respiration and decaying material. It is a large contributor to global warming because it helps to trap heat radiation in. This causes the temperature to rise. It is known as a green house gas because of this.

Nitrogen Oxides (NOx) Origin: combustion of nitrogen in air. Environmental Effects Toxic to humans - Causes acid rain Contributes to photochemical smog Damages ozone layer Chemical equations: N2 + O2 → 2NO 2NO + O2 → 2NO2 Produced from the combustion of nitrogen bearing fuels such as certain coals and oils. Forms nitrogen oxide (NO) and nitrogen dioxide (NO2). Again, it is a contributor to photochemical smog and is damaging to human health. Nitrogen dioxide is acidic and consequently creates acidic rain. This is very damaging to the environment and limestone buildings/structures.

Sulphur Dioxides (SOx) Origin - Forms when sulphur combusts in air Environmental effects: Damaging to humans, plant and animal life Acid rain. Chemical Equations: S + O2 → SO2 2SO2 + O2 → 2SO3 Like nitrogen oxides, it is produced when fuels containing sulphur or sulphur compounds combust in air. Similar to nitrogen oxides, sulphur dioxides are damaging to respiratory systems of living organisms. The gas is very damaging to some sensitive lichens. So much so that the amount of growth by certain lichens can be used as a pollution indicator. It is dissolvable in water so creates acid rain.