EFFECT OF GASES ON ENVIRONMENT

Ethanol-blended petrol has advantages and disadvantages for the environment over normal petrol ? the extent of most of them depends on factors such as the percentage of the blend, the engine type and how the ethanol was produced:
A 10% blend generally reduces the car?s emissions of carbon monoxide, hydrocarbons, some carcinogens such as benzene and toluene and ? in some circumstances ? the greenhouse gas carbon dioxide. However, due to the government subsidy, any reduction of carbon dioxide emissions comes at a very high price compared to other initiatives.
Ethanol increases the petrol?s volatility, and therefore the amount of evaporative emissions of volatile organic compounds, which can contribute to global warming and the formation of ground-level ozone (summer smog). This can be avoided by changing the volatility of the petrol used for blending.
There are higher emissions of carcinogenic aldehydes (such as formaldehyde and acetaldehyde) and ? in most cases ? of oxides of nitrogen.
Overall, there seems to be little benefit for urban air quality or greenhouse gas emissions resulting from the use of ethanol-blended petrol. However, as ethanol is produced from agricultural products or waste, it?s a renewable energy source.