The aircrafts which operate at higher altitudes emit vapour trails which increase the formation of Cirrus clouds. Records show that the aviation development has increased the clouds coverage by 0.2%.These aircraft also produce chemicals, most of which are nitrogen compounds. These chemicals damage the protective layer of ozone. As a result, the dangerous radiations from the sun reaches directly to the earth causing dangerous diseases including cancer.Many aircraft use avgas (Aviation Gasoline) as a fuel. It contains tetra-ethyl lead (TEL) that is a highly toxic chemical. It causes soil pollution at airports. It also pollutes the air and causes various respiratory problems.COUNTERMEASURES:The greatest threat caused to the environment is in the form of the chemical gases that emit out of the aviation aircraft. So, these should be considered specifically. First of all, improvement in the design of aircrafts engine is required. An engine which reduces the emission of toxic gases such as Carbon dioxide, Carbon monoxide, and nitrogen oxides is required. This may greatly reduce the environmental pollution caused due to these gases. Despite manufacturing new engines, the improvement in older engines can also be helpful. High-pressure turbine nozzles, upgraded gas turbines, and steam injection can greatly assist in minimizing pollution. Another requirement is to design engine which reduces the fuel combustion as fuel burn also contributes heavily to air pollution. Moreover, light aircraft can be run on lower-compression engines which may be operated on mogas (Motor Gasoline) mogas does not contain tetra-ethyl lead (TEL). thus, using mogas instead of avgas will be helpful in minimizing air pollution.Another way of reducing environmental pollution caused by aviation is by improving the operational efficiency of the aircraft i.e. by increasing the number of passengers in each flight. This will reduce emissions per passenger. The reduction in taxi time may also be helpful in reducing pollution. Pollution may also be reduced by reducing energy output during landing, takeoff and taxi time.