This particular aircraft starts to smoke when the ignition is turned on because the fuel does not burn throughout completely, therefore there is this smoke that comes out and it damages our atmosphere. There are millions of airplanes that start up daily and pollute our air.
Here is the pic:

What airplane is that ?

EDIT:
[glb]THIS IS 50% REAL, 50% FS PICTURE !!!
For those who are wondering how come . . . follow down the topic . . . [/glb]