Not true. One of the major sources of matter causing global dimming is aircraft exhausts. Material at very high altitudes, reflecting, not absorbing, sunlight!
You might recall all airline traffic in the USA was grounded for a number of days following 911.
This was a scenario scientists had thought about but knew would be impossible to implement. Unbelievably, they got their chance.
Now, you may like to look into the unusual weather observations and occurrences which occurred in the days when the planes stopped flying.
Here you go http://www.youtube.com/watch?v=bLfBXRPoHRc
