Dust is everywhere in the environment, unless one lives in outer space. It is impossible to find a used lens without dust, and even new lenses have some dust. Dust is out of the photographic plane and simply will not affect a photograph.
Olympus photographers who are looking for a lens to capture outdoor sporting events, wildlife, or even portraits will find the Sigma AF Zoom to be a practical choice. There is always room between the field of play and the viewing audience, enough to accommodate the 3 ft minimum shooting distance of this 75-200 mm f/3.8 lens.