Poly vs. Dirt Kickback

[DerbyCat]

Knowing that many of the Derby horses are training at Keeneland and have had several races on the poly surface, will the kickback from a dirt track possibly affect some horses on May 5th negatively? If so, who might it cause problems for?

Is there much of a difference between the two surfaces for a horse having it kicked into his face? This is an angle that has me curious.... looking forward to your thoughts.