You are hard to find in the waste.
Prerequisites: Dex 13, Hide 5 ranks.Benefit: You have an inborn sense of where to lurk without being seen, gaining a +2 bonus on your Hide checks and reducing the distance within which creatures can detect you by scent to 10 feet (20 feet if upwind, 5 feet if downwind). If you are in an area covered in a layer of at least 1 inch of ash, dust, loose earth, or sand, you gain an additional +2 bonus on Hide checks, a +2 bonus on Move Silently checks, and a creature can detect you by scent only if it is within 5 feet (pinpointing your location as normal).
See Determining Loose Soil for finding the chance of sufficient ash, dust, grit, loose earth, or sand existing to use the latter part of this feat.
Source: Sandstorm, page 53.