The Dust & Scratches filter is ideal for removing lots of tiny specks of dust in one magical hit
For old photos covered in tiny white specks, the Dust & Scratches Noise filter will clean up your image in one hit.
Radius: The Radius amount was set to 2px for this image below. Look to remove the majority, it not all, of the spots by increasing the slider. One pixel may do the trick.
Threshold: Use Threshold to bring back details that were lost after using Radius. Start with 0 and work your way up.