This is the result of the "Dust & Scratches" filter. The noise has greatly been reduced.



There is another Photoshop filter that can be used to reduce noise called "Despeckle", it is pretty similar to "Dust & Scratches", but works on a lower level. You don't get to pick any settings, you just apply it as many times as you need to. The more you apply it, the more noise will be removed. To access it, go to the "Filter" menu, slide down to "Noise" and slide over and down to "Despeckle".



Here's the result of one application of "Despeckle" on this image.



Here's the result of two applications of "Despeckle" on this image.



Here's the result of three applications of "Despeckle" on this image. This is about enough and I think I'll stop here. The noise has been significantly reduced.