Can anyone explain how I can hide product attribute filters if there are no products with that attribute? 

What I mean by that is: If I have created website categories for example like Apparel and tools. Within the Apparel category there are products that have an attribute assigned to them called "Type" which has values of hats, gloves, pants, shirts. Within the tools category there are products that use the same attribute "Type" but have values of hammer, saw, drill. If I go into the tools category on the website how do I make it so the hats, gloves, pants, and shirts attribute values are not visible under the attribute "Type" unless someone adds a product to the tools category that has one of those assigned to it?