For a general sense of dust:
* Dust: This is the most straightforward option.
* Dustiness: This emphasizes the quality of being dusty.
* Powder: This works well for fine dust.
For a specific thing that is dusty:
* Surface: For a dusty tabletop, floor, etc.
* Object: For a dusty book, vase, etc.
* Room: For a dusty room.
* Area: For a dusty region or landscape.
For a metaphorical use of "dusty":
* Memories: For old, forgotten memories.
* Past: For a forgotten or bygone era.
* History: For a past that feels distant and unclear.
Examples:
* "The room was filled with dust."
* "The dustiness of the attic was overwhelming."
* "The antique lamp was covered in a thick layer of powder."
* "The surface of the old piano was covered in dust."
* "The old photograph held a dusty memory of my childhood."
Choose the noun that best fits the context and what you want to emphasize.