A dirty crawl space should not be ignored, since rodent droppings, urine

https://johnnymvnk630.rivetgarden.com/posts/what-to-do-if-you-hear-scratching-in-your-ceiling-3

A dirty crawl space should not be ignored, since rodent droppings, urine, and nesting debris are biological contaminants that can affect the air inside your home.