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

https://alexisvbiz385.readspirex.com/posts/what-to-do-if-you-hear-scratching-in-your-ceiling-2

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.