Figurative languages are those literary techniques used by writers to provide more color in their writings. These techniques allow the writers to provide more in-depth meaning or image to their works by using numerous mechanisms such as hyperbole, simile, metaphor, personification, etc among others.
The statement<em> "the air both day and night felt like breathing through a dishrag"</em> from the novel <em>Cold Mountain </em>by Charles Frazier is a <em>simile</em>. It compares two unlike things, in this case, the air and breathing through a dishrag.