I was thinking about this as an a/c-less option to defrost and then thought silicosis...
Silicosis - Wikipedia, the free encyclopedia
Silicosis is due to deposition of fine respirable dust (less than 10 micrometers in diameter) containing crystalline silicon dioxide in the form of alpha-quartz, cristobalite, or tridymite.
Looks like a simple hepa filter may work. Could be overkill but being overly safe seems like a good precaution...