How do you know if a musty smell in a house is caused by mold or just high humidity?

Hi everyone,

I recently started wondering about musty smells in a house. If there isn’t any obvious water leak or visible mold, how can you tell whether the smell is simply from high humidity or if there could actually be mold growing somewhere?

Are there certain areas of the house that should be checked first, such as the crawl space, attic, HVAC system, or around windows?

Would you recommend getting the humidity level checked first, or having the house inspected for moisture/mold?

I’d appreciate any advice from homeowners who have dealt with something similar.

Thanks!