Dust louvers clean using a dry soft bristled paint brush. The bristles will slide between each louver and remove dust from the slanted surfaces. If a brush is not available, wrap a rag around the end of a ruler and insert it between each louver. This way will take longer than using a brush, but the louvers will come out just as clean and dust free.
Mix up a small bucket of soapy water solution. Dip the brush into the solution and wash the louvers, just like dusting them, to remove built-on dirt and grime. A ruler with a rag wrapped around the end can also be used in this same way. Again, it will take longer, but the louvers will get just as clean.
Rinse the louvers with fresh water by dipping using either the brush or the rag-wrapped ruler into fresh water and running them between the louvers.