Being a safety professional, this is probably the WORST way to clean a respirator. The rubbing alcohol will soon make the rubber/silicone parts very stiff and brittle.
The best way to clean them is to remove the filters, wash the entire respirator including straps in a mild solution of dish soap and water (use a soft brush if needed), rinse in clean water, dip in a 10ppm solution of bleach & water (one 'glug' of bleach in 5 gal. clean water), again rinse in clean water and hang in a clean place to dry. After it is dry, install NEW cartridges and store in a clean location or in a zip lock bag. The soap & water cleans it and the bleach disinfects it. Be safe out there.