A room air cleaner can be effective in reducing levels of SO2 and/or PM2.5 from the air. Those living close to the volcano need protection from both SO2 and PM2.5, so will need a specialized air cleaner which has both a HEPA (PM2.5) filter and an acid gas (SO2) filter. Those living further from the vent can use an air cleaner designed to filter fine particles only (HEPA) since they are not exposed to substantial amounts of SO2.
Quality room air cleaners can be expensive and are designed for a room that can be closed-off from the rest of the house and the outdoors. Periodic filter replacement and other maintenance is required for air cleaners to perform as designed.
Guide to Air Cleaners in the Home – Background information for selection of the home air cleaner that may be best for addressing specific types of contaminants.
Certification program for air cleaners that filter particulates, and information on many brands and models of air cleaners.