A clean grease filter is vital to a kitchen’s air quality and fire safety. Depending on your cooking style and how often you cook, you should clean a residential range hood filter every one to three months. Clean a commercial hood grease filter at least weekly. Many microwaves also have metal grease filters that should be cleaned at least every four months. To clean a grease filter, soak it for ten minutes in a cleaning solution. Scrub it with a soft-bristled brush, and use a toothbrush to get into tight crevices. Rinse, dry, then reinstall it, and enjoy the benefits of a squeaky clean grease filter.