If you're in the Western US/Canada, they're very helpful during the (more frequent and increasingly severe) fire and smoke seasons. See this pic of a filter aft

If you're in the Western US/Canada, they're very helpful during the (more frequent and increasingly severe) fire and smoke seasons. See this pic of a filter after 6 days: https://www.reddit.com/r/pics/comments/9xroh4/air_filter_after_6_days_of_use_near_the_camp_fire/ https://www.reddit.com/r/pics/comments/9xroh4/air_filter_aft... They're also good if you cook with oil indoors.