You should consider wearing a high-filtration mask when you are in a crowded public, indoor space and cannot easily keep social distance from other people, especially if there isn't good ventilation or air circulation. On February 25, 2022, the Centers for Disease Control and Prevention revised guidance on masking, recommending that people in high-risk areas wear masks indoors, while people in medium-risk areas should consider wearing a mask if they are immunocompromised or at risk of severe illness, or if they live with or interact with these people. The CDC also said that people in low-risk areas may still wear a mask based on personal preference. In situations where you might wear a mask, a high-filtration mask provides the best protection for you and others against the highly contagious Omicron variant.