With #AirQuality #AirPollution at unhealthy levels in the #BayArea region I thought it might be helpful to outline what it means, why you should care, and some tips on what you should be doing.👇👇👇 Fine particulate matter or “PM2.5” are tiny particles suspended in the air that much smaller than the width of a human hair. When you breathe these particles enter your respiratory tract and end up in your lungs.