EPA is proposing once again to tighten the National Ambient Air Quality Standard (NAAQS) for PM2.5 for the reasons summarized by EPA, below. What is PM2.5 and does it kill people? Fine particulate matter in outdoor air, also called PM2.5, is the most toxic substance known to man. PM2.5 is responsible for 8 million, or … Continue reading PM2.5: Mass Killer or Mass Fraud?