On January 6, 2023, after carefully reviewing the most recent available scientific evidence and technical information, and consulting with the Agency’s independent scientific advisors, EPA announced its proposed decision to revise the primary (health-based) annual PM2.5 standard from its current level of 12.0 µg/m3 to within the range of 9.0 to 10.0 µg/m3. EPA also proposed not to change the current:
- secondary (welfare-based) annual PM2.5 standard,
- primary and secondary 24-hour PM2.5 standards, and
- primary and secondary PM10 standards.
In addition, EPA proposed revisions to other key aspects related to the PM NAAQS, including revisions to the Air Quality Index (AQI) and monitoring requirements.