SIPs for the 9 µg/m3 PM2.5 Standard
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Introduction
The Clean Air Act (Act) requires the U.S. Environmental Protection Agency (U.S. EPA) to set health-based national ambient air quality standards (NAAQS or standards) for numerous pollutants, including fine particulate matter (PM2.5). On February 7, 2024, U.S. EPA strengthened the annual PM2.5 standard from 12.0 micrograms per cubic meter (µg/m3) to 9.0 μg/m3, based on an integrated assessment of an extensive body of new scientific evidence, which improved the body of knowledge regarding PM2.5-related health effects.
Designations: Public Hearing on January 23, 2025
The first step in addressing the 9 μg/m3 standard is designating regions of the State as either attaining or not attaining the new standard. On December 13, 2024, CARB published a Public Notice announcing that CARB will hold a public hearing on January 23, 2025, to consider staff recommendations for designations and nonattainment area boundaries. Staff are recommending nine nonattainment areas for the 9 μg/m3 standard, as detailed in the Staff Report. The areas are as follows: portion of Plumas County, portion of Mendocino County, portion of Feather River Air Quality Management District, San Francisco Bay Area Air Basin, Sacramento County, San Joaquin Valley Air Basin, South Coast Air Basin, San Diego County, and portion of Imperial County.
For more information on designations, please see CARB’s designations page.
Workshops
Workshop #2: December 5, 2024
CARB held a public workshop on the evening of Thursday, December 5, 2024, related to nonattainment designation recommendations and planning efforts for the 9 μg/m3 PM2.5 standard. CARB staff discussed each nonattainment area recommendation along with proposed emission inventory improvements for the future SIPs. Materials from this workshop are available below.
- Public Notice (English) (Spanish)
- Presentation (English) (Spanish)
- Recording (will post after the workshop)
Workshop #1: September 25, 2024
CARB previously held a public workshop on the evening of Wednesday, September 25, 2024, to kick off the SIP planning efforts for the 9 µg/m3 PM2.5 standard. The workshop was the first in a series exploring various aspects of planning for the 9 µg/m3 PM2.5 standard which the State is required to undertake pursuant to the Act. Materials from this workshop are available below.
- Public Notice (English) (Spanish)
- Presentation (English) (Spanish)
- Recording (English and Spanish channels available)
Resources
For more information, please see the below links to CARB- and U.S. EPA-created resources on PM2.5 and the 9 ug/m3 PM2.5 standard.