Skip to main content
U.S. flag

An official website of the United States government

Here’s how you know

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

HTTPS

Secure .gov websites use HTTPS
A lock (LockA locked padlock) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

    • Environmental Topics
    • Air
    • Bed Bugs
    • Chemicals, Toxics, and Pesticide
    • Emergency Response
    • Environmental Information by Location
    • Health
    • Land, Waste, and Cleanup
    • Lead
    • Mold
    • Radon
    • Research
    • Science Topics
    • Water Topics
    • A-Z Topic Index
    • Laws & Regulations
    • By Business Sector
    • By Topic
    • Compliance
    • Enforcement
    • Guidance
    • Laws and Executive Orders
    • Regulations
    • Report a Violation
    • Environmental Violations
    • Fraud, Waste or Abuse
    • About EPA
    • Our Mission and What We Do
    • Headquarters Offices
    • Regional Offices
    • Labs and Research Centers
    • Planning, Budget, and Results
    • Organization Chart
    • EPA History

Breadcrumb

  1. Home
  2. EPA in California
  3. Moss Landing Vistra Battery Fire
  4. Frequently Asked Questions

Moss Landing Air: What were the results of EPA's air monitoring from January 17 to 20?

Return to: Frequently Asked Questions

  • Particulate matter (PM2.5 and PM10)
    EPA’s monitoring showed concentrations of particulate matter to be consistent with the air quality index throughout the Monterey Bay and San Francisco Bay regions, with no measurements exceeding the moderate air quality level.
  • Hydrogen fluoride gas
    Hydrogen fluoride gas was measured at one second intervals and there were no exceedances of California’s human health standards.

Post-Fire

  • The initial fire subsided on January 18, 2025.
  • On January 20, after smoke subsided, EPA consulted with Monterey County and transferred air monitoring stations to Vistra.
  • Vistra continued air monitoring at the property and in the community. The data is being provided to the county.

Related Questions

  • Moss Landing Air: What air monitoring activities did you do during the January fire response?
  • Moss Landing Air: What did you test for during the fire?
  • Moss Landing Air: What air monitoring technology did you use?
  • Moss Landing Air: Are you requiring any air monitoring or sampling during Vistra’s battery removal work?
  • Moss Landing Air: Is there a difference between air monitoring and air sampling?
  • Moss Landing Air: What particulate sizes did EPA monitor during the initial response in January?
  • Moss Landing Air: Can you detect nanoparticles in the air with the instrumentation you used during the initial response?
  • Moss Landing Air: What happened with the spike in particulate matter at air monitoring station 9 the morning of January 18, which resulted in a 1.275 mg/m3 reading for PM10?

EPA in California

  • Topics and Resources
    • California Bioresources Alliance Symposia
      • 2024
      • 2023
      • 2022
      • 2021
      • 2020
      • 2019
      • 2018
      • 2017
      • 2016
    • Central Metal Site Investigation
      • Frequently Asked Questions (FAQs)
      • Investigación del sitio de Central Metal
      • Preguntas Frecuentes
    • Former Exide Battery Recycling Facility
      • En español
      • Archived Updates
    • Kettleman Hills
      • Permit and Supporting Documents
  • Moss Landing Vistra Battery Fire
    • Response Timeline
    • Frequently Asked Questions
    • Photographs
    • Register for Email Updates
  • Incendio de la batería Vistra en Moss Landing
    • Cronograma de respuesta
    • Preguntas frecuentes
    • Fotografías
    • Únase a la lista de distribución por correo electrónico
Contact Us about EPA in California
Contact Us about EPA in California to ask a question, provide feedback, or report a problem.
Last updated on September 29, 2025
  • Assistance
  • Spanish
  • Arabic
  • Chinese (simplified)
  • Chinese (traditional)
  • French
  • Haitian Creole
  • Korean
  • Portuguese
  • Russian
  • Tagalog
  • Vietnamese
United States Environmental Protection Agency

Discover.

  • Accessibility Statement
  • Budget & Performance
  • Contracting
  • EPA www Web Snapshot
  • Grants
  • No FEAR Act Data
  • Plain Writing
  • Privacy
  • Privacy and Security Notice

Connect.

  • Data
  • Inspector General
  • Jobs
  • Newsroom
  • Regulations.gov
  • Subscribe
  • USA.gov
  • White House

Ask.

  • Contact EPA
  • EPA Disclaimers
  • Hotlines
  • FOIA Requests
  • Frequent Questions
  • Site Feedback

Follow.