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
    • Cancer
    • 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
    • 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. Stationary Sources of Air Pollution

Clarification of 40 CFR Part 63, Subpart LL Requirements Applicable to Potlines During Startup Periods

Letter from EPA Office of Air Quality Planning and Standards to Henry V. Nickel and William L Wehrum of Hunton & Williams setting forth EPA's interpretations of regulatory requirements applicable to potlines at primary aluminum reduction plants during startup under 40 CFR part 63, subpart LL. 

  • Clarification of 40 CFR Part 63, Subpart LL Requirements Applicable to Potlines During Startup Periods (pdf) (1.44 MB, June 17, 2010)

Stationary Sources of Air Pollution

  • Regulations
    • Industry Sector Groups
    • National Emission Standards for Hazardous Air Pollutants (NESHAP)
      • Area Source Standards
      • Risk and Technology Review Status
    • New Source Performance Standards
    • Good Neighbor Plan for the 2015 Ozone National Ambient Air Quality Standards
  • Small Business Assistance Program
Contact Us About Stationary Sources of Air Pollution
Contact Us About Stationary Sources of Air Pollution to ask a question, provide feedback, or report a problem.
Last updated on June 24, 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.