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.

Emergency

This is not the current EPA website. To navigate to the current EPA website, please go to www.epa.gov. This website is historical material reflecting the EPA website as it existed on January 19, 2025. This website is no longer updated and links to external websites and some internal pages may not work. More information »

    • Environmental Topics
    • Air
    • Bed Bugs
    • Cancer
    • Chemicals, Toxics, and Pesticide
    • Climate Change
    • Emergency Response
    • Environmental Information by Location
    • Environmental Justice
    • Greener Living
    • 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
    • Staff Directory

Carbon Monoxide (CO) Pollution in Outdoor Air

  • CO in Outdoor Air

    CO is a colorless, odorless gas that can be harmful when inhaled in large amounts. 

Carbon Monoxide Basics

  • What is CO?
  • What are the harmful effects of CO?
  • What is being done to reduce CO pollution in outdoor air?

Setting and Reviewing the Standards

  • What are CO standards?
  • How are the standards developed and reviewed?
  • What scientific and technical information supports reviews?

Implementing the Standards

  • Designations: how do we know if an area is not meeting CO standards?
  • What are the state implementation plan (SIP) requirements?
  • How do states develop SIPs and start attaining the standards?

Other Common Air Pollutants

  • Ground-level Ozone
  • Particulate Matter (PM)
  • Lead (Pb)
  • Sulfur Dioxide (SO2)
  • Nitrogen Dioxide (NO2)

See information on all criteria air pollutants.

Contact Us about Carbon Monoxide (CO) Pollution to ask a question, provide feedback, or report a problem.
Last updated on November 14, 2024
  • Assistance
  • Ayuda
  • Arabic
  • Chinese (simplified)
  • Chinese (traditional)
  • Aide
  • Asistans
  • Korean
  • Assistência
  • Russian
  • Tulong
  • 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

Follow.