Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

Contact Us Search: All EPA Region 9

• You are here: EPA Home
• Region 9
• Air
• Air Quality Trends
• Carbon Monoxide Concentrations (1970-2003)

Carbon Monoxide Concentrations
Air Quality Trends (1970-2003)

Air Quality Trends Quick Finder
Air Quality Trends Home Carbon Monoxide (CO) Lead (Pb)	Nitrogen Dioxide (NO2) Ozone (O3) Particulate Matter (PM2.5)	Particulate Matter (PM10) Sulfur Dioxide (SO2)

"Design Value" - National 8-hour Standard
Highest Second High Day over Two Years

Region 9 Topics and Programs | A-Z Index

Local Navigation

• Region 9 Home
• Region 9 Air Home

---

• Today's Air Quality
• Air Quality Maps
• Air Trends
• Air Permits
• Air Plan Actions
• Arizona
• California
• Nevada
• Navajo Nation
• SIP Rule Collection
• Alternative Test Methods
• Air Delegations
• State & Local Contacts
• About Us
• Air Archive

• EPA Home
• Privacy and Security Notice
• Contact Us