Well at least we are number one at something--Atlanta Named Most Toxic U.S. City,

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Las Vegas has far from a clean reputation, but in Forbes' list of America's Most Toxic Cities, Las Vegas is named the least toxic of 40 major metropolitan areas.

Forbes ranked the cities based on the number of Superfund sites in the principal city, number of facilities that release toxic chemicals, amount of toxic chemicals released in the area and air quality ranking.

Following Las Vegas as the top 10 least toxic cities are Sacramento, Riverside, Austin, Seattle, San Diego, Virginia Beach, San Jose, New York and Phoenix.

Surprised to see a major city like New York in the top ten cleanest? Forbes explains:

Crowded urban areas are often thought of as the most polluted, but the latter isn't always caused by the former. While the Atlanta metro area takes top honors for toxicity, don't blame the city alone. The Atlanta metro includes the cities of Sandy Springs and Marietta, the sites of chemical plants, metal coaters and concrete factories. The cities have toxic-release levels equal at or higher than those Atlanta, in spite of populations that are 15% and 13% the size of Atlanta's, respectively.

The title of most toxic city goes to Atlanta, followed by Detroit, Houston, Chicago, Philadelphia, Cleveland, Los Angeles, Jacksonville, Baltimore and Portland.

In some cases it's not the main city itself that is to blame for poor air or dirty water. As Forbes explains, much of the pollution for some cities comes from factories and plants in surrounding areas.

"...while the Philadelphia metro area is our fourth most toxic area, the City of Brotherly Love doesn't hold the bulk of the blame for the pollution. Factories in smaller Wilmington, Del., in the same metro area, reported releasing 57% more pounds of toxins than Philadelphia in 2007. Wilmington houses a Pepsi bottler and General Motors assembly plant, as well as the headquarters of chemical company Dupont."

The most toxic cities:
1. Atlanta-Sandy Springs-Marietta
2. Detroit-Warren-Livonia
3. Chicago-Naperville-Joliet
4. Houston-Sugar Land-Baytown
5. Philadelphia-Camden-Wilmington
6. Cleveland-Elyria-Mentor
7. Los Angeles-Long Beach-Santa Ana
8. Jacksonville
9. Baltimore-Towson
10. Portland-Vancouver-Beaverton

The least toxic cities:
1. Las Vegas-Paradise
2. Sacramento--Arden-Arcade--Roseville
3. Riverside-San Bernardino-Ontario
4. Austin-Round Rock
5. Seattle-Tacoma-Bellevue
6. San Diego-Carlsbad-San Marcos
7. Virginia Beach-Norfolk-Newport News
8. San Jose-Sunnyvale-Santa Clara
9. New York-Northern New Jersey-Long Island
10. Phoenix-Mesa-Scottsdale