Based on water availability, water potability, waste removal, sewage, air pollution and traffic congestion, the Canada's Calgary captured the No. 1 spot, with Ottawa; Helsinki, Finland and Wellington, New Zealand rounding out the top five.
Here are other cities in the U.S. and around the world that made the list and why:
Other U.S. cities to make the list include Pittsburgh at 13th, Washington, D.C. at 23rd, Boston at 25th, Philadelphia at 34th, and St. Louis squeezing in at 43rd.
Maybe the reason Mercer's list is missing U.S. cities like San Francisco and Denver that have built impressive eco-reputations is because the study doesn't consider several key metrics necessary for determining a city's earth-friendliness: recycling centers, waste-removal programs, and land designated for public parks and conservation organizations. It also seems to conflict with environmental studies conducted by other eco-organizations.
A study produced last year by the American Lung Association names Pittsburgh -- a town that shares a five-way tie (with Montreal, Canada; Nuremberg, Germany; Auckland, New Zealand; and Bern, Switzerland) for the No. 13 slot on Mercer's survey -- as one of the top five U.S. cities with the most air pollution. St. Louis comes in at No. 9.
Last November, Forbes Magazine ranked the Philadelphia-Camden-Wilmington metro area as the fifth most toxic area of the country, due in large part to the fact that the it releases more than 24 million pounds of toxic chemicals into the atmosphere each year. Yet Philadelphia appears on Mercer's list as the 34th best eco-city.
Mercer's study appears in tandem with the company's list of the top 50 cities worldwide with the highest quality of life. Based on criteria ranging from availability of food to access to public transportation, the survey is European dominated, with Honolulu coming in at No. 31, San Francisco tying for 32nd, and Boston, Washington D.C., Chicago, New York City, Seattle, and Adelaide, Australia all claiming spots in the bottom 15.
Instead of trusting the experts on this one, we're simply going to turn it over to the people who live there. What do you think readers? Which U.S. city has the best quality of life?
More on AOL Real Estate:
See apartments for rent in your area.
Looking for a new home? See "Should You Rent or Buy?"
Want to learn more about home buying and home finance? If so, you won't want to miss
our online discussion with industry experts,
"What Works Now: Smart Moves When Buying a Home,"
created by AOL Real Estate in participation with Bank of America Home Loans.
Watch it now on AOL Real Estate.