According to a Brookings Institution study of the nation's 100 largest metropolitan areas, Lexington ranked number 100 as the worst for carbon emission.

Los Angeles and New York were ranked in the top five for having the least carbon footprints across the nation. The rankings were based highly on carbon usage per capita.

There are a number of contributing factors to Lexington's ranking. Urban sprawl is a major factor and the use of public transportation is low compared to denser cities.

Also, Lexington's energy source is primarily coal. Being a mid-latitude state, heating and cooling systems are used nearly year-round.

The average Lexington resident was responsible for putting 3.46 metric tons of carbon emissions in the the atmosphere in 2005. The average footprint for all metro areas was 2.24 tons.

Other cities in the five worst include the Cincinnati-Northern Kentucky area, which came in at number 98, and Louisville, which weighed in at number 96.