SAN FRANCISCO (CBS SF/AP) – In a study comparing the carbon footprint of rich and low-income households in the United States, San Francisco’s Mission Bay neighborhood stood out as the greenest zip code and California was the greenest state in the country.

The study was published an article titled, ‘The carbon footprint of household energy use in the United States,’ in the Proceedings of the National Academy of Science in the United States of America.

Scientists studied 93 million households in the nation and found rich Americans produce nearly 25% more heat-trapping gases than poorer people at home.

In a state-by-state comparison, researchers found that California was the greenest state with 2,715 pounds of greenhouse gas per person. Oregon, New York, Utah, Washington, Rhode Island, Massachusetts, Idaho, Connecticut and New Mexico follow on the list of the 10 cleanest states.

The study’s 25 cleanest zip code for residential greenhouse gas emissions was Mission Bay, in San Francisco, a white collar area with relatively new housing stock, where the average person produces only 1,320 pounds a year.

The zip codes that produced the most gas are scattered across Colorado, North Carolina, Pennsylvania, Alabama, Louisiana, Wyoming, Maryland, West Virginia, Minnesota, Missouri, Georgia, Arkansas, Indiana and Utah.

The zip code that produced the most greenhouse gas per person was in the mountains of western Boulder County, Colorado, where the 23,811 pounds per person is 18 times higher than in the San Francisco zip code.