The Carbon Footprint of the American Thoracic Society Meeting To the Editor: The American Thoracic Society (ATS) International Conference held in San Diego in May 2006 was attended by approximately 15,000 delegates, the majority of whom traveled by air. The environmental impact of such a large international meeting is likely to be significant, but has not been previously studied. The carbon dioxide emissions were calculated for air travel to and from San Diego using the attendance figures for ATS 2006 divided by an estimate of the distance traveled from the country or state of origin. All delegates were assumed to have traveled from the largest city in their country, state, or province. Connecting flights were determined using a commercial website ( and the overall journey time of the shortest duration was selected. Carbon dioxide emissions were calculated according to a widely accepted model (1), assuming travel on a Boeing 737 for journeys of 2,000 km or less, and a Boeing 747 for journeys greater than 2,000 km. As a comparison, calculations using the 2006 delegate information were made for return travel to the five other ATS host cities since 2000 (Atlanta, Orlando, Seattle, San Francisco, and Toronto).

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