The Colorado Air Pollution Control Division projects that in 2010 oil- and gas-related sources will comprise 69% of the emissions of volatile organic compounds (VOCs) in areas of Colorado outside of the Denver area and El Paso and Pueblo Counties. This is an increase from 35% in 2005.
A recent article in the Ft. Worth Star-Telegram discussed air pollution produced by natural gas extraction in Texas and and an upcoming report on the topic. This report will likely have information that is applicable elsewhere and we're looking forward to seeing it.