AP reported that a proposal to expand the world's largest open pit copper mine and keep it operating for another decade could take an important step forward Wednesday if Utah air quality regulators allow increased emissions from the operation.

But opponents are worried increased emissions will further foul the air along the urban Wasatch Front, especially during the winter when the region has some of the most polluted air in the country.

Ms Jana Kettering company spokeswoman said that the Air Quality Board's approval for increased emissions is needed to extend the usefulness of the Kennecott copper mine until 2028 adding almost a decade to its current projected life. The Cornerstone Project would widen the mine by about 1,000 feet and deepen it by about 300 feet.

Ms Kettering said that the approval along with an operations expansion, would allow the company to invest in other initiatives that will result in an overall decrease of emissions from a mine that is about Q3 of a mile deep and 25 miles southwest of Salt Lake City.

The spokeswoman said that those include plans to convert three existing coal-fired power plants to natural gas. Kettering said the overall decrease in emissions would be about 9% but only if parent company Rio Tinto is assured that their investments will pay off.

Mr Cherise Udell president of Utah Moms for Clean Air said that those decreases are only on paper and nothing more than fancy bookkeeping.

(Sourced from Associated Press)