US president Barack Obama has pushed through legislation that will put a cap on ground-level air pollutants.
From January 2012, the Environmental Protection Agency (EPA) will enforce the new cap, known as the Cross-State Air Pollution Rule (CSAPR).
CSAPR will limit the amount of nitrogen oxides and sulphur dioxide. The legislation is expected to dramatically improve
air quality in the states and make coal-fired power stations far less economically viable.
Implementation of the new cap will come as a surprise to many as the original climate bill - introduced last year - was thrown out by a seemingly pro-coal senate.
As a result of the pollutant cap, the US energy sector is expected to shift towards natural gas and renewable energies - such as wind and solar power.
Obama has come under fire from Texan senators in particular, who want pollution cap enforcement to be delayed.
The state is hoping to build nine new coal-fired power stations in the coming years.
Posted by Lauren Steadman