The US Environmental Protection Agency (EPA) has announced a final rule to address greenhouse gas (GHG) emissions from the largest stationary sources.

Under the new Clean Air Act, permits will be required for all new facilities emitting at least 100,000t per year (tpy) of GHG emissions, and also for modifications at existing facilities that would increase emissions by at least 75,000 tpy.

The permits must demonstrate the use of best available control technologies to minimise GHG emission increases when facilities are constructed or significantly modified, the EPA said.

EPA expects to receive about 900 additional permitting actions covering new sources and modifications to existing sources will be subject to review each year.

The EPA also estimates 550 sources will need to obtain operating permits for the first time because of their GHG emissions.

The act is expected to come into effect from July 2011.