EPA originally sought to limit PM2.5 from 15 micrograms per cubic meter to 12 micrograms per cubic meter, according to an e-mail The Washington Post retrieved between the Office of Management and Budget (OMB) and EPA officials.
However, OMB directed the EPA to make the limit between 12 and 13 micrograms per cubic meter of air, allowing power plants slightly more leniency in limiting PM2.5.
EPA plans to issue the final standards by Dec.14, 2012.
For more information on the proposed rule, click here.
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