How does EPA propose the most restrictive standards ever issued for particulate matter and claim that 99% of all U.S counties will be in attainment without any further action? 

Yes, like all magic tricks it is based on sleight of hand.  First of all, over the last several years EPA has launched a parade of new regulations (Utility MACT, on - and off - road diesel rules, boiler MACT, cement MACT, and other air toxics) allegedly to address very specific industry emissions but which in fact all focus on particulate matter.  Therefore, when it came time to issue the proposed particulate matter regulation, EPA did not have the need to reduce any additional particulate matter. All the reductions had been made by the regulations already issued. The result of the new particulate matter rule is a non-event and EPA can claim it can protect public health without any additional cost or local effort. 

Why should it matter how EPA protects our health from dangerous pollutants?  It matters a great deal to the regulated community and the states that are trying to develop jobs for their citizens.  Look at the manner in which EPA proceeded: it went after very specific industries and it imposed huge costs on these industries across the nation (e.g. coal fired power plants up to $100 billion in costs; paper mills up to $5 billion in costs; and such high costs on cement plants that 20% will shut down rather than comply).  These regulations are causing the loss of hundreds of thousands of jobs, and have made specific industries pay the entire price of emission reductions.

Had EPA proceeded with particulate matter reductions as it has for decades, by issuing the same particulate matter regulation that it did today without all the redundant industry-specific regulations, it would have been up to the states to determine the reductions needed to achieve EPA’s standard.  The states needing to reduce particulate matter would have many options ranging from transportation controls to bike paths to industry-specific requirements on all industry within its territory.  In short, the state -  not EPA - would determine how to balance its environment and economy.

When looking at the whole picture, EPA’s actions have only served to pick winners and losers, and diminish the role of the states.