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The PM-10 and PM-2.5 Standards

There are presently 37 areas that violate the current PM-10 standard. The form of the PM-2.5 standard requires that the 3-year average (rounded to the nearest 0.1 ug/m3) of the annual means from single monitors or the average of multiple monitors must be at or below the level of the annual standard and the 3-year average (rounded to the nearest 1 ug/m3) of the ninety-eighth percentile values at each monitor cannot exceed the level of the daily standard. In determining attainment of the annual average standard, an area may choose to use either the spatially averaged concentrations across all population-oriented monitors or it may use the highest 3-year average based on individual monitors. The annual PM-2.5 standard (2012) is 12 ug/m3. The level of the 24-hour PM-2.5 standard (2006) is 35 micrograms per cubic meter (µg/m3). Maps of the EPA's PM-10 and PM-2.5 designations for nonattainment can be reviewed by clicking here.

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