Summary of EPA Proposal to Revise the PM NAAQS

andDraft WRAP Technical

Comments

PM2.5

• Annual primary standard currently 15 ug/m3

– No change in the proposal– Taking comment on 13 or 14 ug/m3

• 24-hr primary standard currently 65 ug/m3

– Proposal would reduce to 35 ug/m3

– Taking comment on 30-35 ug/m3

• Secondary standards would be equivalent– Taking comment on urban visibility standard of

20-30 ug/m3 averaged over 4-8 daylight hours

PM2.5

• Draft WRAP technical comments support secondary standard for urban visibility– Would have direct benefits to Class I areas

impacted by urban areas

PM10

• Proposal would revoke annual standard in all areas

• Proposal would revoke 24-hr standard in all areas except in urbanized areas where:– Population is at least 100,000, and– At least one monitor is violating the standard

• 24-hr standard would remain in areas above until PM10-2.5 designations occur

Locations where EPA proposes to retain the 24-hr PM10 standard.

Current PM10 nonattainment areas where EPA proposed to revoke the 24-hr standard.

69 PM10 nonattainment and maintenance areas in the WRAP region.

PM10

• EPA taking comment on retaining 24-hr standard in areas with population less than 100,000

• Draft WRAP technical comments support elimination of 100,000 population distinction

PM10-2.5

• PM10-2.5 defined as:

– Any ambient mix of PM10-2.5 that is dominated by resuspended dust from high-density traffic on paved roads and PM generated by industrial sources and construction sources.

– This definition excludes any ambient mix of PM10-2.5 that is dominated by rural windblown dust and soils and PM generated by agricultural and mining sources.

– Agricultural sources, mining sources, and other similar sources of crustal material shall not be subject to control in meeting this standard.

PM10-2.5

• The indicator is not defined or limited to any specific geographic area, but includes a mix of PM10-2.5 in any location that is dominated by these sources.

• 24-hr primary standard set at 70 ug/m3

– 3-year average of 98th percentile

• No annual primary standard• Secondary standards equivalent to primary

– Does this protect visibility?

PM10-2.5

• EPA taking comment on:– Alternative approaches for selecting level of

PM10-2.5 standard

– Selecting an unqualified PM10-2.5 indicator

– Alternative approaches to retaining the 24-hr PM10 standard

Draft WRAP Technical Comments on PM10-2.5 Standard

• Eliminate distinction of urban PM10-2.5

• Eliminate exemption for ag, mining, and rural windblown dust– Without eliminating these two provisions, the

ability to make reasonable visibility progress in Class I areas will be jeopardized

• EPA should adopt a 24-hr PM10-2.5 standard in the range of 50-135 ug/m3

3

The percentage of sampling days when dust dominated aerosol light extinction is as high as ~ 50 –70% in some of the sites. “Dominated” means that it caused more light extinction than any of the other major categories -- SO4, NOx, EC, and OC.

Percentage of IMPROVE sample days between 1997 and 2002 when hazefrom dust (coarse mass plus fine soil) is the largest component.

Annual PM10-2.5 concentration from the IMPROVE network for 2004.

Modeled windblown dust emissions for 2002.

Average 2002-04 98th percentile PM10-2.5 concentration valuesfor the IMPROVE Network sites.

PM10-2.5 98th percentile concentrations for sites withthree year mean values above 30 μg/m3.

Chiricahua NM Typical Visibility Day

Chiricahua NM Worst Visibility Day

Chiricahua NM Typical Visibility Day + 135 ug/m3 of PMcoarse

Chiricahua NM Typical Visibility Day + 100 ug/m3 of PMcoarse

Chiricahua NM Typical Visibility Day + 70 ug/m3 of PMcoarse

Chiricahua NM Typical Visibility Day + 50 ug/m3 of PMcoarse

PM10-2.5 Monitoring

• Only required in MSAs > 100,000 people– 0-5 sites per MSA– 225-250 sites across 150 MSAs– Emphasis on continuous mass conc. monitors

• Additionally …– Non-required PM10-2.5 concentration sites to

assess urban/rural differences– 50-100 speciation monitors at urban/rural sites

PM10-2.5 Monitoring

• Draft WRAP technical comments– Too little emphasis on non-urban areas– Too little emphasis on speciation– EPA should endorse use of IMPROVE

PM10-2.5 monitoring and support speciation of IMPROVE PM10-2.5 samples