Update on Upcoming Proposed Revisions to the PM 2.5 and PM 10-2.5 Standards

1. Update on Upcoming Proposed Revisions to the PM2.5 and PM10-2.5 Standards Colleen McKaughan, EPA Region 9 December 14, 2005

2. Overview • History and schedule for PM standards • PM2.5 -- current std. and EPA recommendations • PM10 -- current std. and EPA recommendations for a new PM coarse std. • Stakeholder comments • Status of Region 9 areas under the PM10 standards • Next Steps

3. History • The Clean Air Act requires periodic reviews and updates of air quality standards • A 1997 Court decision found PM10 to be a poorly matched indicator for PM10-2.5 particles because it includes PM2.5 • OAQPS has prepared a Staff Paper with recommendations for new PM fine and PM coarse standards to EPA’s Administrator

4. Schedule for the new standards • July 2005 - EPA’s Staff Paper was finalized • Sept 15, 2005 - Clean Air Scientific Advisory Committee (CASAC) provided a final letter to EPA with recommendations • The above two documents are available at www.epa.gov/ttn/naaqs/standards/pm/s_pm_index.html • Dec. 20, 2005 - consent decree deadline for proposed rule • Sept. 27, 2006 - consent decree deadline for final rule

5. Current PM2.5 Standards • 24-hour standard of 65 ug/m3 • Annual standard of 15 ug/m3

6. EPA Staff Paper Recommendations for PM2.5 Standard • New scientific evidence warrants a more protective standard • Strengthen the 24-hour std. to 25 - 30 ug/m3 and retain the annual std. OR • Strengthen the 24-hour std. to 30 - 40 ug/m3 and strengthen annual std. to 12 - 14 ug/m3

7. Current PM10 Standard • In the West, PM10 emissions are dominated by PM10-2.5 particles • 24-hour standard of 150 ug/m3 • Annual standard of 50 ug/m3 • Applies universally to all PM-10 and smaller-size particles • All monitored exceedences factor into the standard except those flagged and concurred as natural or exceptional events under EPA’s Natural Events Policy

8. Summary of EPA Staff Paper Recommendations for PM10-2.5 • Scientific evidence less certain than for PM2.5 • An urban (UPM10-2.5) 24-hour standard • No annual standard • UPM10-2.5 monitors to be located in areas with populations of 100,000 or more • Densely populated communities w/ 500 people/sq. mile are preferred for UPM10-2.5 monitoring locations

9. Summary of Staff Paper Recommendations for PM10-2.5 • 98th percentile standard ranging from 50-70 ug/m3 OR • 99th percentile standard ranging from 60-85 ug/m3

10. Summary of Staff Paper Recommendations for PM10-2.5 • Urban emphasis based on the following: • Toxicity is responsible for adverse health effects from coarse particles rather than size alone • PM coarse particles associated with heavily trafficked paved roads and industrial point sources are enriched by toxic contaminants • Higher exposures to coarse particles enriched by toxic contaminants generally occur in urban areas

11. Stakeholder Input • EPA held a public teleconference call with CASAC on August 11, 2005 • Several Region 9 States & Districts have provided adverse comments to EPA regarding exclusion of rural areas • CARB, ADEQ, NDEP • Great Basin APCD, Clark County DAQEM, Pinal County AQCD, Washoe County AQMD

12. Areas in CA, NV, and AZ Violating the PM10 Standards(based on ’02-’04 data) • 19 areas violating, excluding areas with exceedences likely caused by natural or exceptional events • With respect to the recommended UPM10-2.5 standard: • 6 areas have population < 100,000 • Another 5 areas have exceedences that would not be captured under a 98th percentile form of the PM coarse standard • Some of the remaining areas have one or more rural-setting monitors violating the standard

13. Next Steps • EPA’s proposed rule is due December 20 • www.epa.gov/ttn/naaqs/standards/pm/s_pm_ index.html • WRAP agencies will have an opportunity to provide written comments during the public comment period • We encourage collection of speciation data at both urban and rural PM monitors and research on rural dust toxicity