Final April 19, 2005

White Paper #1: What Pollutants Should a Revised Natural Events Policy (NEP) Cover?

Date/Status: April 19, 2005 Final

Background: The existing Natural Events Policy (NEP) applies only to exceedances of the PM10 National Ambient Air Quality Standard (NAAQS) caused by high wind events, seismic and volcanic activities, and wildfire events. Since the existingNEP was developed, EPA has implemented the NAAQS for PMfine(PM2.5) and is currently reviewing the existing PM2.5 NAAQS and the need for a PMcoarse or other PM NAAQS.

Discussion: Recognizing that uncontrollable natural events can have a deleterious effect on air quality and attainment of the NAAQS, EPA issued the NEP on May 30, 1996. The NEP was developed as a way to flag data in an area that, but for the natural event, would be attaining the NAAQS. The NEP lays out the timetable and procedures by which States flag monitoring data that is collected during natural events, including high winds, seismic and volcanic activities, and wildfires.

In the past few years, several States have worked with EPA regional offices to flag data that was affected by natural events. Based on the experience gained through those efforts, several western states suggested that the NEP be modified to better facilitate meeting the intent of the NEP. However, revising the NEP was delayed based on the assumption that a revision would be required as a result of the implementation of new NAAQS for PM2.5 and possibly PMcoarse, and it was agreed that these issues would be addressed at that time.

Implementation of the PM2.5 NAAQS is well under way, although EPA is currently reviewing that standard, as well as the need for a PMcoarse NAAQS. Because the NEP does not specifically address PM2.5 or PMcoarse, EPA has used its legal creativity to extend the current policy to include PM2.5 and the policy has not been revised; however, if that creativity is successfully challenged, it is the States who will be responsible to develop the resulting State Implementation Plans.

Since the NEP was developed, EPA has also developed the PM10 Limited Maintenance Plan option and rules for implementation of the Regional Haze requirements of the Clean Air Act. These issues were not considered when the NEP was developed.

Recommendation:

The NEP should be revised to specifically include all forms of PM, including PM2.5 and PMcoarse.

Task Group Members:

Dave McNeill, Utah—author

Doug Schneider, Washington—reviewer

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