BOARD MEETING DATE: March 3, 2006
AGENDA NO. 31
PROPOSAL:

Proposed Ambient Air Quality Standard for Particulate Matter

SYNPOSIS:

U.S. EPA has proposed revisions to the Ambient Air Quality Standard for Particulate Matter. This item will summarize the proposed revisions and staff’s proposed comments.

COMMITTEE:

Mobile Source, February 24, 2006, Discussed

RECOMMENDED ACTIONS:

Receive and file.

Barry R. Wallerstein, D.Env.
Executive Officer

Background

Under the Clean Air Act, U.S. EPA is required to promulgate National Ambient Air Quality Standards (NAAQS) for certain air pollutants. These are commonly referred to as Criteria Pollutants, and include standards for particulate matter (PM). The Clean Air Act also calls for a review and, if appropriate, revision of the standards to reflect new information at five-year intervals. As a result of a consent decree resulting from a lawsuit brought by environmental organizations, U.S. EPA is scheduled to make a decision on any revisions to the particulate matter standards by September 27, 2006.

The Clean Air Act also calls for a review of the scientific information by the U.S. EPA’s Clean Air Scientific Advisory Committee (CASAC).

U.S. EPA has proposed revisions to the particulate matter standards as published on January 27, 2006 in the Federal Register, and is soliciting comments on the proposed revisions. Comments are due to U.S. EPA by April 17, 2006.

This letter summarizes the U.S. EPA proposal and staff’s recommended comments to the proposal. A draft comment letter to U.S. EPA is attached.

Staff has a number of concerns with the proposed revisions. These include: (1) the proposal for the new standards does not follow the recommendations of U.S. EPA staff or that of CASAC; (2) the proposal establishes for the first time a NAAQS standard that treats urban and rural area differently; and (3) the proposal establishes monitor siting criteria that would not adequately provide information to assess health impacts in rural areas.

The current set of particulate matter standards is summarized in the table below. The California standards are also shown for comparison.

Current PM Standards

PM 10
 
Federal
 
State
 
Annual
 
50 µg/m3
 
20 µg/m3
 
24 hr
 
150 µg/m3
 
50 µg/m3
 
PM2.5
 
Annual
 
15 µg/m3
 
12 µg/m3
 
24 hr
 
65 µg/m3
 
None

U.S. EPA proposes revising the primary NAAQS for PM to provide protection of public health, and to make corresponding revisions in monitoring reference methods and data handling conventions for PM. These revisions include the following.

  • Revise the PM2.5 standards
  • Revoke the PM10 standards
  • Establish a new PM10-2.5 standard (24-hour average only)
  • Establish criteria for PM10-2.5 reference monitoring method

With regard to primary standards for fine particles (particles generally less than or equal to 2.5 micrometers (µm) in diameter, PM2.5), U.S. EPA proposes to revise the level of the 24-hour PM2.5 standard to 35 micrograms per cubic meter (µg/m3), and to retain the level of the annual PM2.5 standard at 15 µg/m3.

With regard to primary standards for particles generally less than or equal to 10 µm in diameter (PM10), U.S. EPA proposes to revise the 24-hour PM10 standard in part by establishing a new indicator for thoracic coarse particles (particles generally between 2.5 and 10 µm in diameter, PM10-2.5), qualified so as to include any ambient mix of PM10-2.5 that is dominated by re-suspended dust from high-density traffic on paved roads and PM generated by industrial sources and construction sources, and 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. The U.S. EPA proposes to set the new PM10-2.5 standard at a level of 70 µg/m3. U.S. EPA proposes to revoke, upon finalization of a primary 24-hour standard for PM10-2.5, the current 24-hour PM10 standard in all areas of the country except in areas where there is at least one monitor located in an urbanized area (as defined by the U.S. Bureau of the Census) with a minimum population of 100,000 that violates the current 24-hour PM10 standard based on the most recent three years of data. In addition, U.S. EPA proposes to revoke the current annual PM10 standard upon promulgation of this rule.

These revisions are summarized below.

   PM2.5

  • No change to annual average: 15 µg/m3
  • 24-hour average: 35 µg/m3

   PM10

  • Rescind annual standard
  • Retain 24-hour standard in areas violating the current standard with populations > 100,000 until designations are determined for PM10-2.5

   Inhalable Coarse PM10-2.5

  • No annual standard
  • 24-Hour average: 70 µg/m3
  • Excludes areas impacted by wind blown dust, agriculture and mining determined from monitoring criteria

Staff Comments

Attached are draft staff comments of the proposed standards and monitoring criteria. The comments on the level of the standards are outlined below.

  • Support PM2.5 standards at low end of proposed ranges to protect public health
    • 24-hour average: 30 µg /m3
    • Annual average: 12 µg /m3
  • Support PM10-2.5 standard, without exception for specific sources or population size, at low end of proposed range
    • 24-hour average: 50 µg /m3
  • Support continuation of annual and 24-hour PM10 standards until the next SIP is approved to ensure continued progress toward clean air
  • Support further research on levels and components of PM related to health effects

Based on feedback received at the Board meeting, staff will finalize and submit the attached comment letter prior to the April 17, 2006 close of comment period.

Attachment (DOC 79kb)
Comment Letter to the U.S. EPA

/ / /



This page updated: June 30, 2015
URL: ftp://lb1/hb/2006/March/060331a.html