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
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