### 38762 Federal Register / Vol. 62, No. 138 / Friday, July 18, 1997 / Rules and Regulations

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 50

[AD–FRL–5725–4]

National Ambient Air Quality Standards for Particulate Matter

AGENCY : Environmental Protection Agency (EPA).

ACTION : Final rule; availability of supplemental information and request for comments.

SUMMARY : EPA is announcing the availability of certain laboratory and field test data, and related reports associated with the development of the reference method (Appendix L of 40 CFR part 50) for measuring PM 2.5 in the ambient air. Because these data were collected, by necessity, during and after the close of the public comment period on the proposed revisions to the national ambient air quality standards for particulate matter and thus, were not available for placement in Docket No. A–95–54 until late in the rulemaking process, EPA is announcing a supplemental comment period for the limited purpose of taking comments on these field and laboratory test results only.

DATES : Written comments must be received on or before August 18, 1997.

ADDRESSES : Submit written comments (duplicate copies preferred) to: Office of Air and Radiation Docket and Information Center (6102), Attn: Docket No. A–95–54, Environmental Protection Agency, 401 M St., SW., Washington, DC 20460.

FOR FURTHER INFORMATION CONTACT : John H. Haines, MD–15, Air Quality Strategies and Standards Division, Office of Air Quality Planning and Standards, Environmental Protection Agency, Research Triangle Park, NC27711, telephone: (919) 541–5533, email: haines.john@epamail.epa.gov or Neil H. Frank, MD–14, Emissions, Monitoring and Analysis Division, Office of Air Quality Planning and Standards, Environmental Protection Agency, Research Triangle Park, NC 27711, telephone: (919) 541–5560, email: frank.neil@epamail.epa.gov.

SUPPLEMENTARY INFORMATION : Elsewhere in today’s issue of the Federal Register

, EPA is publishing the final rule (FRL– 5725–2) revising the national ambient air quality standards for particulate matter. In Unit VI.B. (Appendix L—New Reference Method for PM 2.5 ) of the preamble to the final rule, EPA concluded that the proposed design and performance specifications for the reference sampler, with modifications described in the final rule, will achieve the design objectives set forth in the proposal. Accordingly, EPA has adopted the sampler and other method requirements specified in the revised Appendix L as the reference method for measuring PM2.5 in the ambient air. As discussed in the preamble to the final rule, a series of field tests were performed using prototype samplers manufactured in accordance with the proposed design and performance specifications. The results of these field tests confirmed that the prototype samplers perform in accordance with design expectations. Operational experience gained through these field tests did, however, identify the need for minor modifications as discussed in the preamble to the final rule. As explained in that preamble, EPA made other modifications to the proposed design and performance specification in response to public comment. As part of this process, EPA performed laboratory tests to ensure that the modifications achieved the intended objective. While the results of the field and laboratory tests were largely confirmatory in nature and did not indicate a need to alter the basic design and performance specifications, they did identify areas that needed further refinement. Given that these tests were performed, by necessity, during and after the close of the public comment period and because the results were not available for placement in the docket until late in the rulemaking process, the preamble to the final rule announced that a supplemental comment period would be held for the limited purpose of taking comments on these field and laboratory tests results. The following documents present the results of the field and laboratory tests and associated analyses that EPA considered, as discussed in Unit VI.B. of the preamble to the final rule, in making minor modifications or other refinements to the proposed reference method for measuring PM 2.5 in the ambient air. The documents are:
1. Adaptation of the Low-Flowrate, PM 10 , Dichotomous Sampler Inlet to Fine Particle Collection

.

2. Filter Temperature Specification Report

.

3. Flow Rate Specification Report

. 4. Laboratory and Field Evaluation of FRM Sampler Report

.

5. Prototype PM 2.5 Federal Reference Method Field Studies Report

.

These documents have been entered into Docket No. A–95–54 and are available for inspection and copying at the Office of Air and Radiation Docket and Information Office at the address in ‘‘ADDRESSES’’ at the beginning of this document. Copies may also be obtained by contacting Neil H. Frank at the address in ‘‘FOR FURTHER INFORMATION CONTACT.’’ It is emphasized that this supplemental comment period is for the limited purpose of taking comment on the documents specified in this document only. Comments on the reference method for PM 2.5 that go beyond the scope of these specific documents will not be considered. Upon close of the supplemental comment period, EPA will consider the comments received and decide whether any further action is appropriate. List of Subjects in 40 CFR Part 50

Environmental protection, Air pollution control, Carbon monoxide, Lead, Nitrogen dioxide, Ozone, Particulate matter, Sulfur oxides.

( Authority: Secs. 108 and 109, Clean Air Act, as amended (42 U.S.C. 7408, 7409)).

Dated: July 16, 1997.
Carol M. Browner,
Administrator.

[FR Doc. 97–18578 Filed: 7–17–97; 8:45 am]

BILLING CODE 6560–50–F