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Technology Transfer Network / NAAQS
Ozone Implementation

Use of Special Purpose Monitoring Data

Information provided for informational purposes onlyNote: EPA no longer updates this information, but it may be useful as a reference or resource.

                    August 22, 1997

SUBJECT:  Agency Policy on the Use of Special Purpose Monitoring Data

FROM:     John S. Seitz, Director
          Office of Air Quality Planning and Standards (MD-10)

TO:       Director, Office of Environmental Measurement and Evaluation, Region I
          Director, Division of Environmental Planning and Protection, Region II
          Director, Environmental Assessment and Protection Division, Region III 
          Director, Air, Pesticides, and Toxics Management Division, Region IV
          Director, Air and Radiation Division, Region V
          Director, Multimedia Planning and Permitting Division, Region VI
          Director, Environmental Services Division, RegionVII
          Director, Air Program, Region VIII
          Director, Air Division, Region IX
          Director, Office of Air Quality, Region X

The Office of Air Quality Planning and Standards has received several inquiries from Regional Offices into how special purpose monitoring data can be used in making a variety of regulatory decisions such as designations, classifications, and attainment date extensions. We also have a final ruling from the U.S. Court of Appeals for the Third Circuit which supports the U.S. EPA denial of Pennsylvania's redesignation request for the Pittsburgh-Beaver Valley ozone nonattainment area. In light of these questions, legal developments, and the new National Ambient Air Quality Standard (NAAQS) implementation directives, I believe it is necessary to discuss the use of all publicly available special purpose monitoring data for all regulatory applications. The Agency policy on the use of all special purpose monitoring data for any regulatory purpose, with the exception of fine particulate matter data (PM-2.5), is that all quality-assured and valid data meeting 40 CFR 58 requirements must be considered within the regulatory process. This policy applies to all ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, lead, and particulate matter (PM-10) special purpose monitors, whether the data are reported into the AIRS database or available through other means. The recently finalized 40 CFR 58 particulate matter rule (62 FR. 38763) provides specific direction on how fine particulate (PM-2.5) data collected by special purpose monitors will be considered in the regulatory process.

Special purpose monitoring is conducted on a frequent basis in the United States for a variety of reasons. Examples of why State and local agencies use special purpose monitoring as a tool to supplement their ambient air monitoring networks include the need to obtain information on where to locate permanent monitoring stations, to provide additional data in support of pollutant formation and transport analyses, or to assess air quality in a particular location. Industries often operate special purpose monitoring sites in support of the Prevention of Significant Deterioration Program, and to satisfy their own information needs on air quality around their facilities. These studies vary in duration from being temporary sites needed only during a portion of the year to long-term air pollution studies over a large area. The U.S. EPA and other Federal agencies designate sites that are part of long-term studies or permanent networks as special purpose monitors, e.g., Clean Air Status and Trends Network (CASTNet) and National Park Service sites. Where public funds are expended to support these studies (.105 Grant funding for example), the responsible monitoring agency will generally report these data to the U.S. EPA as part of their routine monitoring data submittal into the Aerometric Information Retrieval System (AIRS), or in some other form, such as hard copy.

The U.S. EPA also recognizes that there are a number of special purpose monitoring stations operated and maintained by private entities using private funds that do not regularly report the data to the AIRS or to the Agency through other means. On occasion, select private entities will provide these data to the U.S. EPA on a voluntary basis. These types of special purpose monitoring sites are frequently operated as part of private research studies or as part of an industry group's interest in obtaining information on their local air quality.

Nationwide, we currently receive data from 5,209 criteria pollutant ambient air monitoring stations, of which 1,639 are special purpose monitoring stations operated by Federal agencies, State or local agencies, industrial groups, Tribal governments, or other private entities. While many of these 1,639 special purpose monitoring stations are operating in counties where other State and Local Air Monitoring Stations (SLAMS) are also actively reporting data, many of these special purpose monitors are operating in counties that do not have active SLAMS to provide supplemental information. As an example, there are 1,014 ozone monitoring stations reporting data to the AIRS, of which 151 are special purpose monitoring stations that are operating in counties that do not have other SLAMS supplementing the county's database. It is this subset of special purpose monitors, along with those special purpose monitors whose data are not reported to AIRS, that are expected to be affected by the U.S. EPA's policies regarding the use of special purpose monitoring data.

The Third Circuit Court decision supports the view that the EPA may not redesignate an area from nonattainment to attainment if the EPA knows that the area is not meeting the ozone NAAQS. Specifically, if the U.S. EPA knows of a violation or violations of the ozone NAAQS by either examining information within the AIRS or data from other sources and these data meet all 40 CFR Part 58 requirements, the U.S. EPA cannot determine that an area is attaining the NAAQS.

Existing 40 CFR Part 58 regulations do provide restrictions on the special purpose monitoring data used for demonstrations of attainment or nonattainment or in computing a design value for control purposes. Specifically, these data and monitoring sites must meet the requirements for SLAMS described in ..58.13, 58.22, and Part 58 Appendices A and E. These regulations are primarily concerned with the quality of the analyzer or sampling method and with the quality of the data reported. These restrictions do not include the requirement that the special purpose monitoring data be reported to the U.S. EPA's AIRS. The regulations also allow for alternative monitoring seasons (e.g., different ozone seasons) for special purpose monitoring sites provided that these alternative seasons are approved by the Regional Administrator. Briefly, the Part 58 requirements can be summarized as below:

1. The special purpose monitoring data must be from a U.S. EPA approved reference or equivalent method (.58.22).

2. The special purpose monitor must be operated in accordance with all applicable SLAMS quality assurance requirements as listed in 40 CFR Part 58 Appendix A.

3. The special purpose monitor must meet all probe or path siting requirements as defined in 40 CFR Part 58 Appendix E.

The U.S. EPA recognizes that decisions on the use or non-use of special purpose monitoring data may impact certain areas' designations and future regulatory actions. It is not U.S. EPA's intent to discourage additional special monitoring studies or to discourage the use of non-SLAMS data; however, under current regulations, U.S. EPA is obligated to consider all publicly available, valid (i.e., collected in accordance with 40 CFR 58), and relevant data in the NAAQS regulatory process. In addition to data reported to the AIRS, publicly available data may include data available from other sources including those special purpose monitors operated by third parties. Once the U.S. EPA is aware of these data from non-AIRS sources, the U.S. EPA should use reasonable means to obtain these data; verify that these data were collected in accordance with 40 CFR 58; and, once quality-assured, consider these data within the regulatory decision-making process. This policy clarifies previous agency policy interpretations. In particular, this revises two previous interpretations that only ozone data reported into AIRS would be considered when evaluating an area's compliance with the NAAQS. One interpretation was documented in the Federal Register for the correction to the classification of the Beaumont/Port Arthur Ozone nonattainment area (61 FR 14496) after going through a State implementation plan consistency analysis, and the second was documented in the Federal Register for the redesignation of the Bay Area from nonattainment to attainment with the ozone NAAQS (60 FR 27028).

Under the 8-hour ozone NAAQS, the OAQPS does not expect to use data from ozone monitors that operate for fewer than 3 years in judging compliance with the ozone NAAQS. This policy, which is consistent with the new 40 CFR Part 58 regulations for the measurement of fine particulate matter, should provide some relief to those agencies who operate short-term special purpose monitoring studies (no more than 2 years in duration). Specifically, this provision is expected to promote short-term ozone special monitoring studies in rural or remote areas where routine regulatory monitoring to assess population exposure is not normally conducted, and where implementing traditional local control measures would not provide for attainment of the ozone NAAQS. The U.S. EPA will propose regulatory revisions to 40 CFR 58 in April 1998 that will strengthen the Regional Office's flexibility in dealing with special purpose ozone monitors and using these data as appropriate.

The U.S. EPA also recognizes that this decision on the use of special purpose monitoring data may impact actions within the Federal Advisory Committee Act Subcommittee on Ozone, Particulate Matter, and Regional Haze Implementation based on recommendations from the Monitoring Incentives Ad Hoc Group. This group of external stakeholders has investigated ways in which the U.S. EPA can act to encourage additional monitoring and reduce regulatory burdens on affected entities. Among their many options, this group has recommended the formation of public-private partnerships to expand ambient monitoring, with a recommendation that all data be made publicly available. It is important to note that once these data become part of the public record, the U.S. EPA is obligated to use these data within the NAAQS regulatory process.

If you require further information, please contact Lee Ann Byrd at 919-541-5367 for information on 40 CFR Part 58 and monitoring; Tom Helms at 919-541-5527 for information on ozone and nitrogen dioxide air quality policy issues; and Joe Paisie at 919-541-5556 for particulate matter, carbon monoxide, lead, or sulfur dioxide air quality policy issues.


cc:  Deputy Director, Office of Ecosystem Protection, Region I
     Director, Division of Environmental Science and Assessment, Region II
     Director, Air, Radiation and Toxics Division, Region III
     Director, Science & Ecosystems Support Division, Region IV
     Director, Air RCRA, and Toxics Division, Region VII
     Director, Office of Environmental Assessment, Region X
     Lydia Wegman, OAQPS
     Henry Thomas, OAQPS
     William F. Hunt, EMAD
     Sally Shaver, AQSSD
     Tom Helms, AQSSD
     Joe Paisie, AQSSD
     Richard Scheffe, EMAD
     David Guinnup, EMAD
     Richard Ossias, OGC
     Lee Ann Byrd, EMAD
     Regional Monitoring Contacts
     Warren Freas, EMAD
     David Cole, AQSSD
     John Silvasi, AQSSD
     Barry Gilbert, AQSSD
     Larry Wallace, AQSSD

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