PM2.5 Continuous Monitor Comparability Assessment Tool - Technical Note

Sep 4, 2026

Uploaded by Angel

PM2.5 Continuous Monitor Comparability Assessment Tool provides one-page technical reports evaluating how a PM2.5 continuous monitor performs when collocated with an FRM sampler. Reports support monitoring agencies in judging whether continuous monitors in their network meet intended objectives, including comparisons to NAAQS and/or AQI reporting. Results are summarized by fixed seasons across years, by individual years, and for the full dataset. Interpretation focuses on AllData (A) or the last complete year, using benchmark tests and referenced assessment methods to compare FEM consistency across agencies.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages4

Reading Time10 min

AccessFree to download

Summary

Interpretation approach

Data and assessment framework

Dataset descriptors and seasonal definitions

Linear regression relationship (1:1 and regression)

Difference trend illustration

Part 53 specifications (slope, intercept, correlation, CCV)

Mean and bias calculations

Referenced methods and appendices

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY RESEARCH TRIANGLE PARK, NC 27711 OFFICE OF AIR QUALITY PLANNING AND STANDARDS Technical Note-PM2.5 Continuous Monitor Comparability Assessment1 The PM2.5 continuous monitor comparability assessment tool is available at: [https://www.epa.gov/outdoor-air-quality-data/pm25-continuous-monitor-comparability-assessments](https://www.epa.gov/outdoor-air-quality-data/pm25-continuous-monitor-comparability-assessments) Summary: This tool provides a one-page technical report that assesses the comparability of a PM2.5 continuous monitor when collocated with an FRM sampler. These reports are intended to assist monitoring agencies in understanding if the PM2.5 continuous monitors operated in their network are appropriate for their intended monitoring objective (i.e., comparison to the NAAQS and/or reporting the AQI). Data are summarized by season across years, by year, and for all data. The most appropriate way to interpret the comparability of the PM2.5 continuous monitors is to look at either the entire data set, designated as “AllData” or “A”, or view the last complete year of data. The comparability assessments are presented in the context of several benchmark tests to assist with that evaluation. The assessment methods are described in detail in the following memo-Assessment of PM2.5 FEMs Compared to Collocated FRMs available at: [https://www3.epa.gov/ttn/naaqs/standards/pm/data/HanleyandReff040711.pd](https://www3.epa.gov/ttn/naaqs/standards/pm/data/HanleyandReff040711.pdf. The)[f](https://www3.epa.gov/ttn/naaqs/standards/pm/data/HanleyandReff040711.pdf. The)[. The](https://www3.epa.gov/ttn/naaqs/standards/pm/data/HanleyandReff040711.pdf. The)[memo also provides a set of graphical outputs for comparing the most widely used FEMs to the one-page](memo also provides a set of graphical outputs for comparing the most widely used FEMs to the one-page)[ ](memo also provides a set of graphical outputs for comparing the most widely used FEMs to the one-page)assessments described in this technical note, allowing users to understand if their FEMs are consistent with FEMs operated in other agencies. Description of Data and Assessments: The following information describes the data and assessments in the one-page reports: Table 1 – Dataset Descriptors | Dataset | Short
Descriptor | Color of
descriptor or
data points | Description | | --- | --- | --- | --- | | AllData | A | black | Represents all the data in the assessment | | Winter | W | blue | Winter is represented by the dates December 21 – March 20. | | Spring | R | green | Spring is represented by the dates March 21 – June 20. | | Summer | S | red | Summer is represented by the dates June 21 – September 20. | | Fall | F | brown | Fall is represented by the dates September 21– December 20. | | Year | 0-9 | black | Full calendar year | Note: Seasons are fixed dates regardless of year. Illustration of Linear Regression Relationship: On the top left of the page a regression relationship is illustrated and the regression equation is presented along with the correlation of the equation. A 1:1 line is drawn as a solid line to quickly assess if data points are above, below, or straddling the 1:1 line. A dashed line is drawn as the regression relationship. The FRM is presented on the X-axis, while the continuous method is presented on the Y-axis. 1 In May 2018, the PM2 .5 continuous monitor comparability assessment was updated to account for multiple FRMs at the same site that are reported as separate POCs. The assessment uses the lowest available FRM POC available on a given day. The result of this change increases the available FRM samples to use in the assessment. Illustration of Difference Trend: On the top right of the page a trend is illustrated based on the difference between the continuous and FRM method. Data are presented in a color coded manner to determine any seasonal patterns, should they exist. Part

FAQs

What does the PM2.5 continuous monitor comparability assessment evaluate?

It assesses the comparability of a PM2.5 continuous monitor when collocated with an FRM sampler, supporting evaluation for intended monitoring objectives such as NAAQS comparison and/or AQI reporting.

How are results organized for interpretation?

Data are summarized across fixed seasons for multiple years, by year, and for all data. Interpretation is recommended using either the entire dataset (AllData/A) or the last complete year.

Which benchmark tests and outputs are used in the assessment?

The tool presents assessments in the context of benchmark tests, including linear regression comparisons, difference trend visuals, and Part 53-based criteria for slope/intercept and correlation relative to CCV, along with bias calculations using referenced equations.

Sep 4, 2026

Uploaded by Angel