EPA Method 201A - Particulate Emissions

Method Overview

  • Semi-Isokinetic sampling method (constant rate sampling procedure)
  • PM10 and PM2.5 size separation device (cyclone)
  • In-Stack filter.
  • "Condensible" particulates pass through the filter & cyclones and condense in impingers. Can readily be combined with a CPM Method.
  • This method is applicable for the determination of PM emissions where the concentrations are known to be independent of temperature over the normal range of temperatures characteristic of emissions from a specified source category. It is intended to be used only when specified by an applicable subpart of the standards, and only within the applicable temperature limits (if specified), or when otherwise approved by the administrator.
  • This method is not applicable to stacks that contain liquid droplets or are saturated with water vapor.
    • EPA Technical Information Document (TID) 009 suggests that EPA Method 5 be substituted on stacks where water droplets are known to exist in the emissions;
    • It further suggests that the EPA Method 5 (or a comparable method) results be considered as PM10 Emissions
  • Stainless steel nozzles should be used with great care, port scrapings can bias results high.

Target Compounds

  • Total Particulate Matter (PM) -- those substances retained in the sampling nozzle, within a cyclonic size separation device and on a filter. Particulate Matter with an aerodynamic diameter less than ten micrometers (PM10) and less than 2.5 micrometers (PM2.5) - those substances that pass through in-stack cyclonic size separation devices and are collected in the probe and on a filter.

Performance Tips

  • Constant sample rate used to maintain constant cyclonic separation device cut-points in cyclone separation devices.
  • Do not use silicone grease - it can be soluble in the probe rinse and can bias the PM value high.
  • Vary the dwell time (sampling time) at each sample point proportionately with the point gas velocity.
  • Remove the sizing devices (cyclone heads) prior to post-test leak check in order to minimize disturbance of the sample distribution prior to analysis.
  • Stack temperatures can not vary by more than 50oF from lowest to highest in order to keep constant sample flow rates. Sampling volume is a function of temperature.
  • Method 201A cannot be used to measure emissions from stacks that have entrained moisture droplets (e.g., a wet scrubber stack), since these stacks may have water droplets larger than the cut size for the PM10-sizing device. To measure PM10 in stacks where water droplets are known to exist:
    • EPA’s Technical Information Document ( TID-009:Methods 201 and 201A in Presence of Water Droplets) recommends use of Method 5 of Appendix A to 40 CFR part 60 (or a comparable method) and consideration of the particulate catch as PM10 emissions.


  • Acetone must be shipped as a hazardous material. Please call for IATA codes if you need them.
  • Samples may be shipped at ambient temperatures.
  • It may prove more economical to keep acetone rinses separate, ship other samples normally, and the acetone as hazardous.
  • Be sure to include a chain of custody for each shipping container.


  • This method is currently the EPA's Go-To method for PM10 and PM2.5 Emissions Measurement;
    • Other Particle Size Distribution Determination Methods can be Substituted.
    • In-Situ Measurements Using Impactors;
    • Laboratory Analysis of Filter Catches.
  • Can be combined with EPA Method 202 for Condensable Particulate Matter.


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