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Why Should Plants Care About EPA’s Recent Changes for CPM?


What do EPA’s proposed changes to Method 202 mean for someone who is hiring a contractor to perform stack emission sampling?

In late August of 2017, EPA proposed revisions to Method 202 for condensable particulate matter (CPM). EPA states that its goal with the proposed revisions is to improve consistency in the method and eliminate known biases.  You can see their summary page here.

These proposed changes will impact stationary source owners and operators that must use Method 202 to determine compliance with standards regulating particulate matter smaller than 2.5 microns (PM2.5), or any stationary source owner/operator that is required to measure CPM via this method for any reason.

What changes is EPA proposing to make?

There are numerous proposed changes to the method, but they typically fall into four categories.

  1. Eliminating Systemic Errors – These changes attempt to limit the biases that the method currently introduces to the measurement. Unfortunately for operators of these sources, many of the biases work against you.  Revisions here include modifications to the sample train, suggested limits to run times, and increases to the requirements for calibration recordkeeping.
  2. Limiting Optional Equipment or Procedures – To increase industry-wide consistency of the measurement, EPA is limiting some of the choices that testers have historically been allowed to make. This includes changes to the rules regarding field train blanks and field reagent blanks, and clarifications on the applicability of the method.
  3. Quantifying and Reducing Blank Contamination – The EPA is proposing modifications to glassware cleaning procedures, reagent blanks, and blank correction calculations. These changes are intended to more appropriately quantify the systemic bias in the method. These changes are important to plants since any residue in the sampling equipment in excess of a specified limit is considered to be CPM from your process.
  4. Adding Flexibility – Counter to the above categories, EPA is proposing to allow some options that the testing industry has shown to be advantageous. Stack testers will be allowed more options for sample containers and weighing containers under these proposed changes.

To see all the changes in detail, visit EPA’s website.

What will change when you bring a contractor onsite to conduct a Method 202 test?

From an operator’s perspective, not much will change.  The method will remain mostly unchanged and this is all part of an improvement process that dates back for many years.  Someone with a keen eye might notice a few things though including:

  1. A longer setup time.
  2. Vertical condensers in the sample train.
  3. Run times limited to 2 hours.

Also, the report will change slightly.  It will take someone with an even keener eye to notice:

  1. A report with more ancillary data regarding the train purge, balance calibrations, and other recordkeeping.
  2. Higher allowable blank reductions.
  3. Slightly lower CPM numbers due to elimination of biases.

What is the timeline for comments?

The comment period lasts for 60 days.  We are already more than halfway through that; the comment period ends in late October.  As for when the proposed rule changes will go into effect, that is unknown at this time.

Will my testing contractor be ready for all this?

It’s hard to say. CleanAir’s stack testing team, like many testing organizations, has already incorporated many of these changes into our procedures based on a 2016 guidance document issued by EPA.  Hopefully, most of the changes can be implemented without incurring much in the way of additional costs.

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