The PM Challenge

• By: AWMA
• On: 02/05/2025 13:18:27
• In: EM Articles
• Comments: 0

by Eric L. Hiser

The regulatory evolution in PM permitting has created unique challenges for regulators, testers, modelers, and the regulated community. The complexity resulting from particulate matter including filterable, condensable and secondarily formed material makes PM a particularly interesting pollutant from a scientific and regulatory perspective.

In this month's first article, David Nash and Paul Van Rooy, both with EPA's Air Quality Assessment Division, provide an overview of current concerns with the measurement and understanding of condensable PM. The authors outline the evolution of current Method 202 and discuss improvements in replicability of the method when consistently performed. The authors then discuss Other Test Method 37 (OTM 37) and provide an overview of a series of analyses run using both Method 202 and OTM 37.

In the next article, Rich Trzupek, with Alliance Technical Group, echoes Nash and Van Rooy's call for further research in particulate measurement but with greater urgency. Trzupek notes that unlike other methods, which focus on unique aspects of a pollutant to measure it, PM methods utilize mass and so as the amount of allowable mass decreases, the accuracy and precision of gravimetric measurement declines.

In our third article, William B. Jones, with Blue Sky Modeling, reviews the challenges of modeling PM accurately. One of the first challenges, as outlined in the other articles, is obtaining accurate emission inventory data. The second challenge is that AERMOD, the workhorse model for most source-specific ambient modeling, does not directly calculate secondary PM.

The articles in this issue outline why PM is often a complex problem for sources. All of these factors make particulate matter a worthy subject for additional attention. We hope that you enjoy this issue's review of just some of the issues confronting regulators, scientists, advocates and the regulated community when they seek to address the complex challenge of PM.

Continue reading the full Feburary 2025 issue of EM.