Evaluation of Particle Size Analysis Methods for Quantifying PM2.5 Emissions from Forest Products Industry Sources (BN-25-05)

Obtaining reliable PM_2.5 emissions data is essential for forest products industry (FPI) manufacturing operations. These data are needed to meet both federal and state emission regulations and reporting requirements. Moreover, robust and representative PM_2.5 emission factors are needed to demonstrate compliance with the National Ambient Air Quality Standard (NAAQS) for PM_2.5 during permitting processes, such as the installation of new or modified equipment or production expansions. Facilities previously met these requirements using overly conservative approaches, such as assuming all emitted particulate was in the PM_2.5 size fraction. However, these overly conservative approaches may no longer be viable to comply with increasingly lower standards.

Primary particulate matter with an aerodynamic diameter ≤2.5 μm (primary PM_2.5 or PM_2.5) is composed of both filterable and condensable particulate matter emitted directly from stationary point sources. The combination of two test methods, US EPA Method 201A for filterable particulate matter and US EPA Method 202 for condensable particulate matter, is normally employed for determining PM_2.5 emissions. However, the use of US EPA Method 201A poses challenges for many FPI emission sources. Some FPI sources may have entrained moisture or variable flow rates – conditions identified as inappropriate for the use of US EPA Method 201A. Additionally, the use of Method 201A on low emitting sources can lead to overestimates of PM_2.5 emissions due to blank contamination and inability to distinguish the signal (source emission) from noise (blank and inherent method bias). The studies summarized in this Briefing Note demonstrate the viability of particle size analysis coupled with US EPA Method 5 for use as an alternative to EPA Method 201A.

Authored by: Rob Crawford, Principal Research Scientist

Keywords: PM_2.5, emissions, particle size analysis, filter, Method 5, Method 201A