In May 2011, the US EPA promulgated the new Method 202 for the collection of condensable particulate matter. At elevated stack temperatures some pollutants behave like gas, however, when these emissions are mixed with air at ambient temperatures, the pollutants “condense.” The resulting condensed particulate can cause respiratory problems, according to EPA studies. A primary factor for their impact on respiratory conditions is particle size. The condensed particles have a diameter less than or equal to 10 microns, with perhaps a great majority occurring at the sub 2.5 micron level.

New Method 202 vs. Old Method 202

The new Method 202, which employs dry impingers, demonstrates lower bias than the old Method 202, which employs wet impingers. Indiana is one of a few states in the United States that requires source compliance testing for condensable matter, specifically PM 10 (particles at 10 micron or less) and PM 2.5 (particles at 2.5 micron or less). Some of our clients have questioned whether the new Method 202 is biased lower than the old Method 202. Wilcox’s Air Analysis Division has performed side by side studies of old Method 202 vs. new Method 202. Performing the tests simultaneously with each other is important to make testing conditions equal. In those instances where testing has been conducted, the new Method 202 produced lower emissions vs. the old Method 202. However, different operations may produce different results.

Are You Up To Date With Your PM Testing?

What if a source test was performed prior to May 2011 using the old Method 202 and showed compliance to their PM 10 limit, then conducted a test after May 2011 using the new Method 202, in which non-compliance was shown? The regulatory agencies consider the new Method 202 as the compliance method. The old Method 202 is no longer valid. Any testing for PM 10 in which condensable particulate will be sampled must employ this new method. A source must recognize that while a previous test using the old Method 202 demonstrated compliance, the new Method 202 may not provide similar results. In particular, this may be the case because condensable particulates are not typically controlled by a baghouse. A source can perform an engineering stack test to assess its PM 10 emissions. It is important to determine the source of the condensable particulate, should the data indicate that adequate control may not be achieved under current operation conditions. Both organic and inorganic materials may result in condensable particulate. Once the material is known, an appropriate control can be designed.