Method 25A Bulletin
To:  All Regional, State and local Agencies
From:  Rima Dishakjian, Emission Measurement Center

     An issue has come up recently concerning the application of Method 25A
data as a surrogate for measuring individual Hazardous Air Pollutants (HAPs)
in upcoming MACT rules. Some source testers have called me and asked if they
could subtract out methane, ethane, etc. (exempt solvents under the VOC rules)
from the Method 25A values.  According to the reg writers at ESD, the answer
is NO.  If the data collected to support the regulation was raw Method
25A values, the regulation was based on data which included methane, ethane,
etc.  Since this is not a VOC rule, the exempt solvent subtraction rule
would not apply here.  Please read the applicable regulation carefully
when enforcing a MACT rule, and call me at (919) 541-0443 or the reg writer
to check on this.