FACT SHEET REVISION OF METHOD 23 FOR THE DETERMINATION OF POLYCHLORINATED DIBENZO-P- DIOXINS AND POLYCHLORINATED DIBENZOFRURANS FROM STATIONARY SOURCES ACTION • On March 7, 2023, the U.S. Environmental Protection Agency (EPA) finalized EPA Method 23. Method 23 is used to measure polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from stationary air sources. • EPA promulgated Method 23 on February 13, 1991 (56 FR 5758). It has not been updated or revised since its original promulgation. Most current stationary source sampling and analysis methods have been revised to a new consistent format. This action revises the format of the method to be consistent with other methods. • These revisions harmonize the laboratory procedures and requirements with EPA Office of Water methods. This proposed revision replaces many prescriptive requirements for materials and instrument parameters with performance-based quality requirements that provide flexibility to implement best analytical practices. • EPA is has added polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) to the applicable target compounds in the method. This would provide EPA with a semivolatile compliance method for these regulated target compounds in one comprehensive method. • The revisions will improve the accuracy of Method 23 and will provide flexibility to stack testers and analytical laboratories who measure these semivolatile organic compounds from stationary sources while ensuring that the stack testing community can consistently implement the method across emissions sources and facilities. • This action will give facilities, source test teams and their analytical laboratories options to reduce field sampling cost when multiple semivolatile toxic compounds are required to demonstrate air release compliance. BACKGROUND • EPA established requirements for measuring PCDD/PCDF in stationary sources in 1991. Over the past nearly 30 years, technical advances for measuring PCDD/PCDF have occurred. • Most EPA stationary source compliance methods were reformatted in the 1990's. Method 23 is overdue for a format revision to the current Emissions Monitoring and Management Council standard. ------- FOR MORE INFORMATON • Interested parties can download the rule from the EPA Emissions Measurement Center website at the following address: https://www.epa.gov/emc/emc-promulgated-test- methods. • Other places to read the rule and background information (use Docket ID No. EPA-HQ-OAR- EPA-HQ-OAR-2016-0677): • EPA's electronic public docket and comment system at http://www.regulations.gov. • The EPA Docket Center's Public Reading Room (for hard copies). o The Public Reading Room is located at EPA Headquarters, Room Number 3334 in EPA West Building, 1301 Constitution Avenue, NW, Washington, DC. o Hours of operation are 8:30 a.m. to 4:30 p.m. eastern standard time, Monday through Friday, excluding federal holidays, o You will have to show photo identification, pass through a metal detector, and sign the EPA visitor log. Any materials you bring with you will be processed through an X- ray machine as well. You will be provided a badge that must be visible at all times. • For further information about the rulemaking, contact either Raymond Merrill at (919) 541-5225, Merrill.Raymond@epa.gov or Ned Shappley at (919) 541- 7903, Shappley.Ned@epa.gov. ------- |