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What you Need to Know About Recently Finalized Updates to Philadelphia’s Air Toxics Regulations Effective January 1, 2024

Posted: July 13th, 2023

Authors: Luke Z. 

Philadelphia’s Air Management Services (AMS) recently posted edits to its May 2022 proposed revisions to Air Management Regulation (AMR) VI concerning the control of emissions of toxic air contaminants (TACs), sometimes referred to as air toxics. At a public meeting on April 27, 2023, the Air Pollution Control Board approved the proposed amendments to AMR VI as final and designated the effective date of the updated regulation as January 1, 2024. This will be the first major update to AMR VI since its original promulgation in 1981. The full report of this public meeting can be found on the Philadelphia AMS Notice Board.

As noted previously, the revised AMR VI largely resembles the New Jersey Department of Environmental Protection’s (NJDEP’s) air toxics program that includes toxic substances regulations and a risk assessment process, with some notable additions. The revised AMR VI regulation includes some additional air toxics not listed in the NJDEP requirements, such as diesel particulate matter, and will require inclusion of existing background levels of air toxics in the risk assessment. The process for determining the existing background air toxics concentration levels is presently not well defined.

The list of TACs in AMR VI has been expanded from the existing 99 to 217 pollutants, including nearly all 187 pollutants currently classified as hazardous air pollutants (HAPs) by the U.S. Environmental Protection Agency (U.S. EPA) pursuant to Section 112 of the Clean Air Act (CAA). The reporting threshold is the annual emissions rate level in pounds per year from a source that, when exceeded, would trigger the requirement to conduct a health risk analysis. A source with potential air toxics or HAP emissions below this reporting threshold would not require an air toxics risk assessment and would be considered an insignificant source (i.e., would not require a permit or certificate) assuming all other air permit exemption criteria were met.

This regulation has the potential to affect the regulated community broadly because all Title V facilities applying for any installation permit or plan approval for new or modified equipment that emit a TAC that exceeds its risk screening threshold (found in Table 1 of the Technical Guidelines for AMR VI) will now be required to conduct an initial health risk assessment using: AMS’s Risk Screening Workbook; U.S. EPA’s air quality screening model, AERSCREEN; or an alternative air screening model approved by AMS on a case-by-case basis. TACs that do not pass this initial health risk assessment (i.e., the TAC has a cancer risk > 1 in a million and/or has a non-cancer hazard quotient > 1) will need to go through a refined risk screening assessment using modeling software such as U.S. EPA’s AERMOD, which utilizes stack- and source-specific data and representative meteorological data. Risk at a level greater than or equal to 50 in a million constitutes an unacceptable risk, and AMS will not approve a permit application at this risk level.

Additionally, and likely the most significant change in AMR VI, is that Title V facilities will be required to conduct a facility-wide health risk assessment if the permittee is seeking an initial Title V permit or seeks to renew an existing Title V permit for a facility where air toxics will be emitted in excess of the reporting thresholds.

With an effective date of January 1, 2024, AMR VI will need to be addressed by facilities regulated by AMS that submit permit applications on or after that date. Air permit applications will invariably become significantly more complex for facilities to prepare and for AMS to approve.

ALL4 has been tracking the development and approval of this regulation closely. We have experts fluent in navigating New Jersey’s stringent air toxics requirements and will likewise be able to help your facility prepare for Philadelphia’s impending regulatory update. If you have questions about how these updates affect your Philadelphia facility, don’t hesitate to reach out to me at lzhu@all4inc.com or your regular ALL4 contact.


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