New Jersey Proposes Changes to Air Quality Modeling and Risk Assessment Procedures

April 2, 2018
Carol F. McCabe
MGKF News Flash

Risk assessment requirements and procedures are currently in focus in New Jersey.  The New Jersey Department of Environmental Protection (“NJDEP”) has taken a series of recent actions that will update, clarify, and potentially increase the scope of air quality evaluations that must be conducted by permitted facilities. 

In its Resiliency, Air Toxics and Exemptions (“RATE”) rulemaking finalized in January, NJDEP revised the reporting thresholds for hazardous air pollutants (“HAPs”) subject to air permitting.  While the reporting thresholds were loosened for a handful of HAPs, they were lowered for most HAPs, in some cases by a significant amount.  By way of example, the reporting threshold for formaldehyde was lowered from 400 lbs/yr to 3.5 lbs/yr, and the threshold for vinyl chloride was lowered from 40 lbs/yr to 5 lbs/yr.  The revised thresholds will determine which HAPs must be identified in air permit applications and will apply to toxics required to be included in annual emission statements.  While the RATE rule contemplates that most existing sources will address the revised reporting thresholds at their next permit renewal, the thresholds will apply immediately in the permit application process for new or modified sources.  A recent memo to NJDEP air permitting staff provides more detail with respect to how reporting thresholds for HAPs and non-HAP emissions will be applied in air permits.  Perhaps even more significantly, the more stringent reporting thresholds will determine whether the potential impacts of HAP emissions must be evaluated via New Jersey’s risk assessment procedures in the context of an air permit application.  Pursuant to its general authorities under Subchapters 8 and 22 to require the evaluation of ambient impacts of air emissions from permitted facilities, NJDEP has indicated that sources emitting HAPs in excess of the reporting thresholds will be subject to risk assessment procedures.

In addition to changed reporting thresholds, NJDEP has taken several recent actions to revise its risk assessment procedures.  First, late in 2017, NJDEP announced revisions to its Risk Screening Worksheet.  These changes included revisions to unit risk factors (URFs) used to evaluate carcinogenic risks and long-term and short-term reference concentrations (RfCs) used to evaluate non-carcinogenic risks.  In many cases, the values were made more stringent to comport with updated EPA and California risk factors; ethylene oxide is one example of a significantly more stringent URF under the revised worksheet.  NJDEP added sulfuryl fluoride to the Worksheet with an RfC developed under the California Pesticide Regulation.  NJDEP has indicated that n-propyl bromide is also being considered for inclusion in the Worksheet, based on EPA’s determination that n-propyl bromide may be reasonably anticipated to cause adverse health effects.  NJDEP inclusion of sulfuryl fluoride and n-propyl bromide in the Risk Screening Worksheet signals NJDEP’s intent to subject these pollutants to risk assessment procedures even though they are not considered HAPs and are not subject to reporting thresholds listed in the New Jersey regulations.  Other examples of non-HAPs included on the Risk Screening Worksheet include ammonia and hydrogen sulfide.   

More recently, NJDEP announced in March its proposed revisions to Technical Manual 1002 Guidance on Preparing an Air Quality Modeling Protocol and Technical Manual 1003 Guidance on Preparing a Risk Assessment for Air Contaminant Emissions.  The proposed changes to Technical Manual 1002 incorporate updates to National Ambient Air Quality Standards, federal modeling guidelines set for in 40 C.F.R. Part 51, Appendix W, and Prevention of Significant Deterioration (“PSD”) procedures updates, along with updated land use and meteorological data, among other changes.  Both Technical Manuals 1002 and 1003 address updates to NJDEP’s risk assessment procedures with more explicit incorporation of the air toxics, URFs and RfCs identified in NJDEP’s Risk Screening Worksheet, and detailed procedures for risk screening, refined risk assessment and facility-wide risk assessment procedures. NJDEP has also developed a risk assessment flow chart to assist in identifying the circumstances under which risk assessment may be required for Title V facilities.  

Taken together, the RATE rule’s tightened reporting thresholds and changes to risk assessment procedures in the Technical Manuals and Risk Screening Worksheet may be significant for Title V and other facilities emitting HAPs or other contaminants identified on NJDEP’s Risk Screening Worksheet.  A careful review of NJDEP’s actions, including the revised Technical Manuals, will be essential in determining how these changes may affect existing and new facilities.  NJDEP will accept comment on the revised Technical Manuals through April 18, 2018. 

For more information, please contact Carol McCabe at or 484-430-2304.