4 The record articles

Changes to the New Hampshire Air Toxics Rule: What Could It Mean for You?

Posted: May 3rd, 2021

Authors: John H.  David R. 
Hinkley and DR


The New Hampshire Department of Environmental Services (NHDES) is proposing revisions to Chapter Env-A 1400 (Regulated Toxic Air Pollutants) of the New Hampshire Code of Administrative Rules (Env-A 1400).  According to Env-A 1400, facilities using substances containing Regulated Toxic Air Pollutants (RTAP) must demonstrate compliance with Env-A 1400.  This means Env-A 1400 could apply to your facility even if it is not regulated by an air emissions permit from NHDES.

Env-A 1400 is most commonly applicable to manufacturing facilities which use products within their manufacturing process that contain RTAP.  Other examples include facilities burning a non-exempt fuel (e.g., landfill gas, resinated wood products) for heat and/or power, or facilities producing a renewable fuel (e.g., dried wood chips or wood pellets).

NHDES proposed changes to Env-a 1400 on August 8, 2020 and conducted an informational webinar on September 8, 2020 to present those changes to the public.  A public hearing is tentatively scheduled for May 2021 after formal rulemaking has been initiated.  The updated rule is expected to be finalized in Summer 2021.  More information about the rule can be found here: https://www.des.nh.gov/air.


The intent of the changes is to clarify aspects of the rule to make it easier to understand.  As a result, many sections have been reorganized and renumbered, with some new terminology defined and some existing terminology redefined or clarified.  A few noteworthy changes are as follows:

  • 18 RTAP compounds were added, 20 RTAP compounds were removed.
  • Aspects of 140 RTAP compounds were modified (e.g., compound description, de minimis threshold, ambient air limit (AAL), toxicity class). One notable RTAP change is proposed increases to the de minimis and AAL for formaldehyde, which were initially lowered, but then increased based upon information introduced through public comment.
  • Respirable particulate matter (PM) was defined as PM having an aerodynamic diameter of less than or equal to 100 micrometers (µm).
  • The definition of the compliance boundary (what is used for evaluating compliance with an AAL using air quality dispersion modeling) was changed to clarify where compliance must be demonstrated with air quality dispersion modeling. In particular, the revised rule clarifies the compliance boundary for leased properties and includes a provision for proposing an alternate compliance boundary other than the boundary in which an emissions source is located.
  • 90 days is the standard timeframe for demonstrating compliance after changes to a facility or the rule are implemented. If compliance cannot be achieved within the standard 90-day timeframe, there is a provision for a submitting a compliance plan for bringing a facility into compliance within three years.


There is no better time than the present to start planning!  Here are a few things you can do:

  • Determine if Env-A 1400 applies to your facility. If your facility is not exempt, start the process of evaluating how you will demonstrate compliance.
  • If Env-A 1400 applies to your facility, review the proposed changes and determine what must be done to comply with the rule, which could include expanding your RTAP emissions inventory, initiating a product substitution, installing an emissions control device, requesting an alternative compliance boundary, and performing air quality dispersion modeling.
  • Determine if Env-A 1400 will require an air emissions permit. Remember, compliance must be evaluated and demonstrated (e.g., with supporting documentation kept on-site) even if an air emissions permit is not required.
  • Set a compliance target date. According to Env-A 1406.02, compliance with the rule must be demonstrated 90 days of the rule change being finalized.  Note there are provisions in the proposed rule allowing facilities to propose a compliance plan describing how compliance will be achieved within three years of the date of the rule change.

If you have questions about Env-A 1400 changes, please don’t hesitate to reach out to David Ross at dross@all4inc.com (610-933-5246, x103) and jhinckley@all4inc.com (802-359-7295).


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