Cumulative Impact Analysis in Air Quality Permitting

Learn about and participate in the MassDEP initiative to incorporate cumulative impact analysis into the agency's review of comprehensive plan applications for proposed projects in or near environmental justice populations.

Table of Contents


MassDEP promulgated cumulative impact analysis regulations on March 29, 2024.  The regulations apply to comprehensive plan applications submitted on or after July 1, 2024.

MassDEP held two identical webinars on the new regulations – see How You Can Participate below for details.

Additional Resources

CIA Guidance and Tools

MassDEP has developed cumulative impact analysis guidance and tools for use by permit applicants and EJ populations.  See descriptions and links below.

Guidance on Conducting Cumulative Impact Analysis – Provides guidance on how to conduct a CIA including public outreach, assessment of existing community conditions, and analysis of cumulative impacts.

Cumulative Impact Analysis Mapping Tool – Provides maps and data for EJ communities (block groups), regulated facilities, and sensitive receptors needed for the assessment of existing community conditions.  Helps applicants to gather this information in the areas surrounding their proposed project and present the data in their CIA report.  Guides for this map are available in:  Español | 中文 | 中文(繁體) | Kreyòl Ayisyen | ភាសាខ្មែរ | Português | Tiếng Việt

Indicator Data for Cumulative Impact Analysis – This file contains indicator data for all EJ block groups in the Commonwealth for use in the assessment of existing community conditions.  MassDEP plans to update the data periodically.  See Indicator Data Release Notes for sources of the data.

Massachusetts Air Toxics Risk Screening Tool (MATRiST v2.1.1 4/26/2024) and Instructions – MassDEP developed a spreadsheet tool that can be used to estimate cumulative air toxics risks from proposed projects.  Instructions for using the tool are included in the README tab.  A Technical Memorandum describes how the default dispersion factors in the spreadsheet were developed.  For MATRiST revision notes see the Updates tab.  

Inhalation Toxicity Values (v1.0) – This spreadsheet contains the inhalation health benchmark values (acute noncancer, chronic noncancer, and cancer), references, and supporting information contained in MATRiST.  If an applicant conducts a comprehensive air toxics emissions risk characterization for their CIA report they should use these values.

What You Need to Know

Chapter 8 of the Acts of 2021, An Act Creating a Next Generation Roadmap for Massachusetts Climate Policy directed the Department of Environmental Protection (MassDEP) to:

  • Evaluate and seek public comment on incorporating CIA into its review of applications for certain categories of air permits and approvals;
  • Propose regulations for accomplishing this; and
  • Complete these tasks within 18 months of the signed legislation's June 2021 effective date (or by late December 2022).
  • MassDEP issued draft regulations in December 2022 and final regulations on March 29, 2024.

The Act also gave the Massachusetts Environmental Policy Act (MEPA) Office six months (or by late December 2021) to develop new regulations that would require:

  • Submission of an environmental impact report (EIR) for any project that is likely to cause damage to the environment and is located near an environmental justice (EJ) population;
  • Assessment of potential existing unfair or inequitable burden and related public health consequences; and
  • Analysis of how the proposed project might result in a disproportionate adverse effect on the EJ population.
  • The MEPA Office issued regulations in December 2021 and further amendments in January 2023.   

See Additional Resources below to learn more about environmental justice populations in Massachusetts. 

Additional Resources

How You Can Participate

MassDEP’s cumulative impact analysis (CIA) regulations require a program review to be completed by the end of 2025 and stakeholders will be provided the opportunity to comment on all aspects of the CIA regulations in that process.  If you are interested in staying informed of future stakeholder meetings please sign-up for cumulative impact analysis updates.

MassDEP held two identical webinars on the new regulations. The webinars provided an overview of the new regulations and associated guidance and tools, including CIA Mapping and Risk Screening Tools. These webinars were recorded and are available on MassDEP's YouTube channel.

Tuesday, April 30, 2024 at 9:00 am – 11:00 am
Webinar recording:
Cumulative Impact Analysis (CIA) Webinar on April 30, 2024 at 9:00 am

Thursday, May 2, 2024 at 6:00 pm - 8:00 pm
Webinar recording:
Cumulative Impact Analysis (CIA) Webinar on May 2, 2024 at 6:00 pm

Additional Resources

How to Stay Informed

Join the MassDEP email list to receive periodic updates on:

  • The cumulative impact analysis (CIA) regulatory development process;
  • Future stakeholder meetings; and
  • Opportunities for providing input to the agency.

Sign up by following the link in Additional Resources below.

Additional Resources

Contact   for Cumulative Impact Analysis in Air Quality Permitting

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