Overview
On March 2, 2026, the Massachusetts Department of Environmental Protection (MassDEP) released a discussion document proposing revisions to its 1990 Noise Policy (the Policy). As currently implemented, the Policy guides the agency’s evaluations of compliance with the Commonwealth’s noise regulations under 310 CMR 7.10. MassDEP’s highly anticipated revisions to the Policy seek comments and guidance on: baseline sound levels, noise measurement points, compliance evaluation for existing permitted sound sources, tonal sound definitions, and a revised approach to conducting sound studies. According to MassDEP, these revisions seek to increase clarity in the application of the Policy, reflect advances in acoustical measurement practices, and address stakeholder concerns regarding how the Policy affects projects in areas with very low background sound levels.
Background
In Massachusetts, M.G.L. Chapter 111 and the Air Pollution Control Regulations at 310 CMR 7.00 regulate noise as a form of air pollution. The authorizing regulation, 310 CMR 7.10, is part of MassDEP’s air regulations and prohibits unnecessary or excessive noise from man-made sources, including industrial commercial facilities and construction equipment. The regulations define noise as “sound of sufficient intensity and/or duration as to cause or contribute to a condition of air pollution.”
MassDEP proposed revisions to the Policy in response to the Commission on Energy Infrastructure Siting and Permitting’s March 29, 2024 recommendations to Governor Healy, as well as requests, input, and comments from local health officials and the regulated community. The Commission’s recommendation suggested that MassDEP update the Policy to “address the disparity of treatment of projects proposed in rural versus urban area,” which is due to the lower ambient background noise typical of rural areas and the Policy’s focus on noise increases of more than 10 dBA above ambient, rather than setting a specific decibel threshold.
Municipal by-laws or ordinances regulating noise are not affected by the Policy, which serves as agency guidance for applying (during permitting) and enforcing 310 CMR 7.10. State law provides local authorities, such as boards of health, with broad authority to investigate and address nuisance conditions, including noise – a framework the revisions would not alter. MassDEP regulations also empower local authorities to bring enforcement action against anyone who violates applicable noise regulations.
Current Noise Policy Framework
As currently drafted and implemented, a sound source violates the Policy if it raises the sound level by 10 dBA above the ambient background level or creates a “pure tone condition” (a more technical measurement). Both criteria are measured at both the source’s property line and the nearest receptor (e.g., a residence). The Policy currently defines ambient as “the background A-weighted sound level that is exceeded 90% of the time measured during equipment operating hours” but permits alternative definitions as permitted by MassDEP; the Policy also describes how MassDEP measures ambient background noise, which generally occurs during the quietest period, when the relevant noise source is not operating, and which can result in very low ambient background noise levels of 20-30dBA in rural areas.
Proposed Policy Changes
MassDEP seeks comment on its proposed revisions to the Policy, which include:
- Establishing a presumption that sound levels of 40 dBA are acceptable for sensitive receptors and in what the discussion document refers to as “very quiet areas.” This change would partially replace the Policy’s “no more than 10 dBA above ambient” test, setting an effective floor at 40 dBA to address concerns about disparities between urban and rural areas.
- Clarifying that compliance evaluations generally should focus on measurement at sensitive receptors, such as residences, schools, hospitals, and elder care facilities, rather than measurement at the sound source’s property line.
- Utilizing the average of the lowest hourly L90 (measured ambient sound) levels in sound studies. MassDEP has previously required significant air pollution sources that emit sound to conduct sound studies. The sound studies used the lowest hourly L90 sound level from seven days of continuous monitoring, which often resulted in “very low” and unrepresentative background levels.
- For sound sources permitted by MassDEP, the Energy Facilities Siting Board, or a local authority, compliance should be evaluated primarily against any applicable noise requirements and conditions outlined in the permit or authorization. This potentially means MassDEP would defer to permit conditions, which could be more or less strict than the Policy or regulations.
MassDEP is also seeking comments on how to define tonal sounds, specifically the extent of to which the definition should align with generally accepted industry standards and what flexibility should exist in the definition. While the agency has not proposed any specific language at this time, implementing these changes to the Policy would alter how MassDEP assesses operational noise for a variety of industries and may have ramifications for developers of energy, solid waste, and other infrastructure.
Comment Deadline
MassDEP is accepting comments on the discussion document through 5:00 pm, March 23, 2026. Comments may be summited via email to Michael.Woodman@mass.gov or by mail to Michael Woodman, MassDEP, Bureau of Air and Waste, 100 Cambridge Street, Boston, MA 02114.
