Air Monitoring and Reporting

The Maine Department of Environmental Protection operates and maintains a variety of ambient air monitoring equipment around the state. Some of these instruments operate on a continuous basis and provide hourly averages of pollutants or meteorological data that is used in the evaluation of the air pollutant data. Data may also be collected over a twenty-four hour period such as particulates or it may be collected as a composite over an entire week. Examples of the latter are the atmospheric and mercury deposition monitoring programs. The number of monitoring sites and the pollutants that are monitored may vary from year to year depending on the expected concentrations of the pollutants, the origin of the pollutants and new programs based on changes in existing regulations or the establishment of new regulations. For more information, contact Andy Johnson (207) 480-0906.

Air Monitoring Data including:

Chronic Ambient Air Guidelines (2023): Ambient Air Guidelines (AAGs) represent chemical concentrations in ambient air, below which there is minimal risk of a deleterious health effect resulting from long-term inhalation exposure. The AAGs are derived to be protective for effects due to chronic exposure (“chronic” refers to long-term exposure); therefore, these guidelines are most appropriately compared with long-term average ambient air measurements (e.g., annual averages).

Emissions Inventory

  • CAERS is a free web based reporting system developed by EPA to assist facilities with their annual air emissions reporting requirements. Log in to CAERS
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Monitoring Sites Map Legend

The Maine Department of Environmental Protection (ME DEP) operates a network of ambient air monitoring sites at locations across the state. ME DEP is required to submit an Annual Ambient Air Quality Monitoring Network Plan to the US Environmental Protection Agency (EPA). This document was subject to a 30-day public comment period with a draft posted on this web site before being submitted to EPA for review and approval. The 2024 final plan was submitted to EPA on July 1st, 2023, and final approval was received on August 7th, 2023. On September 25th, 2023, two mistakes on the 2024 Sample Schedule calendar on page 27 were corrected and the annual air monitoring plan was republished.

Annual Air Monitoring Plan 2023

Annual Air Monitoring Plan 2024

Five Year Assessment of Maine's Ambient Air Monitoring Network (pdf) - The Five Year Monitoring Network Assessment is required by EPA and allows all who are invested in Maine’s air quality to consider DEP’s air monitoring program objectives in the context of “the bigger picture,” and from a vantage point five years into the future.Originally presented to EPA on October 7, 2020, this revision from May 19, 2021 reflects modifications incorporated after receiving comments and suggestions Region 1 staff.