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MassDEP Ambient Air Quality Monitoring Network & Annual Plan

Learn about which pollutants and parameters the agency measures at specific monitoring sites, and why.

About the Monitoring Network & Plan

The Massachusetts Department of Environmental Protection (MassDEP) operates a network of 23 ambient air quality monitoring stations at locations across the state. The Wampanoag Tribe of Gay Head (Aquinnah) operates an ozone monitoring station on Martha's Vineyard. Each year, MassDEP is required to submit an Annual Ambient Air Quality Monitoring Network Plan to the U.S. Environmental Protection Agency (EPA). This document and its attachments are subject to a 30-day public comment period before MassDEP submits them to EPA for review and approval.

The annual network plan describes to EPA which pollutants and other parameters MassDEP measures at its various ambient air monitoring sites and why they are measured at those specific locations. It also describes changes in the network - including new and closed locations, and new and discontinued measurements at existing locations - since the last network plan, as well as proposed changes in the network over the next 18 months.

MassDEP also must conduct an assessment of the Massachusetts Ambient Air Quality Monitoring Network every five years to determine whether it meets the objectives defined in EPA regulations.

Air Monitoring Network Sites Map & Table

Zoom in ( + ) and click on the icons to learn about each monitoring station site across Massachusetts.

Legend of Parameter Acronyms

O3 Ozone
CO Carbon Monoxide
SO2 Sulfur Dioxide
NOx Nitric Oxide, including Nitrogen Dioxide
NOy Total Reactive Oxides of Nitrogen
MET Meteorological Parameters
PM10 Particulate Matter (10 microns & smaller)
PM2.5 Fine Particles (2.5 microns & smaller)
VOC Volatile Organic Compounds
TOXICS Toxic Air Pollutants including Carbonyls (Aldehydes), Metals & VOCs
BC Black Carbon
SPEC Speciated Fine Particles
IMPROVE Visibility PM Speciation

Final 2020 Network Plan & Five-Year Network Assessment

In addition to submitting an Ambient Air Monitoring Network Plan to the U.S. Environmental Protection Agency (EPA) for review and approval annually, MassDEP is also required to conduct a Network Assessment once every five years.

The assessment determines whether the state's network meets the monitoring objectives defined in 40 CFR part 58 Appendix D, whether sites need to be added or discontinued, and whether new technologies should be incorporated into the ambient air monitoring network.

MassDEP held a 30-day public comment period on its Draft 2020 Network Plan and 2020 Five-Year Network Assessment, accepting comments through September 10, 2020, and finalized these documents in December 2020.

See Additional Resources below for the final Network Plan and attachments, the final Five-Year Network Assessment, and MassDEP's response to the public comments it received on both documents.

Questions? Contact Sean Dunn of the MassDEP Air Assessment Branch in Lawrence: sean.m.dunn@mass.gov

Additional Resources for

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