Montana Department of Environmental Quality About Us Permitting & Operator Assistance Public Participation

Air Quality Monitoring  

Program Overview

The Purpose of Montana’s ambient air monitoring network is to monitor, assess and provide information on statewide air quality conditions and trends as specified by the Montana and Federal Clean Air Acts. The Air Quality Monitoring Program works in conjunction with local air pollution agencies and some industries, measuring air quality throughout Montana. This data provides the factual basis for regulatory decisions as well as provides air quality information to our local counterparts and the public.

Air Quality Monitoring Contacts

Air Main

Main Phone 
(406) 444-3490

FAX (Helena)
(406) 444-1499

Air Program Contacts

Air Quality Monitoring Section
(406) 444-6695

Annual Emission Inventory/Compliance Data - Point Sources
(406) 444-2742

Air quality information is provided on This site displays particulate concentrations and health effects for particulate matter less than 2.5 microns in diameter. This information is measured by monitoring equipment located throughout the state. The NowCast air quality concentrations are measured against health effect categories to provide a snapshot of the severity of impacts in your location. Concentrations are updated at 15 minutes past the hour at all stations. The most recent data displayed is the average particulate concentration measured over the previous hour.

For those counties with air quality programs using averaging times beyond the 1-hour average concentration of PM2.5 in issuing air quality alerts, an alternate data tool is under development which will address these data needs and is scheduled for release around the mid-December timeframe.  Additional information regarding this tool will be provided in the near future.  In the meantime, 1-hour average PM2.5 ambient monitoring data from all stations is available from Today’s Air or the Montana Data Portal for calculating longer average periods.

Recommendations for Outdoor Activities

Wildfire season can frequently coincide with outdoor activities. The Departments of Health and Human Services and Environmental Quality have developed guide to help you make decisions about outdoor sporting events when air quality is a concern.

Recommendations for Outdoor Activities >>

The procedure for making personal observation to determine the forest fire smoke index value for local areas without National Weather Station (NWS) or Department of Environmental Quality (DEQ) monitors is:
  1. Face away from the sun.
  2. Determine the limit of your visible range by looking for targets at known distances (miles).
  3. Visible range is that point at which even high contrast objects totally disappear.
  4. Use the values below to determine the local forest fire smoke category.
Health Guidelines
Health Effects Categories Visibility Ranges (miles)3
Hazardous Less than 1.3
Very Unhealthy 2.1 - 1.3
Unhealthy 5.0 - 2.2
Unhealthy for Sensitive Groups 8.7 - 5.1
Moderate 13.3 - 8.8
Good 13.4 +


DEQ Site Visit - NCore Station
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