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The Art and Science of Smoke Management with the Montana/Idaho Airshed Group

by Erin Law, Program Coordinator

Most forest landowners are keenly aware of the advantages to being able to burn forest debris.  Unfortunately, the disadvantages are also keenly felt when a burn does not proceed as planned.  The Montana/Idaho Airshed Group was formed by professional fire managers who burn significant acreage every year and air quality specialists who protect public health to prevent one of the most common outcomes of a burn gone bad – smoke impacts to surrounding residents.
Members of the Airshed Group analyze the amount of fuel in their burn units and each burner enters detailed information regarding how those fuels are arranged across the landscape into a database they access from the internet.  This database, called the Airshed Management System, or AMS, ( catalogs each burn and its data and displays each burn location on a Google-based map.  The location and fuel information for each burn are then evaluated with the air quality and weather forecast to make a daily go/no go call for each burn unit based on whether the burn is expected to cause smoke problems.

From the burners’ perspective, the objective of the daily decision is to make sure they get a ‘thumbs up’ when smoke will disperse well.  From the Department of Environmental Quality (DEQ) regulatory perspective, the objective is to shut down burns that might cause public health impacts.  While it may seem like one accomplishes the other, in actuality those are two distinct analyses made successful by conditions at opposite ends of the fire environment spectrum.

The science at each extreme is pretty straight forward.  When air quality monitors (Montana –, Idaho – indicate that smoke amounts are approaching health thresholds, burning is restricted.  When air quality is good and the forecast indicates continued good dispersion, most all burning is approved.  The art of the decision comes into play when environmental conditions are somewhere between the two, a common occurrence during fall burn season.

Many factors determine which burn units can be lit safely when dispersion conditions are less than ideal.  Obviously, the location of the burn is very important.  How far smoke will have to travel before it may affect people is related to many factors including the volume of slash, how old it is, how dry it is, how much of it is large logs in contrast with smaller sticks and twigs or duff, and how it will be ignited.  Depending on the season, this assessment may also have to factor in anticipated wildfire smoke, smoke produced by agricultural burning, small residential open burning and woodstove smoke to adequately  protect air quality.  These variables are not quantifiable but nevertheless must be considered in context with the weather forecast to estimate future total smoke load from proposed prescribed burning.

Each day, a brief discussion occurs between the Airshed Group’s fire behavior specialist and each state’s DEQ smoke management staff to review current and forecast air quality and the following day’s proposed burn activity.  The two parties jointly assess potential impacts and determine whether burns will need to be restricted.

The Airshed Group enjoys a high level of commitment to protect air quality from each of its member burners, and each state’s smoke management staff is fully supportive of the prescribed burning program.  As a result, the cooperative nature of the MT/ID Airshed Group daily decision process has resulted in an extremely high success rate at both allowing burns that wouldn’t present problems and restricting those that probably would.  It is this spirit of cooperation that is the highest art, and its results can be appreciated by all the residents of Montana, Idaho, and downwind!

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