Department of
Environmental Quality

Wildland fires are fires that occur in undeveloped areas including public forests and rangelands, woodlots, and private timberlands. Wildland fires can be further categorized as either wildfires or prescribed fires.

Wildfires

Wildfires are either managed for resource benefit (wanted) or suppressed (unwanted).

• Wildfires that are managed for resource benefit are fires that achieve management objectives such as reducing wildfire risk, preparing sites for replanting, thinning, recycling nutrients, reducing pathogens, and improving forage. They may be allowed to burn if adequate resources are available. Usually, lightning naturally ignites this type of wildfire.
• Wildfires that are suppressed are fires that do not meet management objectives. They are typically suppressed by fire management agencies. These wildfires are often due to negligent human behavior such as smoking in forested areas or improperly extinguishing campfires. They may also be caused by intentional behavior by arsonists. The Federal Emergency Management Agency (FEMA) reports that more than four out of every five forest fires—representing nearly half of the acres burned each year—are started by people.

Prescribed Fires

Management-ignited fires on wildlands are called prescribed fires. Similar to beneficial wildfires, prescribed fires are conducted to meet forest and rangeland management objectives.

In Idaho, land managers who conduct a "major" amount of prescribed burning participate in a bi-state smoke management program with Montana. The program is managed by the Montana/Idaho State Airshed Group, which was formed to limit the impacts of smoke generated from necessary forest and rangeland burning.

The Idaho Department of Lands (IDL) requires a permit for all open fires on any forest or rangeland during the closed fire season, which is generally May 10 through October 20. This requirement may be year-round in some areas. More stringent local ordinances also may apply, so contact your local fire department or district for more information. The Idaho Forestry Act, enforced by IDL, requires slash created by forest harvesting practices on state and private lands to be treated. The most common treatment technique involves burning the slash during periods of low fire danger. Check with IDL for further information about fire management activities.

Wildland Fires and Your Health

Smoke generated by wildland fires can pose a major health risk. It is primarily made up of small particles, gases, and water vapor, with trace amounts of hazardous air pollutants. Most harmful are the particles (or particulate matter) smaller than 2.5 micrometers in diameter (70 micrometers is the diameter of a human hair). If these particles are inhaled deeply into the lungs, they can damage lung tissue and cause respiratory and cardiovascular problems.

Symptoms from short-term smoke exposure range from scratchy throat, cough, irritated sinuses, headaches, runny nose, and stinging eyes to more serious reactions among persons with asthma, emphysema, congestive heart disease, and other existing medical conditions. Older adults and children are also high-risk groups.

Visual Smoke Observation

DEQ monitors air pollution in population centers throughout the state to ensure that air quality standards are being met. When real-time data are available, knowing the air quality for the day and how it will affect our health is a relatively easy matter. Monitoring smoke levels from wildland fires is difficult, however, because these fires usually occur in remote areas and the smoke impacts are transitory. Because wildland fire smoke is highly visible, it is possible to visually estimate smoke levels and estimate potential health impacts. Generally, the worse the visibility, the worse the smoke.

Use the table below to evaluate air quality conditions, identify potential health effects, and determine appropriate exertion levels based on the visibility range. Do not use this table when relative humidity is above 65%. Make a visual observation as follows:

Acknowledgement: Visibility ranges adapted from data compiled by the Montana Department of Environmental Quality and U.S. Forest Service. Health categories and effects established by U.S. EPA.