Wood Heating

Wood heating is the largest source of smoke (fine particle) pollution during winter. Making matters worse are the stable weather patterns during winter that trap smoke near the ground.

Today's new wood stoves burn much cleaner and efficiently, but how the stove is operated is the biggest factor in how much it smokes. The goal is to see only heat waves or just a wisp of smoke from the chimney. 

Review this brochure and watch this 5-min video on operating your wood burning device efficiently. 

Chimney Smoke

State law prohibits excessive chimney smoke. Smoke is measured as opacity. Smoke so thick you can't see an object through it is considered 100% opacity. Smoke is in violation when it obscures an object by more than 20%.  

smoke opacity levelsPictured on the right are smoke densities of 20%, 40% and 80%. 

After start-up, check the chimney. If you see more than heat waves, provide more air (open your damper) to the fire.  

Smokey chimneys may also be caused by burning firewood that has not adequately dried. Wood should be split, stacked and loosely covered to dry at least 9-12 months.

Manufactured logs and pellets may be burned in your wood burning device. Burning anything other than natural firewood or manufactured logs/pellets is prohibited under state law. 

Wood smoke is a complex mixture of fine particles, many of which are toxic and known to cause cancer. Breathing wood smoke can harm everyone, but children are most vulnerable because their lungs are still developing. Also at higher risk from wood smoke are infants, the elderly, and those with existing heart and lung ailments. Health-related studies are linked at the bottom of this page. 

Devices Sold, Installed

Wood burning devices offered for sale, sold, or given away to Washington residents must have testing data that it meets the more stringent state emissions standards, listed below. Before selling, purchasing or installing a wood burning device, check with Spokane Clean Air. A permit and inspection from your local building department is required to install a wood burning device. Lists of stoves, fireplaces and inserts that meet Washington Emissions Standards are linked from Ecology’s webpage.     

Type of Device

Washington State 
Emissions Standards
for newly built devices sold in our state

Catalytic wood burning devices 2.5 grams per hour
Non-catalytic wood burning devices 4.5 grams per hour
Factory-built fireplaces and masonry heaters 7.3 grams/kilogram

Temporary Burn Bans and Exemptions  

Temporary burn bans are issued when fine smoke particles become concentrated and are not readily dispersing due to weather conditions. The type of ban depends on the level of pollution and weather forecast. Burn ban details and exemptions to burn bans.

Health Impacts from Wood Smoke

Several studies have been conducted over the years linking fine wood smoke particle exposure to adverse health effects. A leading researcher on the topic is Dr. C Arden Pope III, of BYU. Below are materials from a webinar Dr. Pope presented on July, 28, 2011.