It bears repeating: The dirty truth about burning wood

By Ashley Miller

Utahn’s are getting the message.

Wood smoke contains over 200 chemicals and compounds, including carbon monoxide, benzene, formaldehyde, sulfur dioxide, nitrogen oxides (NOx), dioxins and polycyclic aromatic hydrocarbons (PAHs). Woodsmoke is strikingly similar to cigarette smoke. The EPA estimates that a single fireplace operating for one hour burning just a few logs, or roughly 10 pounds of wood, will generate 4,300 times more PAHs than 30 cigarettes. The EPA further estimates that the lifetime cancer risk from wood smoke is 12 times greater than that from an equal volume of second-hand tobacco smoke.

Wood smoke is particularly unhealthy due to the fine particles contained within. These particles are too small to be filtered out of our bodies by our natural defense mechanisms, like coughing and sneezing, so they travel deep inside our lungs and possibly even into our bloodstream. This can cause respiratory illnesses, cardiovascular disease and other health conditions.

What about EPA-certified woodstoves?

Under the 2015 New Source Performance Standards (NSPS), stoves are tested by an accredited laboratory, in a laboratory setting, to meet a particulate pollution limit of no more than 4.5 grams of smoke per hour. In May 2020, the NSPS limit for new stoves will be lowered to 2.5 grams of smoke per hour.

The actual amount of smoke coming from even an EPA-certified stove depends on several factors including the type of wood being burned, how wet or dry the wood is when burned, how much airflow is present, and how hot the fire gets. It’s also important to know that much more smoke is released at startup and shut down. Remember, the certification process happens in a laboratory setting under a very controlled environment. Once a stove leaves the lab and makes its way to a home, those laboratory settings remain… in the lab. Regular maintenance is required to keep EPA-certified woodstoves operating as efficiently intended.

The dirty truth? Even a well-functioning EPA-certified woodstove emits roughly 97 pounds of fine particle pollution annually, according to the Puget Sound Clean Air Agency. So even EPA-certified stoves must abide by the no-burn laws.


Are pellet stoves a clean alternative?

The short answer, no. Pellet stoves are a considerably cleaner alternative to even an EPA-certified woodstove, but a pellet stove still burns solid fuel, which results in significantly more pollution than a natural gas alternative or electric heat. Pellets burned in these stoves are typically made from compressed wood, and the process still results in incomplete combustion. The dirty truth? Pellet stoves emit roughly 27 pounds of fine particle pollution annually.

The bottom line: For a troubled air shed such as ours, using electric appliances, or burning natural gas for heat is a much cleaner choice. Burning natural gas for heat results in less than a sixth of a pound of pollution, annually.


The good news

A newly released study shows that the state’s efforts to address burning wood and solid fuel during periods of bad air is working. The collaborative study led by the University of Utah, Utah Division of Air Quality and the EPA looked at wood smoke pollution on Salt Lake City, Bountiful and Lindon air monitors from 2007 through 2017 and found a significant decrease in the chemicals leading to the formation of PM2.5 found specifically in wood smoke. Data from 2015 showed roughly 16% of the pollution on the air monitors was from wood smoke. Data from 2017 shows that the pollution coming from woodsmoke had decreased to about 7%. This decrease is attributed to enforcement of the area’s wood-burning restrictions along with educational campaigns.

Over the last two years the Division of Air Quality has also implemented wood-stove and fireplace conversion programs that will likely lead to an even further decrease in wood smoke pollution. Vouchers are still available through both programs. Anyone who has a wood-burning stove, fireplace or insert, and lives in the PM2.5 nonattainment areas, is eligible to apply for the vouchers under the programs.


What about barbeques and smokers?

Charcoal barbeques and various types of smokers that are wood- or pellet-fueled can really wreak havoc during the winter and summer months when PM2.5 and ozone pollution builds. Although solid fuel burning restrictions don’t apply if the primary purpose of the burning is for cooking food, choosing another method of cooking is the best idea. Smokers have become  fashionable in the last few years, but the effects of this exemption is unknown because the data from 2018 and 2019 has yet to be quantified.

There’s evidence that burning is still happening on no-burn days. If you just really enjoy the sound and comfort of a crackling fire, or the taste of smoked and barbequed meats, it’s important to adhere to the burn restrictions. The Division of Air Quality sets these days when the inversion begins to build. If you choose to burn wood or other solid fuel during this time, you are adding a lot of pollution into the air during times when the air shed can’t afford any unnecessary emissions.

And even though the cooking exemption exists, it’s not a good idea to run your smoker on a yellow or red air day. Wait until the air is better. If you’re really concerned about great air quality in our valley, don’t do it at all.


Ashley Miller, J.D., is the vice-chair of Breathe Utah. She is the vice-chair of Utah’s Air Quality Policy Advisory Board and

a member of the Salt Lake County Environmental Quality Advisory Commission.


*For more information, or to apply for the wood stove and fireplace conversion assistance

program, visit


Check out the Utah Air App or Division of Air Quality website to track burn restriction days.

This article was originally published on February 26, 2020.