Update: CBJ cancels air emergency after fireplace and wood stove burning were banned overnight

Sub-zero weather caused particulate matter to exceed national air quality standards, according to officials

Smoke emits from the chimney of a home in the Mendenhall Valley on Saturday, Dec. 20, 2025. (Ellie Ruel / Juneau Independent)

By Mark Sabbatini

Juneau Independent

Update 3:30 p.m. Sunday: An air emergency issued Saturday evening that prohibited fireplace and wood stove use in the Mendenhall Valley was cancelled late Sunday morning by the City and Borough of Juneau.

"Due to increasing air movement and improving air quality in the Mendenhall Valley, the City and Borough of Juneau has canceled its Air Emergency, effective immediately," an update posted at CBJ‚s website just before noon states. "The City would like to thank Valley residents affected by the Air Emergency for their cooperation, especially during the cold weather conditions."

Original story, posted at 8 p.m. Saturday: A ban on using fireplaces and wood stoves — although pellet stoves used for heating are still allowed — was issued by the City and Borough of Juneau on Saturday night due to particulate matter exceeding national air quality standards.

A CBJ notice posted at about 7 p.m. states the pollutants have exceeded standards for the past five hours and notes weather conditions are expected to remain much the same Sunday.

"On windless, winter days, normal atmospheric conditions can become inverted: a layer of warm air prevents cold air from escaping and acts like a lid, trapping woodsmoke and other pollutants in the Valley’s air," Dan Bleidorn, the city’s lands and resources manager, wrote in an email to the Independent. "This is known as an air inversion, and the natural ‘bowl’ shape of the Valley intensifies this condition."

Bleidorn, in response to a question about the ban’s impact on residents who primarily heat their homes using wood as fuel, noted CBJ code requires residences to be able to meet minimum heating standards without the use of a wood stove.

The ban area extends from Juneau International Airport north to the Mendenhall Glacier, west to Montana Creek, south along the east shore of Auke Lake, and includes the east half of the Mendenhall Peninsula, according to a notice at CBJ’s website.

"When inhaled, fine particulates from woodsmoke can lodge themselves deep into the lungs and bloodstream and significantly impact children, elders, and those with breathing difficulties," the website notes. "Staff will keep monitoring the concentration throughout the night and into tomorrow.  This emergency will be canceled as soon as the levels return to healthy standards."

Bleidorn noted CBJ ordinance calls for an air emergency “whenever the ambient concentration of particulate matter within the air pollution zone equals or exceeds thirty micrograms per cubic meter (ug/m3) averaged over a 24-hour period and will remain at or above 30 ug/mg if an emergency is not called.” He stated the current 24-hour average as of about 8 p.m. is about 34 ug/m3.

The last such emergency declared by CBJ was in 2019, according to Bleidorn.

Further updates about the alert are available from CBJ by calling 907-586-5252, option 4, or at CBJ’s Facebook page and website.

A record-cold temperature was set Friday at Juneau International Airport and the long-term forecast calls for similarly cold, dry conditions through Wednesday.

Temperatures in the Mendenhall Valley are expected to reach minus 15°F or below overnight Saturday, according to the National Weather Service Juneau. A similar low is forecast Sunday night, with highs during the day between zero and 5°F.

• Contact Mark Sabbatini at editor@juneauindependent.com or (907) 957-2306.