The state of Washington and the Spokane Regional Clean Air Agency on Friday issued stage-1 burning restrictions through at least 4 p.m. on Monday.
The restrictions limit indoor burning to stoves and fireplace inserts that are federally approved to minimize pollution.
The limitations under a stage-1 yellow alert follow a stagnant air advisory issued by the National Weather Service, also effective through Monday afternoon.
Outside of the Spokane urban area, state officials have banned the use of uncertified wood stoves and fireplaces in Spokane, Stevens, Walla Walla, Kittitas, Chelan and Douglas counties, due to poor air quality.
In North Idaho, a voluntary wood stove ban was requested.
In Washington, the ban applies to stoves and other wood-burning devices that don’t have pollution controls certified by the U.S. Environmental Protection Agency. Outdoor burning was also banned. An exemption is allowed for residential wood heating if the device is a family’s primary source of heat.
Higher air pressure over the Pacific Northwest has created conditions favoring the accumulation of smoke, dust and other pollutants in the lower atmosphere.
The main pollutant is wood smoke, which can irritate lung tissue.
People with lung conditions such as chronic obstructive pulmonary disease suffer increasing symptoms under higher pollution levels.
A 2009 study through the state Department of Ecology estimated that fine particles in the air contribute to about 1,100 deaths and about $190 million in health care costs each year in Washington.
Currently, cold air near the ground is trapped beneath layers of warmer air aloft, preventing the polluted air from moving away or being diluted by cleaner air from above.
“Weather forecast models predict very weak ventilation of the atmosphere,” said scientist Mark Rowe, of the Spokane clean air agency, in a news release. “All of this means deteriorating air quality for the Spokane area until the middle of next week.”
Stoves and fireplace inserts built in 1993 or later are approved as cleaner-burning and are labeled as compliant.
Officials said that having an approved device still requires proper burning technique. They recommend starting with a small, hot fire using seasoned and dry wood, then letting the stove or insert warm thoroughly before building a larger fire. The exhaust from the chimney or stove pipe should show only heat ripples and no visible smoke if the device is operating properly. If smoke does show, then increasing air flow and the intensity of the fire will eliminate visible smoke.
The burn ban does not apply on tribal reservations, where the U.S. Environmental Protection Agency has jurisdiction.