Multnomah County today issued its first ban in 2019 on using wood-burning fireplaces.

Stagnant air and pollution have made today's Portland air unhealthy for sensitive groups—children and elderly and those with heart and lung conditions. Beginning at noon, county officials prohibit Multnomah County residents from using fireplaces, unapproved wood stoves, pellet stoves or any outdoor burning devices until the restriction is lifted.

This is the second air quality advisory in two months. Last month, however, a county alert called only for voluntary burning restrictions. This one is mandatory.

This is also the first burn restriction to be called under a new county ordinance passed in January 2018, which outlines how county officials monitor air quality conditions and enforce restrictions.

"Winter wood smoke is a major contributor to air pollution, with significant harmful impacts to people who are vulnerable like small children, seniors and people with respiratory or heart conditions," environmental health director Jae Douglas said in a statement. "As we head into the holidays, please be mindful of those folks in our community who really suffer from poor air quality, and wait to burn wood until conditions improve."

Some burning is allowed if wood is the household's only source of heat; if the household income is 60 percent or less than the Oregon median income; if a power outage interrupts or shuts off a primary source of heat; and if food is being cooked with a wood-fired grill, smoker or charcoal grill. People can apply for exemptions at multco.us/woodsmokestatus.

Portland is currently ranked among the top 25 cities with the most short-term particulate pollution, according to a 2019 American Lung Association study. Residential wood burning is the city's largest source of particulate pollutants.

Kate Willson, a county spokesperson, says conditions are expected to improve by tomorrow but officials will know more about when the restriction will be lifted in the morning.