PORTLAND, Ore. (KOIN) — Multnomah County officials instituted a ban on wood-burning Wednesday, citing the extreme heat and poor air quality as significant health hazards.

The ban on smoke from burning wood goes into effect at noon and will be lifted “when conditions improve,” officials said. While it does not apply to cooking, the county’s website says it applies to wood or pellet stoves, fireplaces and chimeneas. Some households can apply for an exemption.

It comes one day after the Oregon Department of Environmental Quality issued an air quality advisory for heavy levels of ozone pollution, otherwise known as smog. A similar ban was also issued Monday from the Multnomah County Fire Defense Board, which prohibited using recreational campfires, fire pits and burning yard debris in the name of fire safety.

The DEQ said ozone forms when hot temperatures and low winds combine with pollution from cars, gas-powered engines and chemicals in paints and aerosols. These pollutants then react with sunlight and heat to produce ozone and haze.

Air with high levels of ozone pollution is unhealthy to breathe, and officials hope to reduce it by keeping residents from adding to the emissions by burning wood, driving, mowing the lawn and using aerosol sprays.

This week’s high temperatures and sunlight can exacerbate air pollution, health officials said. As the day gets warmer and brighter, ozone pollution increases. Pollution levels tend to be highest during afternoons and early evenings.

Officials urge community members to check in on groups that are sensitive to air pollution, such as children, people over 65 and those with respiratory problems like asthma and COPD.

The DEQ’s Air Quality Index has up-to-date information on the current air quality conditions.