The National Weather Service has issued an air stagnation advisory, warning that atmospheric conditions likely will cause pollution to build up in the Rogue Valley.
High pressure is building over the region, trapping air in the valley, forecasters say. With little movement of air, the amount of airborne particles, including those emitted from wood burning and vehicle exhaust, will increase. Air quality is expected to decline.
Meteorologist Sven Nelaimischkies said the weather service coordinates with local air-quality authorities to determine when advisories will be issued.
The Oregon Department of Environmental Quality air-quality monitor in Medford showed the city's air quality was good at noon, but was rated unsafe for sensitive groups over a 24-hour period.
Jackson County air-quality officials have declared today a red day, which bans the use of non-certified woodstoves and requires no visible smoke from certified stoves.
The next significant storm that could blow out the stagnant air is expected to arrive late Wednesday.
— Anita Burke