Columbia Valley had bouts of poor air quality off and on during November, according to the Northwest Clean Air Agency.

An agency monitor has been detecting air in the unhealthy range for fine particles periodically since Nov. 7. Fine particles in the air can be harmful because inhalation can cause damage to delicate tissues.

"Unhealthy" is one of six categories used to describe air quality in the state: good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy and hazardous.

The Northwest Clean Air Agency sent a notice to Columbia Valley residents asking them not to burn wood for heat or recreation during poor conditions.

Conditions are expected to improve as windy weather picks up this weekend. In the evenings, though, air quality is often worse in the area because more people are home using wood stoves, and cold weather and nearby mountains can trap smoke close to the ground.

Residents can check air quality conditions at nwcleanair.org/airquality/current.asp.

Reach ZOE FRALEY at zoe.fraley@bellinghamherald.com or call 756-2803.