BOISE, Idaho -

A recycling center fire that on Monday pushed air quality in Boise to unhealthy for sensitive groups is contained but will likely continue to smolder for several days.
   
Boise Fire Department officials say the fire that's about the size of a city block is burning wood debris in a large pit at Diamond Street Recycling.
   
Authorities say the fire started for unknown reasons at about 2:30 p.m. Sunday at the facility near the Boise Airport.
   
An airport spokesman says smoke from the fire didn't cause operational delays but pilots on approach Sunday evening were instructed to use the airport's instrument landing system for low visibility landings.