Marvin Trotter, County Health Officer, said visibility was at a paltry three quarters of a mile.

"When it's that low it's considered hazardous," he said. "Bombers can't land here. It is considered hazardous. Most of the problem is with particulate less than 10 microns. It goes right to air sacs so in general surgical masks don't help."

Trotter said the smoke is expected to last for at least three weeks and would continue to worsen in areas of lower elevation.

"It is worse in Ukiah and Anderson Valley and it's worse at night," he said. "Things were better when things were hotter. It's going to be a problem for about three weeks. Close your doors and windows. People can also get a hepa filter to clean air indoors. Also you can use ceiling fans. There is Carbon monoxide, benzene--a lot of things in the air. The tiny little pollutants that have been burned is the biggest problem."