ROBERT SIEGEL, host:
Houses in Southern California are not totally clear of danger yet. Fires are expected to burn through this week. And the smoke and ash will linger in the area even longer. In San Diego today, the skies look mostly clear.
But NPR's Jeff Brady reports, small particles from the fires are still at high levels.
JEFF BRADY: Local media warned all last week not to exercise outdoors. And people who have asthma were advised to stay inside with the air conditioner on. But over the weekend, as the brown smoke from the fires cleared a bit…
(Soundbite of bat hitting ball)
BRADY: …some folks in Escondido just couldn't resist going out to play softball.
Unidentified Woman: Ooh. Nice.
BRADY: That's okay, says Dr. Tim Morris. He's a pulmonologist at the University of California at San Diego. Even he went for a quick run on Sunday.
Dr. TIM MORRIS (Pulmonologist; University of California, San Diego): It certainly would not have been wise to do that at all in the middle of the wildfires.
BRADY: Over the past week, emergency rooms and clinics have seen more patients complaining of breathing problems throughout the region. That's because the fires put particles in the air. People breathe them in and once down in the lungs, they start causing irritation. At the peak, Morris says they were six to eight times the normal levels of these tiny particles.
Dr. MORRIS: By tiny, I mean microscopic. You could fit about a hundred of these particles on the cut edge of a hair to give you some impression how small they are.
BRADY: So if you live in a city where there's a wildfire is that like visiting Uncle Harry who smokes cigars for a weekend.
Dr. MORRIS: Maybe it's like taking a long drive with Uncle Harry when he refuses to roll the windows down as he smokes his cigars.
BRADY: But in this case, Uncle Harry's car is a huge area - a couple of hundred miles up the California coast to San Francisco and Sacramento. Typically, off coast winds would blow the smoke into Nevada and Arizona.
But Lisa Fasano with the Environmental Protection Agency says even as east to west Santa Ana winds fanned flames, they also saved the inland states from the brown smoke.
Ms. LISA FASANO (Spokesperson, Environmental Protection Agency): At some point, there was sort of a circular pattern in the weather that developed. And so it blow out to sea and then it would blow up the coast, and the Bay Area saw some impact. And then, in fact, I believe even the Central Valley saw some impact as it kind of circulated around and came back out.
BRADY: Fasano says since the Santa Anas have died down, wind patterns have returned to normal. But now, there's less smoke coming off the fires. Fasano says the smoke often reaches farther than you'd think. There have been several times where air quality in the western U.S. has been compromised because of wildfires in Asia.
Jeff Brady, NPR News, San Diego.