So far, the Rim fire at Yosemite National Park's western doorstep hasn't smoked out the San Joaquin Valley. Pray the wind doesn't shift.
If you've seen the photographs of the immense pyrocumulus clouds erupting over the Sierra, you know it's an intense, fast-moving wildfire.
Pyrocumulus clouds occur with the high heat of volcanoes and wildfires. They look like cauliflower, rising tens of thousands of feet high with ash and vapor.
I've talked with fire experts who say you can see these clouds for 100 miles in all directions.
This is the biggest fire in the Stanislaus National Forest in at least a generation, now approaching 180,000 acres. On Tuesday, it ranked as the seventh largest on record in California.
The ash and soot have been riding the wind into places north of the fire, such as Reno and Sacramento. In Sacramento, the standard for PM-2.5 — think soot — has been breached nine times this month. Add up all of Sacramento's PM-2.5 exceedances in August over the last decade, and the total wouldn't equal this month.
Here in the Valley, which sometimes is socked in with wildfire soot, there haven't been any PM-2.5 breaches in the standard. Ozone is not nearly as bad as it has been in most Augusts.
Keep an eye on the weather and trust your nose. If you smell smoke, the wind may have changed direction. This fire may burn for many weeks to come.
Will the Valley finally achieve ozone standard?
By October, people in the San Joaquin Valley may not be carrying an extra $29 million debt for missing the old federal one-hour ozone standard.
It appears the Valley could achieve an ozone standard for the first time. This standard dates back decades. An EPA reference indicates a final decision on Feb. 8, 1979, to enforce it.
Pick the reason for the improvement: public awareness, billions of dollars spent on pollution control by businesses, landmark local air rules, cleaner fuels, cleaner cars, environmental lawsuits, good weather, better luck — all of the above.
If it happens, it will be memorable.
Until the last six or seven years, the Valley wasn't even close to making any kind of ozone standard — federal, state, eight-hour, one-hour.
The Valley still has a tough road ahead to make the federal eight-hour standard in the next decade.
This month, the San Joaquin Valley Air Pollution Control District issued a report that looked back 17 years to see the Valley's progress with the one-hour standard. In 1996, the Valley spent 56 days over the one-hour standard. In 2012, it was three. So far this year, it's zero.
August has been memorable already. Through Monday, there had been 13 days this month when ozone didn't exceed either federal standard — the more stringent eight-hour or the old one-hour.
Dating to 1994, there hasn't been an August with more than 10 good days.