The Fourth of July came and went without an ozone violation for the first time since 2000 -- one of only three times the air has been healthy on Independence Day in the last 20 years.

There was no stifling heat. The breezes seemed to stir the air just enough. And I did not see a dramatic spike in the particulate matter from fireworks, though I was looking at daylong averages, not the hourly readings.

We went from a perfect storm of pollution in late June -- among the most unhealthy weeks in decades -- to an improbable healthy-air day for the Fourth of July.

How healthy was it? The numbers look like the kind of readings you would see in March.

All that changed in a hurry this week. The wind has stopped. The crud is filling up the Valley's bowl. Time to protect yourself again by staying indoors during afternoon hours.