A "high smog day" is any day with a "ground level ozone ... [of] more than 75 parts per billion." By those standards, the Los Angeles air is improving, dropping from 92 high smog days during last year's "peak smog season" (May to October) to 82 days this year, says a new South Coast Air Quality District survey. A rep for the air quality district tells KPCC that lower-emission cars and programs that curb air pollution helped bring the numbers down, as did the rare instances of rain, which cleans the air.
The numbers probably won't be so good next year. A new EPA standard going into effect in late December will drop the acceptable amount of ozone down to just 70 parts per billion, and that moves a lot of days from the "not so smoggy" category into the "too smoggy" one. Using the new threshold, the region's 82 bad air days would rise to 112 days. The district's working on plenty of new programs to help reduce smog even more, and they also have until way off in 2037 to meet the new standards.
· Smog declined in Southern California over the last year [SCPR]