blog posts Chicago air is dirtier in July than smog-choked L.A. and more bad air is forecast Jul 10, 2020 10:15 am by Chicago TribuneIllinois in the News Share on Facebook Tweet Email Images Chicago Tribune (July 9) 'We are seeing an ever-increasing number of warmer days where it is more likely to have larger ozone production and other air quality issues,' says U. of I. atmospheric sciences professor Donald Wuebbles. Share on Facebook Tweet Email