Ozone Season Update: July Goes Out Like A Lamb; August Comes In Like a Lion

After an uncharacteristically mild June and July produced the best ozone season in six or seven years, August arrived to remind us what summer in Texas is supposed to be about.

Seven of 20 smog monitors saw their annual highs set last Thursday, August 1st, when temperatures begin to climb back to the triple digits, with the one at Arlington's Municipal Airport recording a regional 2013 high of 93 parts per billion.

Perhaps more worrisome is the fact that on the same day, the Dallas Hinton Street site by Mockingbird and Interstate 35 also set its annual high of of 87 ppm. That's the first time this season that a monitoring site so far east in the heart of the DFW central corridor has gone above the magical 85 ppb level. And it's at a site that had not been a problem for ozone until the last couple of years. The fact that it's still capable of reverting back to these kinds of readings despite the weather-driven reprieve this year is a bad sign. 

DFW hasn't yet achieved compliance with the 85 ppb standard for smog left over from 1997, and must meet a newer, tougher standard of 75 ppb by the end of the summer in 2018.

To date, four DFW monitors have had an "exceedence" of the old 85 ppb standard this year – Hinton, Arlington, Denton Airport, and Pilot Point. It takes four such exceedences to produce an official Clean Air Act "violation" that counts against the region's goal of "attainment" with the standard. So, four strikes and you're out.

By this time last year, we'd already achieved that level of non-compliance. As of now, we're still three bad air days away from that milestone.

On the other hand, all but two DFW ozone monitors have had one or more exceedence of the 75 ppb one, and in fact four have already had four or more of them – Fort Worth Northwest, Keller, Denton Airport and…Hinton Street. That's how tough the new standard is. Even after a two month head start of rain and cooler weather, DFW is already violating it at four monitors.

This week's forecast is calling for Texas-like August heat. If the wind drops below 10 mph, we should see smog levels rise again. Traditionally, August and September are among DFW's worst bad air months. Whether 2013 will be the first year to see no official violations of the old 85 ppb standard will depend on whether the next two months are as kind to us as the last two.