Ozone Season ends on a low note

With the end of November comes the official end of ozone season in Houston, which runs from March 1 through November 31. (Once the new 2015 ozone standard is implemented, Houston will no longer have an “ozone season.” At that point we will monitor for compliance with the federal ozone standard year round.)

So, how did we do?

Short answer: not well.

First, keep in mind that ozone pollution has improved dramatically since the ’70’s and ’80’s. As this lifelong Houstonian knows, anyone who’s lived here for any length of time (and opposes further air pollution regulations) loves to point out what great improvements we’ve made in ozone pollution.

And indeed we have. Just compare this plot of daily ozone values in Houston in 1984:

Ozone 1984


With this plot of daily ozone values from 30 years later, in 2014.


Ozone 2014


So in thirty years, we’ve gone from more than 200 ozone days a year to two or three dozen. (By the way, if you like plots like the above, you can generate many more of them on the EPA’s AirData webpage.)

But two or three dozen high ozone days is still two or three dozen days with more asthma attacks, more heart attacks, and yes, even more premature death. So while air quality has gotten better in Houston, any amount of ozone days is too many.

So how did we do in 2015? Not well. After a record low fourteen ozone days in 2014, this year saw 31 high ozone days. The following chart plots high ozone days (“Ozone Violations”) and ozone forecasts (“Ozone Action Days”) for the last three years.


Ozone 2013-15


All this means that ozone pollution is still highly variable in Houston. We had a good year in 2014. But remember that while globally 2014 was the hottest year on record, it was unseasonably cold for the Eastern United States, as this map from the National Oceanic and Atmospheric Administration beautifully illustrates. (Now feels like a great time to remind everyone of that time James Inhoff threw a snowball on the Senate floor.)

So a cooler-than-average 2014 in North America may have had something to do with Houston’s strong ozone season that year.

As for 2015, does anyone remember August? If you don’t, hop on over to houstoncleanairnetwork.com and check out August 1st. Or August 2nd. Or Augusts 3rd, 10th, 11th, 12th, 13th, 14th, 15th, 24th, 25th, 26th, 27th, 28th, 29th, and 30th.

Not a good month for ozone pollution. Not a good year either.

One silver lining in all this: the Texas Commission on Environmental Quality does seem to be getting better with its “Ozone Action Day” forecasts. The TCEQ predicts one day in advance whether it thinks that ozone pollution will be a problem in Houston. Strictly speaking, the TCEQ gets its forecasts from the EPA, but I like to give our beleaguered state agency credit when I can. (You can check the ozone forecast and sign up for email alerts here, although in a few sentences I’m going to offer a better suggestion.) We have previously reported that TCEQ correctly predicted about one-third of high ozone days in 2013 and one-half in 2014.

In 2015, I am proud to say that TCEQ correctly predicted 77% of the 31 high ozone days. This is an impressive record, and I won’t speculate on whether it’s just the product of chance, as the recent annual trends in ozone pollution seem to be.

In fact, I won’t say much about Ozone Action Day forecasts at all. Because there’s a better way! You don’t have to rely on forecasts. You can use our tool, the Houston Clean Air Network, to get real-time ozone data. You can even download the Houston Clean Air Network for iPhone or Android.

Because these resources offer you ozone data in REAL TIME, you don’t have to rely on forecasts. So yes, 2015 was a worse ozone year than 2014. And yes, the TCEQ seems to be getting better at predicting ozone days. But our message stays the same: if you want to limit your exposure to ozone pollution and protect your health, use our free tool, the Houston Clean Air Network.

We’ll see you next ozone season!