The Truth About Ozone

Almost daily we hear in the media or in legislative committee rooms that “oil and gas is the largest contributor to ozone in Colorado.” It’s usually followed by an outraged call for industry “to be held accountable.”
But where is the data supporting this claim coming from?

Is it even true?

Let’s spend a few minutes unpacking the claim. The answer may surprise you.

Before diving in too much, it’s important to understand what ozone is and where it comes from. The U.S. Environmental Protection Agency (EPA) defines ozone as “a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth’s upper atmosphere, where it blocks UV radiation, and at ground level.”[1] The EPA also provides further insight into how ozone is formed, stating, “Ground-level ozone – what we breathe – is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds (VOC) and nitrogen oxides (NOx).”

Oil and gas don’t emit ozone. Industry -- along with cars, trucks, power plants, lawn mowers, leaf blowers, water heaters, and even pine trees – emits VOCs and NOx that may form ozone. How much ozone forms, and when and where, depends on the weather. Colorado state agencies use scientific models to predict ozone levels, and monitors to measure what is actually in the air. The models show that oil and gas cause only a small share of Colorado’s ozone -- less than vehicles, much less than emissions that blow into our state, and much less than what occurs naturally.
It is simply inaccurate to say oil and gas is the largest contributor to ozone pollution.

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