Summary

Texas Gov. Rick Perry cites partly cloudy statistics to back up his boast that Texas is doing just fine cleaning its air on its own — without the EPA.

Perry boasts that "we cleaned up our air in Texas more than any other state, during the decade of the 2000s." But that's based on homemade statistics compiled by Texas officials, who only counted measures from Houston and Dallas and left out cities where there was less improvement. State officials say their method is "scientifically defensible," but EPA and environmental groups disagree.

While no one debates that Texas made significant strides in the 2000s, it's also true that with some of the nation's worst air quality, it had a lot of room to improve. And despite its gains, Texas' air still ranks among the most polluted in the U.S. in a number of categories.

Perry said that in Texas, "we lowered our nitrogen oxide levels by 58 percent." But that's counting only "point source" emissions, largely from industrial and power plants. Total nitrogen oxide emissions — including those from "mobile sources," such as cars — have been reduced by a far more modest 16 percent in Texas, according to EPA calculations. That overall reduction is lower than the national average.

Analysis

Perry has cultivated an adversarial relationship with the Environmental Protection Agency going all the way back to his days as Texas' agriculture commissioner. Perry contends the "mandates and overreaching regulation" of the EPA cost Texas jobs and that Texas is better equipped to tackle air quality issues than "a centralized, all-knowing, one-size-fits-all federal government." And, he says, Texas has done just fine cleaning up its air without the EPA's interference (a claim many environmental groups in Texas contest).

One of Perry's most heated battles with the EPA is over global warming and the Obama administration's use of the Clean Air Act to regulate greenhouse gas emissions from the state's many oil refineries and power plants. Perry is skeptical of scientists who say global warming is a man-made problem. Tensions reached a boil when, earlier this year, the EPA announced it was taking over control of the greenhouse gas permitting in Texas because the state refused to implement its rules. Texas has led several other states in a legal challenge to the global warming regulations. The issue is still pending in federal court.

At a town hall event in Derry, N.H., on Sept. 30., an audience member asked about global warming, and Perry repeated his skepticism and defended Texas' environmental record:

Perry: And we in Texas have addressed this. You realize that we cleaned up our air in Texas more than any other state, Mike, during the decade of the 2000s.

The audience member then suggested that was due to EPA regulations.

Perry: No, it wasn't the EPA regulations. As a matter of fact, they tried to come into Texas after we cleaned up our air and take it over and what they'll do is just kill a bunch of jobs and won't clean up the air at all. We lowered our ozone levels by 27 percent during the decade of the 2000s and we lowered our nitrogen oxide levels by 58 percent.

Did Texas really outpace all other states in cleaning up air pollution, and do it in spite of the EPA? Did Perry really cut nitrogen oxide by 58 percent? Here we look at Perry's claims one at a time.

Texas Tops in Cleaning Its Air?

Let's start with Perry's claim that Texas cleaned up its air more than any other state during the decade of the 2000s.

This claim is based on a report, "Texas Air Quality Successes," from the state government's Texas Commission on Environmental Quality, which said that Texas lowered its ozone levels by 27 percent.

TCEQ report: From 2000 to 2010, ozone levels in Texas have decreased by 27 percent statewide. By comparison, the rest of the nation averaged only a 14 percent decrease in ozone levels over this same time period.

This is a TCEQ custom-made statistic that may not mean what you think it does. The EPA doesn't report air quality at the state-wide level. Rather, it uses more localized measures to track ozone levels, relying on a series of monitors placed around various metropolitan areas.

The TCEQ did not attempt to calculate some state average and compare it with other states. Among all the monitors in the state, it selected the one with the fourth-highest eight-hour ozone concentration. It was then averaged with the fourth-highest monitor values from two previous years. That then became Texas' statewide value. All of the monitors ended up coming from either Houston or Dallas, TCEQ officials said. That value was then compared with an average of fourth-highest monitor values from the beginning of the decade, and ultimately with other states using the same methodology.

According to this TCEQ measure