Texas air pollution study gets help from the Hurricane Hunters

Houston and Los Angeles rank as the two most polluted or cities in the U.S. To address the problem in Houston, a series of air pollution field studies have been run over the past decade in Texas to help understand the what is going on, and come up with the best emission control strategies needed to reduce ozone pollution levels. The TexAQS II Air Quality Field Study is that latest effort to do so. The field study, slated to run through September of this year, will take a broad number of surface based and airborne air pollution and meteorology measurements. A key tool in the study is one of NOAA's P-3 weather research aircraft, which will be specially outfitted as a state-of-the-art air pollution sampling platform. I flew on the NOAA P-3s in a number of such air pollution field studies during my stint with the hurricane hunters. My most memorable project came in 1989, when we flew over the Arctic Ice Cap to track "Arctic Haze". It was unbelievable to be flying over what should have been one of the cleanest places in the world, only to find visibility reduced to three miles in thick haze, due to pollution blown over the North Pole from industrial sources in Eastern Europe.


Figure 1. Areas of the U.S. in violation of the EPA standards for ozone pollution.

The data collected in the Texas study will be used to develop a variety of computer models needed to understand what is going on, and thereby recommend pollution control strategies. Ozone is not emitted directly, but is formed in a very complicated way from the "precursor" pollutants, Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOC). It turns out that this formation process is extremely non-linear--which means that in some cases, reducing emissions of one of the "precursor" pollutants will actually increase ozone. As a result, you really have to understand the problem thoroughly before going to the expense of implementing emission controls of NOx or VOC in an effort to reduce ozone pollution.

Computer modeling efforts to understand pollution are of limited help, because we don't have a very good idea about how much pollution is being emitted. Each year, businesses are required to submit estimates of how much pollution they are emitting. These emission estimates, however, are not very accurate. For example, according to a story published May 7 in the Houston Chronicle, a British Petroleum refinery in Texas City (just south of Houston) reported that it emitted three times more formaldehyde and ammonia in 2004 than in 2003. The increase in emissions at this one plant was so large, that it distorted the data for refineries nationwide, according to the EPA. The Texas City plant accounted for the bulk of a 15 percent increase in emissions in 2004 that drove refinery pollution to its worst level since 2000. The problem is that the company likely underestimated its 2003 emissions. The emission estimates are all theoretical, and are not based on actual measurements of pollutant gases coming out of the stacks.

The article quotes Matt Fraser, an associate professor in civil and environmental engineering at Rice University, who says: "It's incredible that they were that far off. That's a huge increase in formaldehyde. It just shows you how little attention is being paid to getting emissions numbers right. And since all of our air-quality control strategies are based on that data, it makes you wonder." Well, the planners of the TexAQS II Air Quality Field Study are also wondering, which is why there is the necessity of doing this field study. The only sure way to know what's really going up into the air is to go out and measure it, and this summer's study should help the scientists and regulators figure out what the right steps are to control air pollution in one of our most polluted cities.

Unfortunately, the participation of NOAA's P-3 in the Texas study means that only one P-3 will be available for hurricane hunting this hurricane season. This worries me, because the P-3s are the best tool we have for hurricane reconnaissance. The Air Force C-130s do not have the state-of-the-art radar systems like the P-3s carry, nor the new SFMR Stepped Frequency Microwave Radiometer instrument that can measure surface winds speeds anywhere in a storm. Will participation of the P-3 in this air pollution study save more lives and property than if the aircraft participated in hurricane hunting this Fall? I think that is probably the case, but it is definitely a gamble that I'm uncomfortable with.

Jeff Masters