Dallas smog aerialIt's only a proposal, but the Obama Administration's plan to cut sulfur in gasoline is aimed primarily at drastically reducing smog-forming Nitrogen Oxide, Volatile Organic compounds and Particulate Matter, the major pollutants that causes DFW to have such bad "ozone seasons."  Would it reduce it enough to finally put the region in compliance with the Clean Air Act? Good question.

Sulfur content in gasoline would drop from the current standard of 30 ppm to 10 ppm by 2017 – one year before the compliance deadline for the tougher 75 parts per billion national ambient air ozone standard. That's not a coincidence. The EPA hopes that this initiative is going to drive urban ozone clean-up throughout the country, even in stubborn dirty air hot spots like DFW, which hasn't been in compliance with a smog standard since it was created over 20 years ago.

Along with new stricter emission standards for cars that have already been implemented, the pollution from cars will be coming down over the next decade to historic-per-vehicle lows. Since forever, the state of Texas and local officials have put almost all the blame for DFW's poor air quality on cars. So does this mean that we might actually have a chance to breathe safe and cleaner air, by say, 2020?


First, there's the question of continued growth. If per-car emissions go down, but you're importing 120,000 more cars every year into North Texas, the decreases in emissions are being canceled out to some degree. In this respect, DFW has been its own worst clean air enemy. By attracting new residents year after year and, for the most part, not creating successful transportation options other than private vehicles, the Metromess dooms itself to more total car pollution.

Then there's the climate. Everyone knows how unbearably hot it can get in DFW during July, August and September. That heat and sunlight is one reason we have a smog problem – it chemically transforms the Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOCs) into ozone. What if it gets hotter, and drier? When the ground can't cool off at night and you start out with high morning temperatures that will only get worse by 5 pm, you know it's going to be a bad air day. The more days like that, the harder it's going to be to have safe and legal air despite the changes in engine design and fuel specs. So climate change could rob us of some of those automobile reductions.

If the last couple of years are any indication, you also have to wonder how much of those vehicle changes will be lost on DFW because we live in the Barnett Shale. 16,000 gas wells that are relatively short-term air polluters are being supplemented with more processing infrastructure like compressors, refineries, and pipelines that are year round polluters. Last year's Houston Advanced Research Consortium study estimated the impact of even a single compressor or flare to be as much as 3-10 ppm within five to ten miles, something it would take thousands of cars to accomplish. Even if those cars aren't there anymore, or their emissions make them less of a clean air threat, you have these decentralized major sources taking up the slack. This is one reason why the state itself told EPA that last year there was more VOC air pollution coming from oil an gas sources in North Texas than all the area's on-road cars and trucks, and a large contributing cause to why air quality has been getting worse in DFW over the last two years.

It's not just the number of these facilities but their physical location as well. The more the gas industry moves eastward, the more of the DFW core urban area is "downwind" of these sources, the more the pollution from these facilities combines with car emissions and other urban sources, and the longer they take to leave the now 10-county "non-attainment area," meaning they linger, exposed to sunlight and heat, and have more opportunity to create high levels of ozone. If you have more flares and compressors within 1 to 3 miles of one of 18 or so state air monitors – you will probably begin to see higher ozone readings as a result of their operation –  as you have the last couple of years. Most of these pipelines and processing facilities have come online only since 2006.

And that's just in the North Texas area. There's evidence to suggest that the gas industry's building-out to the southeast – or upwind – of DFW is also affecting our air quality. In the same way that Houston's air pollution is said to make our initial "background" ozone levels higher, so too the 60-100 compressors in Freestone County, about 90 miles southeast of Dallas also feed their under-regulated "Standard Permit" pollution into the DFW urban mix. As does the Haynesville Shale gas play itself, as do the remaining east and central Texas coal plants and so forth. If sources to the south and east continue to increase their emissions, it means DFW starts from further and further behind, so that even if cars get cleaner, they might not get so clean so fast as to compensate for this imbalance.

Then there's the "fire hose" effect of the three Midlothian cement plants sitting so close to one another as to create one large super plume that's usually pointed toward the DFW urban core most of "ozone season." Because of citizen efforts, those cement kilns are substantially cleaner in 2013 than they were as recently as 2008. All but one wet kiln is closed, and that one is due to shut down next year. None are burning hazardous waste. But they're still the largest stationary sources of pollution in North Texas – including emitting copious amounts of NOx and VOCs – and they can still impact monitor readings miles and miles away. It's unclear what impact the burning of newly-permitted "non-hazardous" industrial wastes like car parts and plastics in the Midlothian kilns will have on the formation of smog-forming pollution.

EPA estimates an 80% drop in VOC and NOX pollution from cars as a result of its new low-sulfur fuel rule. That's steep. Remove that amount of pollution from all DFW's cars and trucks, and you'd expect to see a substantial improvement in air quality. That's what you'd expect. But, depending on a lot of other variables the state and federal government may or may not be interested in fixing, it could take more than this proposal to bring DFW into compliance with the new 75 ppb ozone standard that is now the federal definition of safe and legal air.

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