Earlier this month, I asked whether CDPHE (a.k.a., “the Department”) is cooking the books on Colorado ozone. In particular, it struck me as suspicious that the Department used data from 2006, an anomalously active wildfire season, as inputs for models used to project ambient air concentrations of ozone through 2020. You can read all about it here, but in a nutshell, wildfires inflate ozone, so the CDPHE’s use of the second-most active wildfire season on record as a constant in an ozone model is inappropriate…unless, of course, it was trying to exaggerate the threat of a federal crackdown on air quality in order to, say, pass legislation that mandates fuel switching, like HB 1365. Remember, the Denver-area’s non-attainment for federal ozone regulations was a major reason put forth by the Ritter administration in support of Clean Air Clean Jobs Act.
**Here’s the Wikipedia entry on ozone; for this post, all you need to know is that nitrogen oxides (NOx) are a primary precursor for the creation of ozone
In the two weeks since I wrote that post, I’ve become even more suspicious of the CDPHE’s ozone practices. Here’s why. On page 1-4 of the “2015 and 2020 Ozone Projections for the Denver Area,” ENVIRON (the modeling company) explains that input data for NOx emissions was provided by the Department. On page 2-24, EVIRON states that NOx emissions from point sources were projected to increase 23% by 2015 and 46% by 2020. So CDPHE told the modelers that NOx was expected to increase in Colorado.
But that’s not what the Department suggested eighteen months ago. Take a look at pages 5 and 6 of this February power point presentation by the Air Pollution Control Division (which is part of CDPHE), titled, “Colorado NOx Evaluation for Regional Haze and Ozone.” In it, the Division estimates that point source NOx emissions will decrease by almost 15,000 tons per year over the next decade, due to pending regulations. That’s about 15% of current NOx annual emissions from point sources in Colorado (118,000 tons per year). Given these projected decreases in NOx emissions, it’s not readily identifiable why the Department would tell the ozone modeling company that NOx emissions will increase by 46% through 2020. Where are all these big NOx emitters coming from?
Indeed, CDPHE has since conceded that its NOx inputs were way off base. On May 7, 2010, CDPHE’s Mike Silverstein gave a power point presentation titled “Air Quality Modeling Overview and Preliminary Ozone SIP Modeling Results” to the Regional Air Quality Council. On Page 19 of the ppt, Mr. Silverstein described the 2010 modeling “improvements.” Among them was “assumed more realistic growth in major NOx sources.” By the CDPHE’s own admission, then, it exaggerated the NOx.
The results of the “more realistic” NOx inputs were very significant (compare pages 21 and 15 to see the difference made by the NOx exaggeration): Ozone concentrations decreased by almost 5 parts per billion (almost seven percent). For comparison, consider that HB 1365 would only decrease ozone concentrations by less than one part per billion. That is, CDPHE’s NOx exaggerations impacted projected ozone concentrations more than 5 times more than the Clean Air Clean Jobs Act!!! (To see the impact on ozone of HB 1365, see page 5 of this presentation by Paul Tourangeau, director of the Air Pollution Control Division).
Remember, we still don’t know the significance of the ozone overestimations that I detailed in my first post!
William Yeatman is an energy policy analyst at the Competitive Enterprise Institute