Summary of interagency working comments on draft rule under EO 12866.

These comments do not necessarily represent the views of OMB and are su bject to further policy review. 29. To improve clarity, it would be useful to move the request for information to the beginning of the document and include the rest as background. 30. When will the Santa Monica Study be ready? 31 . We recommend that EPA include t he following question s , to help EPA collect useful information on how regulation of avgas may cause commercial disruptions:  How many companies manuf acture AvGas today?  Do we have to import AvGas to meet current demand?  How is AvGas transported to airports? ( either piped into airports or by truck)  For companies developing alternatives, what is the best estimate as to when they ’d be able to meet current demand?  Where does the research stand on a standard for unleaded fuel for high
-performance engines?  To what extent are U.S. operators of general aviation aircraft concerned that any changes made to U.S. avgas requirements (such as, for example, requiring manufacturers to produce engines that consume non
- leaded fuels), could disrupt their ability to fly to/from locations outside the United States because of a potential lack of those non
- leaded fuels?  To what extent are U.S. manufacturers and other sellers of general aviation aircraft concerned that a change in U.S. avgas requirements could affect the international competitiveness of their products by , for example, decreasing the demand for U.S. aircraft overseas if they are not compatible with avgas used in those non
- U.S. markets? 32. Page 13 line 12: It is indicated that 100LL is the most commonly available type of avgas but it is not clear here if this is the most commonly used. Suggest noting this here and not later in the paragraph as it is presented. 33. Page 14 line 6: It is noted that if all avgas was 100LL, it would account for approximately 34,000 tons of lead emitted to the air . Would this be double if 100 octane only were used as indicated by the doubling of the concentration of lead in 100 octane relative to 100LL? 34. Page 17 line 8: It is mentioned that EPA has discussed it “endangerment finding” authority at length in rec ent notices. It should be noted here that these endangerment findings are with respect to green house gases and not lead. 35. Page 17 line 18: Concentrations of the standard are presented in text unites of micrograms per cubic meter but in previous and futu re text units are presented as μg/m 3 . We suggest notations be used consistently throughout the document. 36. Page 20 line 10: It is noted that EPA has found that air pollutant emissions that amount to 1.2 percent of the total inventory met the statutory te st for contribution.Summary of interagency working comments on draft rule under EO 12866.

These comments do not necessarily represent the views of OMB and are su bject to further policy review. How does this value compare to the value for lead in avgas? (What percent of Pb in avgas contributes to the total inventory of Pb?) 37. Page 29 line 12: It is noted that particles size influences the amount of time spent in [insert “the ”] aerosol phase. It should be noted as well this influences their residence time in the atmosphere. 38. Page 30 line 6: It is noted “Once deposited to surfaces, lead can subsequently be resuspended into the ambient air and, because of the persistence of lead, emissions of this metal contribute to environmental media concentrations for many years into the future”. It should be added that the emissions contribute to environmental media concentrations for many years into the future “as it is cycled within and between environmental media such as soil, air, and water”. 39. Page 31 line 6: Insert at the end of the paragraph “as described above”. 40. Page 48 top: Volume of avgas produced presented in gallons yet concentrations of Pb in avgas are presented in g/L . We suggest the gallon notation also be converted to liters here and present the concentrations in g/L as well as g/gal as noted in the equation in the next paragraph. 41. Page 51 last ¶: General aviation and air taxi acronyms are presented here but should be defined in the preceding paragraph where GA and TA are listed with no definition. 42. Page 53 last ¶: What is the concentration of Pb in 100 Octane in units of g/L so that one may compare to the 0.56 g/L presented for 100LL in the previous sentence? 43. Page 57 line 17: typo: “an” should be “and” 44. Page 62 last ¶: Particulate emissions from piston - engine aircraft are presented as 10,000 μg/m3 . It would be helpful to put this value in perspective with respect to ambient air TSP air quality standards (i.e ., for particles less than 2.5 micron in diameter, the 24 hour attainment standard is 35 μg/m 3 ). 45. Page 63 ¶2: “due to their “small” size”... We suggest an (i.e., typically less than one micron in diameter). 46. Page 71 ¶1: It is noted “We are requesting comm ent on the availability of additional monitoring or modeling studies that evaluate the air quality impact of lead emissions from piston - engine aircraft as well as potential impacts on soil, houseSummary of interagency working comments on draft rule under EO 12866.

These comments do not necessarily represent the views of OMB and are su bject to further policy review. dust, surface water or other environmental media”, we sugges t adding a request for comment on studies that will also assess potential impact on public health and welfare. 47. Page 86 top: There is a discussion of lead concentrations in fish. In an effort to put these numbers in perspective, fish advisory levels for lead in fish should be presented too.