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 the following questions, to help EPA
collect useful information on how regulation of avgas may cause
commercial disruptions:

How many companies manufacture 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? 

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.

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?  

Page 17 line 8:  It is mentioned that EPA has discussed it
“endangerment finding” authority at length in recent notices.  It
should be noted here that these endangerment findings are with respect
to green house gases and not lead.

Page 17 line 18:  Concentrations of the standard are presented in text
unites of micrograms per cubic meter but in previous and future text
units are presented as µg/m3.  We suggest notations be used
consistently throughout the document.

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 test for contribution.  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?)

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.  

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”.  

Page 31 line 6:  Insert at the end of the paragraph “as described
above”.

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.

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.

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?  

 

Page 57 line 17: typo: “an” should be “and”

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/m3).

Page 63 ¶2:  “due to their “small” size”… We suggest an
(i.e., typically less than one micron in diameter).

Page 71 ¶1:  It is noted “We are requesting comment 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, house dust, surface water or other
environmental media”, we suggest adding a request for comment on
studies that will also assess potential impact on public health and
welfare.

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.

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

These comments do not necessarily represent the views of OMB and are
subject to further policy review.

