### From: "Higgins To: Melanie King/RTP/USEPA/US@EPA

cc: RobertJ Wayland/RTP/USEPA/US@EPA, Peter Tsirigotis/RTP/USEPA/US@EPA

Date: Wednesday, February 17, 2010 01:00PM Subject: RICE -- edits History: This message has been replied to and forwarded.

Hi Melanie,

I've attached a pdf of suggested changes to the RIA -- the first is to try to address concerns about ground level transport and the characertization, the second clarifies some of the hazardous constituent language. Please let me know if you have concerns about either of these or if you can work them into the RIA.

Additionally, could you also consider the following: USDA still questions the assumption about the distribution of irrigation engines among major and area sources. Given the signature deadline, can you add some language to the source estimates memo, and possibly to the RIA, that states "For estimating the number engines located at major and area sources, we used our best engineering judgment, and we recognize that it may lead to an overestimate or underestimate of costs and benefits for certain sectors." Another suggestion is the following: " Given that few farms are known to be current major sources, less than 40% of the farms with RICE engines may be located at major sources, but EPA did not have available data to quantify an alternative estimate."

Finally, is the limited use category for area sources supposed to be for engines greater than 500 or 300? The regulatory language and preamble uses a 500 threshold, but retrofits are required for area source engines greater than 300, and, the costs of retrofits for 300 HP engines running less than 100 hours a year does not exceed the low end of the benefits
range.

Please give me a call if you have questions.

Regards, Cortney

Attachments:

CI RICE NESHAP RIA 2-17-10_p133.pdf CI RICE NESHAP RIA 2-17-10_p119.pdf 

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2/17/2010 htt p s://rtairmail1.rt p .e p a. g ov/mail/mkin g .nsf/ ( $Inbox ) /8465B14AC8C09A79718E0532B3

...7-4 The underlying emissions modeling and air quality modeling account for the current
distribution of emissions sources , including both urban and rural sources. In addition, the air quality modeling included 14 vertical layers to simulate the differences between ground-level emissions and higher stack emissions (U.S. EPA, 2006a). The distance that particles travel primarily depends on the si ze of the particle and meteorologi cal conditions, such as wind speed and precipitation. Fine particles can have an atmospheric half-life of days to weeks and travel hundreds to thousands of kilometers, whereas ultrafine and coarse particles travel less than ten kilometers (U.S. EPA, 2009c). Because we have not undertaken a study specific to emissions at ground level from RICE, with regard to transport issues and to size fraction of PM 2.5 emissions (e.g., ultrafines and near ultrafin es), there is uncertainty as to how far such emissions will travel and thus with regard to populations affected. Evidence from recent air quality modeling for mobile source rules with similar engines (U.S. EPA, 1999; U.S. EPA, 2000; U.S. EPA, 2004; U.S. EPA, 2008e; U.S. EPA, 2010c) shows that so me fine particles can travel long distances in the atmosphere, but the proportion of such emissi ons from RICE that travel more than short
distances under typical ground level meteorological conditions is not yet definitively known
, thus introducing a potentially important source of uncertainty

.
The benefit-per-ton coefficients in this analysis were derived using modified versions of the health impact functions used in the PM NAAQS Regulatory Impact Analysis (U.S. EPA, 2006b). Specifically, this analysis uses the benef it-per-ton method first applied in the Portland Cement NESHAP RIA (U.S. EPA, 2009a), which incorporated three updates: a new population dataset, an expanded geographic scope of the benefit-per-ton calculation, and the functions directly from the epidemiology studies with out an adjustment for an assumed threshold. 3 Removing the threshold assumption is a key difference between the method used in this analysis
of PM co-benefits and the methods used in RIAs prior to that for the Portland Cement NESHAP,
and we now calculate incremental co-b enefits down to the lowest modeled PM 2.5 air quality
levels.

EPA strives to use the best available science to support our benefits analyses, and we recognize that interpretation of the science regarding air pollution and health is dynamic and evolving. Based on our review of the body of scientific literature, EPA applied the no-threshold model in this analysis. EPA’s Integrated Science Assessment for Particulate Matter (U.S. EPA, 2009c), which was recently reviewed by EPA’s Clean Air Scientific Advisory Committee (U.S. EPA-SAB, 2009a; U.S. EPA-SAB, 2009b), concluded that the scientific literature consistently

3 The benefit-per-ton estimates have also been updated si nce the Cement RIA to incorporate a revised VSL, as discussed on the next page.7-18 strong respiratory irritants such as acrolein.

Other Air Toxics

In addition to the compounds described above, other compounds in gaseous hydrocarbon and PM emissions from RICE engines would be aff ected by this rule. Information regarding the health effects of these compounds can be found in EPA’s IRIS database. 59

The distance that these HAPs travel away from the emission source depends on several factors. HAPs such as formaldehyde, acetaldehy de, PAHs, and acrolein are emitted as gases. Regional photochemical model simulations , examining particular scenarios, have shown that gaseous HAPs like formaldehyde and acetaldehyde can be transported hundreds of kilometers from their emissions source in distinct plumes (U.S. EPA, 2010b). Further, these emissions can contribute to regional airmasses with elevated co ncentrations of gaseous HAPs. These polluted
airmasses , under the scenarios examined, can be transported thousands of kilometers and affect locations well distant from the original emissions source. Some gaseous HAPs with higher molecular weight, such as toluene, can tr ansform into particles in the atmosphere. For engines examined in this rule, EPA does not have enough information to determine how far each of the
HAPs will travel. For In general, for HAPs emitted as particles, such as metals, the travel distance primarily depends on the size of the pa rticle and meteorological conditions, such as wind speed and precipitation. Fine particles can have an atmospheric half-life of days to weeks and travel hundreds to thousands of kilometers, whereas ultrafine and coarse particles travel less
than ten kilometers (U.S. EPA, 2009c). The level at which the emissions occur can also play a role in determining transport di stances. For instance, ground level emissions are less likely to travel long distances when compared to particles emitted substantially above ground level.

Carbon monoxide co-benefits

Carbon monoxide (CO) exposure is associated with a variety of health effects. Without knowing the location of the emission reductions and the resulting ambient concentrations using fine-scale air quality modeling, we were unable to estimate the exposure to CO for nearby populations. Due to data limitations, we were unabl e to estimate the benefits associated with the 14,000 tons reductions in CO emissions that would occur as a result of this rule.

Carbon monoxide in ambient air is formed primarily by the incomplete combustion of carbon-containing fuels and photochemical reac tions in the atmosphere. The amount of CO

59 U.S. EPA Integrated Risk Information System (I RIS) database is available at: www.epa.gov/iris