Memorandum 

Subject: Contingency precursor effectiveness ratio using additional information 

To: File for docket EPA-R09-OAR-2013-0534, San Joaquin Valley action 

From: Scott Bohning, Environmental Engineer, Air Division, EPA Region 9 

Date: August 12, 2013 

On August 6, 2013, Karen Magliano of the Air Resources verbally relayed to me the total NOx 

and direct PM2.5 emissions used as input to the modeling used for the San Joaquin Valley 2008 

PM2.5 plan. They were 235.4 and 126.4 tons/day, respectively. These numbers provided 

documentation additional to that provided in the original plan submittal and in Appendix A to the 

Contingency Measure SIP, showing how ARB derived a precursor effectiveness equivalency 

ratio for NOx and direct PM2.5 emissions reductions. On August 8th, she also supplied 

additional significant figures to design value concentrations in the table describing the ratio 

calculation, shown in the attached e-mail. With this additional information, I was able to 

duplicate ARB’s 1:9 direct PM2.5 to NOx emission reduction ratio relied on for contingency in 

the SIP, as shown in the second attachment. 

Attachments 

“RE: attempt to duplicate PM/NOx ratio “,e-mail from Karen Magliano, ARB, 2013-08-08 

“Relative effectiveness of SJV precursor emission reductions” spreadsheet, Scott Bohning, EPA 

Region 9, 2013-08-08 
1

Bohning, Scott

From: Magliano, Karen@ARB [kmaglian@arb.ca.gov]

Sent: Tuesday, August 06, 2013 2:34 PM

To: Bohning, Scott

Subject: RE: attempt to duplicate PM/NOx ratio

Scott: 

Just left you a voice mail. Ajith used design values that had two significant figures. When you plug those into your table, 

the calculations match. Here are the values to use: 

2014 

DV 

10% PM2.5 10% NOx

Bakersfield- CA 14.28 13.58 14.13

Bakersfield -Planz 14.70 14.00 14.56

BakersfieldGolden 14.39 13.70 14.24

Let me know if you need any other information. 

Regards, Karen 

From: Bohning, Scott [mailto:Bohning.Scott@epa.gov] 

Sent: Tuesday, August 06, 2013 12:36 PM 

To: Magliano, Karen@ARB 

Subject: attempt to duplicate PM/NOx ratio 

Karen - 

Thank you for leaving phone message with PM2.5 and NOx SJV domain emissions totals, and thanks to Ajith for digging 

them out. 

Could you clarify whether the 126.4 tpd PM2.4 and 235.4 tpd NOx are for the 2005 base case, 2014 base case, or 2014 

controlled case? To get the ratio, 10% reductions were applied to post-control 2014 case, so the latter are what we 

chiefly need (though all three of these would be nice). 

Assuming these were for 2014 controlled case, I plugged them in an earlier attempt of mine to duplicate the relative 

precursor effectiveness ratio calculation (see attached, with calculation in columns “M”-“O”, to the right of “ARB Table 

1”), but I get ratios of 7 or 13, rather than 9. Perhaps I am not using the same procedure you folks did. Any idea what I 

am doing wrong here? 

Thanks... 

- Scott B. 

-- 

=+=+=+=+=+=+=+=+=+=+=+=+=+=+= 

"Scott Bohning" <bohning.scott@epa.gov> 

U.S. EPA Region 9, AIR-7 

415/947-4127 fax-3579 
Relative effectiveness of SJV precursor emission reductions sjb 2013-08-06 (prev. ver 2011-06-09)

 replication of ARB precursor effectiveness table

Effectiveness of precursor emission reductions

Table 1 from ARB's draft Precursor Effectiveness, 5/6/2011 ("Precursor Effectiveness.pdf")

 (last column is ratio of PM2.5 effect per ton of NOx reduction over that for direct PM2.5) Modeling domain emissions totals Attempt to duplicate 9:1 ratio

from Karen Magliano, ARB

ARB Table 1: The effectiveness of precursor controls on the 2014 design value personal communication, 2013-08-06 Using DV change from Table 1,

amended with values having two significant figures, e-mail from Karen Magliano, ARB, 2013-08-06 (assumed to refer to 2014 emissions) divide by 10% of emissions

Site Measured

2006 DV

(μg/m3)

Modeled

2014 DV

With Controls

(μg/m3)

Modeled

2014 DV

With Further 10% 

NOx Reduction

(μg/m3)

Modeled

2014 DV

With Further 10% 

PM2.5 Reduction

(μg/m3)

PM2.5 

Effectiveness 

Relative to NOx

NOx (tpd) PM2.5 

(tpd)

2014 DV 

change 

with 10% 

NOx 

reduction

2014 DV 

change 

with 10% 

PM2.5 

reduction

NOx 

effectiveness 

(μg/m3) / 

tpd

PM2.5 

effectiveness 

(μg/m3) / 

tpd

PM2.5/NO

x effectiveness ratio

Site 1 (BakersfieldCalifornia)

18.5 14.28 14.13 13.58 8.7 235.4 126.4 0.15 0.70 0.0064 0.0554 8.69

Site 2 (BakersfieldPlanz)

18.9 14.70 14.56 14.00 9.3 0.14 0.70 0.0059 0.0554 9.31

Site 3 (BakersfieldGolden)

18.6 14.39 14.24 13.70 8.6 0.15 0.69 0.0064 0.0546 8.57

average 8.9 8.86