Department of Pesticide Regulation

Mary-Ann Warmerdam M E M O R A N D U M Arnold Schwarzenegger Director Governor 

TO: John S. Sanders, Ph.D., Chief 

Environmental Monitoring Branch 

FROM: Terrell Barry, Ph.D., Research Scientist III Original signed by 

Frank C. Spurlock, Ph.D., Research Scientist III Original signed by 

Randy Segawa, Environmental Program Manager I Original signed by

 Environmental Monitoring Branch 

(916) 324-4137 

DATE: September 29, 2007 

SUBJECT: PESTICIDE VOLATILE ORGANIC COMPOUND EMISSION ADJUSTMENTS 

FOR FIELD CONDITIONS AND ESTIMATED VOLATILE ORGANIC 

COMPOUND REDUCTIONS–REVISED ESTIMATES 

I. Summary 

The purpose of this memorandum is to develop refined emission adjustment factors to account 

for the effect of application method on volatile organic compound (VOC) emissions from 

pesticides, with particular emphasis on fumigants, and to estimate the VOC reductions associated 

with changes to fumigant application methods. Each year, the Department of Pesticide 

Regulation (DPR) updates an inventory of pesticide VOC emissions for May–October for 

specified areas and compares the emissions on a relative basis to 1990 or 1991 as the base year. 

Prior to 2007, DPR assumed 100% of applied fumigants volatilize to the air. Field monitoring 

data shows that fumigant emissions are less than 100% and vary with application method. 

There are several dozen field studies that measured fumigant emissions. Emissions vary from 

9 to 100% of the amount applied, depending on the fumigant and application method. However, 

data is not available for all application methods in current use or in use during the 1990/91 base 

year. When no data is available, emissions have been estimated with surrogate data. In addition 

to emission estimates associated with each application method, DPR has estimated the frequency 

with which the various application methods were used during 1990/91 base year, as well as 

currently. Registrant data and pesticide use reports (PURs) were used for these estimates. 

DPR used the emissions for each application method, and the frequency with which the various 

application methods are used to adjust its VOC emission inventory, as well as to estimate the 

possible emission reductions that would result from further changes to application methods. This 

analysis shows that application method changes between 1990/91 and 2004 are insufficient to 

achieve the required VOC reductions in at least one of the targeted areas. While application 

method changes since 1990/91 have lowered emission rates, increased fumigant use more 

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John S. Sanders, Ph.D. 

September 29, 2007 

Page 2 

than offsets the application method reductions. Moreover, even if all fumigant applications used 

“low-emission” methods, the VOC reductions would be insufficient to achieve the required 

levels in at least one area. Limits on fumigant VOC emissions may be needed during 

May–October to ensure the required VOC reductions are achieved. 

DPR published its initial estimates of emissions in a memorandum dated April 6, 2007. This 

memorandum updates and revises those initial estimates based on recently submitted data, and 

comments (both public and scientific peer review) on the April 6 memorandum. 

II. Background 

Pesticide VOCs can contribute to the formation of ground-level ozone, which when present in 

high concentrations is harmful to human health and vegetation. The federal Clean Air Act 

requires each state to submit a state implementation plan (SIP) for achieving and maintaining 

federal ambient air quality standards, including the ozone standard. In 1994, California’s Air 

Resources Board and DPR developed a SIP element to track and reduce pesticidal sources of 

VOCs in five regions that do not meet the 1-hour ozone standard (ozone nonattainment areas): 

Sacramento Metro, San Joaquin Valley, Southeast Desert, Ventura, and South Coast. On 

February 21, 2006, the U.S. District Court (Eastern District of California) ordered DPR to 

implement regulations by January 1, 2008, to achieve the VOC emission reduction goals. DPR 

regulation 07-002 complies with this order. 

In accordance with the 1994 SIP, DPR developed a method to track pesticide VOC emissions 

(VOC emission inventory). Each year, DPR estimates pesticide VOC emissions for 

May–October in each nonattainment area and compares the emissions on a relative basis to 

1990 or 1991 as the base year. DPR initiated major revisions to the pesticide VOC emission 

procedures in 2002 (Spurlock, 2002a). Numerous updates and improvements to the VOC 

inventory calculation procedures have been made since that time (Spurlock, 2002b, 2004, 2005, 

2006; Roush, 2006). The revisions have improved the accuracy of DPR’s VOC inventory 

relative to earlier versions (e.g., Spurlock, 2002c). 

Prior to 2007, the potential emission for a pesticide application was calculated as: 

VOC emission (pounds) = pounds pesticide product applied x emission potential (EP) 

where EP is the EP of the pesticide product. EP is a measure of the VOC content of a product. 

However, additional factors beyond product composition affect emissions under actual use 

conditions. In recognition of this, the 1994 pesticide element of California’s SIP contains a 

provision for incorporating new knowledge into pesticide VOC emissions estimation procedures. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 3 

“The 1990 baseline year and subsequent year estimates may be further adjusted by additional 

VOC Emission Factors if additional information becomes available regarding the reactivity of 

compounds, the impact of temperature, moisture, deposition substrate, method of application, 

and other factors. Any additional VOC Emission Factor(s) will be pesticide product specific.” 

(DPR, 1994).1 

Fumigants are among the highest VOC contributors due to both their high levels of use and 

their high-EPs. For the fumigants 1,3-dichloropropene (1,3-D), chloropicrin, and methyl 

bromide EPs of 100% are assumed. Thus, the VOC estimation procedures assumed that all 

of these applied fumigants are eventually released to the troposphere. In the case of 

metam-sodium and N-methyl dithiocarbamate (metam-potassium) products, EPs assume 

100% conversion to methyl isothiocyanate (MITC) followed by eventual release of 100% 

of MITC to the air. Similarly, for products containing sodium tetrathiocarbonate, EPs assume 

100% conversion to carbon disulfide followed by release of 100% of carbon disulfide to the 

air. DPR has conducted numerous fumigant field monitoring studies over the last 15 years 

(e.g. <http://www.cdpr.ca.gov/docs/dprdocs/methbrom/pubs.htm>). Other researchers have 

also published fumigant field study results in peer-reviewed literature. Those studies 

demonstrate that the assumption of 100% fumigant emission to the air is inaccurate in most 

cases. This memorandum describes development of emission adjustment factors accounting 

for the effect of application method on VOC emissions from pesticides, with particular 

emphasis on fumigants. Using application method adjustment factors, the potential emission 

for a pesticide application is calculated as: 

VOC emission (pounds) = 

pounds product applied x EP x application method adjustment factor 

The fumigant application method adjustment factors developed here are expressed as a 

proportion of the amount of applied fumigant that is emitted to the air. The adjustment factors 

are application method- and fumigant-specific, based on measured data, and yield more refined 

estimates of fumigant VOC emissions than previous assumptions. Section III describes the 

available emission data and development of the application method adjustment factors. DPR 

regulation 07-002 refers to the application method adjustment factor as an “emission rating.” 

In California, all agricultural and commercial pesticide applications must be reported. The 

county agricultural commissioners and DPR compile these PURs into a database. DPR uses 

pounds of product applied recorded in this database to calculate the VOC emissions for each 

pesticide application included in the pesticide VOC emission inventory, as shown in the 

equations above. Specific application methods are not recorded on PURs. Therefore, a second 

1

 On February 21, 2006, the U.S.- District Court (Eastern District of California) ordered DPR to use the 1991 

inventory as a surrogate for the 1990 baseline year. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 4 

adjustment is needed to account for the use of each fumigant application method. Section IV 

describes the pounds of product applied associated with each fumigant application method 

(method use fraction). DPR regulation 07-002 contains provisions to include method of 

application for field fumigations in the PURs, so the procedure outlined in Section IV will not be 

used in the future. 

Without the application method adjustment factors, fumigants account for more than 50, 80, and 

90% of the pesticide VOC emissions in the San Joaquin Valley, Southeast Desert, and Ventura 

nonattainment areas, respectively. Moreover, these are the 3 nonattainment areas where DPR 

does not currently achieve the 20% pesticide VOC reduction of the 1991 base year required by 

the U.S. District Court order. DPR is considering two regulation strategies to achieve pesticide 

VOC reductions from fumigants, particularly in the nonattainment areas. One strategy is to 

require use of “low-emission” fumigant application methods and/or prohibit certain “highemission” fumigant application methods. A second strategy is to establish limits on VOC 

emissions from fumigants within the nonattainment areas. Regulations that incorporate one or 

both of these strategies will be effective in 2008. Section V assesses these regulatory strategies 

by: (1) estimating the pesticide VOC emissions for the 1990/91 base year for each nonattainment 

area, with the application method and method use fraction adjustment factors; (2) estimating the 

VOC reductions that would have occurred if low-emission fumigant application methods had 

been used in 2004 for each nonattainment area; and (3) estimating the limit on fumigant 

emissions in each nonattainment area that would achieve the VOC emission reductions required. 

III. Estimates of Volatile Organic Compound Emissions Under Field Conditions 

(Application Method Adjustment Factors) 

In this context, an application method adjustment factor (emission rating in DPR regulation 

07-002) is the emissions of fumigant to the air under field conditions, expressed as a proportion 

(percentage) of applied fumigant, and is fumigant- as well as application method-specific. 

Fumigant emissions have been measured with several methods, both in the laboratory and in the 

field. Fumigant emission under field conditions is a complex process that likely varies with 

method of application, soil characteristics (e.g., particle size, moisture, organic content), weather 

conditions, and other factors. Due to this complexity, laboratory measurements may not provide 

an accurate estimate of fumigant emissions under field conditions. Therefore, DPR relies almost 

exclusively on field measurements to estimate emissions. Additionally, DPR prescribes many of 

the application procedures and equipment used for the monitoring studies as regulatory 

requirements. For example, DPR prescribes requirements for maximum application rate, 

application depth, tarpaulin type, soil moisture, and other critical parameters based on 

application equipment, procedures, and conditions of the monitoring studies. These parameters 

are summarized here, and full descriptions are provided in the original study reports. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 5 

The reason DPR has not incorporated application method adjustment factors previously is the 

need to estimate emissions using a consistent process for the 1990/91 base year as well as 

currently. Due to exposure concerns, fumigant application methods changed substantially 

beginning in 1993, and very few field studies have measured fumigant emissions associated with 

application methods prior to this date. This section summarizes the available emission data and 

the assumptions used to estimate emissions for methods that have no data. 

A. Methyl Bromide 

DPR proposes application method adjustment factors for three main groups of methyl bromide 

field application methods: methods that use tractor shanks to inject methyl bromide into 

pre-formed beds and are covered with a tarpaulin, methods that use tractor shanks to inject 

methyl bromide into flat fields (broadcast) and are covered with a tarpaulin, and methods that 

use tractor shanks to inject methyl bromide into flat fields (broadcast) without a tarpaulin. In 

addition, there are some nonfield application methods. This approach is consistent with DPR’s 

current regulations for methyl bromide. 

1. Methyl Bromide Emission Studies 

DPR’s data set includes 30 field studies utilizing current application methods (Table 1). DPR’s 

analysis of these data shows that the nine bed fumigations monitored had very high 24-hour 

emissions (average of 81% of amount applied, coefficient of variation [CV] 38%). The 

13 broadcast applications with a tarpaulin show peak 24-hour emissions that average 24% of 

the amount applied (CV 52%). Broadcast applications without a tarpaulin show peak 24-hour 

emissions that average 37% of the amount applied (CV 47%). Methyl bromide is injected at 

different depths below the soil surface depending on the crop, with 6–12 inches classified as 

shallow injection, and 18–30 inches classified as deep injection. Analysis of the data 

(Barry 1999) shows that depth of application had no significant effect on the highest 24-hour 

emissions. While in concept there should be a depth effect, it is likely in practice that 

application-to-application variability is too large to detect that effect. 

Table 1 classifies methyl bromide application methods by the type of tractor configurations and 

includes bed/broadcast, tarpaulin type, chisel type, and injection depth. As required by California 

regulations since 2000, bed applications refer to fumigation of pre-formed beds, and broadcast 

refers to fumigation of flat fields. When a tarpaulin is used, it must be a “high barrier” tarpaulin 

that has a permeability between 5 and 8 milliliters methyl bromide per hour, per square meter, 

per 1,000 parts per million of methyl bromide under the tarpaulin at 30 degrees Celsius. In most 

cases, the tarpaulins are applied simultaneously with the fumigant and are buried under minimum 

amounts of soil. Chisel type refers to the type of tractor shank or knife used to inject methyl 

bromide beneath the soil surface. Most chisels are scythe-shaped, and curved forward or 

rearward relative to the direction of travel of the tractor. A “Nobel plow” chisel refers to 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 6 

horizontal v-shaped blades mounted by a vertical arm to the tool bar. Injection depth refers to 

depth from the soil surface of a flat field, or the top of the bed for a bed application. 

Five journal articles contained methyl bromide data most appropriate for developing application 

method adjustment factors: Majewski et al. (1995), Gan et al. (1996), Yates et al. (1996a), 

Yates et al. (1996b), and Gan et al. (1997). These articles report either direct flux (emission) 

measurements (e.g., aerodynamic method) in the field or measured soil column results. Table 2 

summarizes these studies and shows emission estimates for Broadcast Tarp and Broadcast 

Nontarp methods. Shallow and deep injections are pooled within these two categories due to the 

lack of significant difference associated with injection depth observed in the DPR data set. The 

average emission for Broadcast Tarp application method in these studies is 40%. The average 

emission for Broadcast Nontarp application method in these studies is 66%. 

2. Methyl Bromide Application Method Adjustment Factors 

The average peak 24-hour emissions for the three groups are used as the basis for DPR 

application method adjustment factors. Majewski et al. (1995) conclude that about 50% of the 

total emissions occur in the first 24 hours for applications. Therefore, the 24-hour emissions from 

the DPR data set can reasonably be doubled to provide an estimate of the application method 

adjustment factors. The application method adjustment factor for methyl bromide broadcast 

applications with a tarpaulin is 48% (both shallow and deep injection). The application method 

adjustment factor for methyl bromide broadcast applications without a tarpaulin is 74% (both 

shallow and deep injection). Due to the high 24-hour emissions for bed applications with a 

tarpaulin, 100% loss should be assumed. Of the two field studies described in the journal articles, 

Majewski et al. (1995) was a joint study with DPR, and its results are accounted for in DPR’s 

emission estimates shown in Table 1. The emissions measured in the remaining field study 

(Yates et al. 1996b) were consistent with the 13 DPR and registrant studies of that same 

application method that are used for the current methyl bromide regulations (Table 1). This last 

study has not been included in the determination of the application method adjustment factors 

because it has a negligible effect when grouped with 13 other studies, and to maintain 

consistency between the application method adjustment factors and current methyl bromide 

regulations. 

The data described support application method adjustment factors for current fumigation 

methods. Methods in use during 1990/91 were significantly different, particularly in the types of 

tarpaulins that were used. Low-density polyethylene tarpaulins (those that have greater 

permeability than the “high barrier” tarpaulins described above) were commonly used in 

1990/91. No field data for applications with low-density tarpaulin is available. However, 

laboratory data shows that these are more permeable than the tarpaulins currently used. Due to 

the lack of data, the application method adjustment factor for methyl bromide methods used in 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 7 

the 1990/91 base year are assumed to have the same emissions as current methods without a 

tarpaulin (74%). This assumption accounts for the permeable low-density tarpaulins that were in 

use at the time. 

In 1990/91 as well as currently, methyl bromide has uses as a space fumigant for both structures 

and harvested commodities. Methyl bromide emissions from these application methods are 

assumed to be 100% of the amount applied. 

The methyl bromide registrants submitted proposed application method adjustment factors to 

DPR (Stangellhini 2006a; Appendix 1), based on the Gan et al. (1997) study. Some of the 

registrants’ adjustment factors are similar to those proposed by DPR. However, several are 

inconsistent with DPR’s analysis of the available data (Appendix 2). 

Based on the emission data shown in Table 1 and the assumptions discussed above, the 

application method adjustment factors for methyl bromide are: 

Shallow injection w/ high permeability tarp or no tarp-broadcast 74% 

Shallow injection w/ low permeability tarp-broadcast 48% 

Shallow injection w/ high permeability tarp or no tarp-bed 100% 

Shallow injection w/ low permeability tarp-bed 100% 

Deep injection w/ high permeability tarp or no tarp-broadcast 74% 

Deep injection w/ low permeability tarp-broadcast 48% 

Nonfield soil (structural/post-harvest) 100% 

B. 1,3-Dichloropropene 

DPR proposes application method adjustment factors for four 1,3-D field application methods: 

methods that use tractor shanks to inject 1,3-D at shallow depths, methods that use tractor shanks 

to inject 1,3-D at deep depths, methods that include post-fumigation water treatments for shallow 

injection, and chemigation with drip irrigation systems. 

1. 1,3-Dichloropropene Emission Studies 

Appendix 3 is a revised analysis of six 1,3-D field monitoring studies. Four studies employed a 

shank injection at varying depths and two studies employed drip application. In contrast to 

methyl bromide, 1,3-D studies appear to show differing emissions with depth of injection, but 

standard high-density tarpaulins have little or no effect on 1,3-D emissions (Yates et al. 2002). 

The four shank studies were grouped into deep (18 inches or deeper) and shallow (14 and 12 

inches) applications and simple averages taken of the emission percentage in each group. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 8 

Use of 1,3-D was suspended in early 1990 due to high ambient air concentrations monitored in 

Merced. In researching mitigation measures to reduce emissions, the registrant conducted a flux 

study using elevated soil moisture (Knuteson et al. 1992). This soil moisture mitigation measure 

is now a part of the shank application methodology. 

Gao and Trout (2007) used flux chambers to estimate emissions for several chloropicrin and 

1,3-D application methods, including high-density polyethylene tarpaulin, high-density 

polyethylene tarpaulin with pre-irrigation, single post-fumigation water treatment, multiple 

post-fumigation water treatments (intermittent watering-in), and virtually impermeable film. 

Those researchers reported problems maintaining a seal between the soil and the chamber. 

Consequently predictions of 1,3-D emission reductions due to post-fumigation water treatments 

are subject to considerable uncertainty because the Gao and Trout (2007) study is the only 

information available for 1,3-D on this mitigation measure. However, reductions observed in 

their study are qualitatively consistent with demonstrated reductions in MITC emissions for 

post-fumigation water treatments. 

2. 1,3-Dichloropropene Application Method Adjustment Factors 

Appendix 3 summarizes and estimates the 1,3-D emissions for the application methods currently 

used, based on the available field studies and the emission adjustments (application factors) 

described in DPR’s recommended conditions for 1,3-D restricted materials permits (DPR 2002). 

Field studies for 1,3-D have been conducted during the fall and spring seasons only. DPR’s 

recommended permit conditions (2002) include an ad hoc adjustment factor for 1,3-D 

applications during the summer. We have chosen not to include the summer adjustment factor 

for 1,3-D application methods in these VOC emission estimates for three reasons. One, the 

summer adjustment factors are ad hoc, and not based on any scientific data or evaluation. Two, 

DPR does not use a seasonal adjustment for its regulatory emission values for any of the other 

fumigant. Three, the revised method for estimating VOC emissions described here is based on 

assigning a single field adjustment factor for each application method and fumigant combination; 

a seasonal emission adjustment would greatly increase the complexity of the VOC calculations. 

DPR will assume that reductions in 1,3-D emissions for three post-fumigation water treatments 

are approximately one-third less than an untarped shallow injection application. The monitoring 

data for 1,3-D deep injections show peak emissions occurring several days later than other 

fumigants. The timing and effect of the post-fumigation water treatments for 1,3-D deep 

injections is uncertain, and the emissions have not been estimated. Other application methods 

that appear to reduce chloropicrin emissions, such as pre-irrigation and virtually impermeable 

film may be problematic due to labeling requirements and other factors (Gao and Trout, 2007). 

Therefore, these application methods are not recommended at this time. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 9 

In 1990/91 there were virtually no applications of 1,3-D during the ozone season so no 

application method adjustment factors are needed for methods in those years. 

Based on the emission data shown in Table 3 and the assumptions discussed above, the 

application method adjustment factors for the 1,3-D are: 

Shallow injection w/ high permeability tarp or no tarp-broadcast 65% 

Shallow injection w/ three water treatments 44% 

Deep injection w/ high permeability tarp or no tarp-broadcast 26% 

Drip w/ high permeability tarp or no tarp 29% 

C. Chloropicrin 

The majority of chloropicrin is applied as a mixture with either methyl bromide or 1,3-D; a few 

applications use chloropicrin as the sole fumigant. The same application methods that are used 

for methyl bromide or 1,3-D will be used for chloropicrin, but with different application method 

adjustment factors. 

1. Chloropicrin Emission Studies 

Chloropicrin registrants measured chloropicrin emissions from several field applications (Beard 

et al. 1996). This study provides adequate data to characterize chloropicrin emissions for most of 

the current application practices. Emissions measured in this study showed relative differences 

similar to methyl bromide, with lower emissions associated with tarped broadcast applications 

and higher emissions associated with untarped broadcast and bed applications (Table 4). 

However, the study did not measure emissions for deep injection application methods, so the 

effect of injection depth is unknown. Data presented by the chloropicrin registrants yield similar 

conclusions, except the two studies Gillis and Smith (2002) and Lee et al. (1994) are either not of 

sufficient quality or do not include sufficient data to judge the quality to support their use in the 

DPR estimation of the adjustment factors. Chloropicrin registrants also measured emissions 

associated with chemigation of chloropicrin through a drip irrigation system (Knuteson and 

Dolder, 2000; Rotonardo, 2004; van Wesenbeeck and Phillips, 2000). These studies provide 

adequate data for the emissions from the drip application method, and shows substantially lower 

emissions than injection methods (Table 4). Gao and Trout (2007) used flux chambers to 

estimate emissions for several chloropicrin and 1,3-D application methods, including highdensity polyethylene tarpaulin, high-density polyethylene tarpaulin with pre-irrigation, single 

post-application water treatment, multiple post-application water treatments (intermittent 

watering-in), and virtually impermeable film. Those researchers reported problems maintaining a 

seal between the soil and the chamber. Consequently, predictions of chloropicrin emissions 

associated with the intermittent watering-in application method are subject to considerable 

uncertainty because the Gao and Trout (2007) study is the only information available for 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 10 

chloropicrin on this mitigation measure. However, reductions observed in their results are 

qualitatively consistent with demonstrated reductions in MITC emissions for intermittent 

watering-in methods. 

2. Chloropicrin Application Method Adjustment Factors 

The Beard et al. (1996), Knuteson and Dolder (2000), Rotonardo (2004), and van Wesenbeeck 

and Phillips (2000) studies will be used to produce the DPR application method adjustment 

factors. The emissions from Beard et al. (1996) are shown in Table 4. Similar to the proposed 

methyl bromide factors (Barry, 2006), the proposed chloropicrin factors only distinguish 

between tarpaulin and no tarpaulin. No depth factor will be included. All broadcast tarpaulin 

method emission results will be combined to produce an average estimate. 

The chloropicrin data set is small, as a result it is impossible to reliably distinguish between 

emissions for bed and broadcast applications. Thus, no separate field adjustment factor for 

bed methods will be estimated. Instead, based on the known high-emission characteristics of 

methyl bromide bed applications (Barry, 1999), the chloropicrin emission estimates for bed will 

be combined with the no tarpaulin method. 

The drip application method is separated because the emissions appear to be substantially lower 

than the shank injection methods. 

As with methyl bromide, chloropicrin applications methods in 1990/91 used more permeable 

low-density polyethylene tarpaulins. Stangellhini (2006b, Appendix 1) proposes, and DPR 

agrees, that 1990/91 chloropicrin applications should be assigned the application method 

adjustment factor for applications without a tarpaulin. 

DPR will assume that reductions in chloropicrin emissions for intermittent watering-in consisting 

of three post-fumigation water treatments is approximately one-third less than an untarped 

application. Other application methods that appear to reduce chloropicrin emissions, such as 

pre-irrigation and virtually impermeable films may be problematic due to labeling requirements 

and other factors (Gao and Trout, 2007). Therefore, these application methods are not 

recommended at this time. 

Based on the emission data shown in Table 4 and the assumptions discussed above, the 

application method adjustment factors for chloropicrin are: 

Shallow injection w/ high permeability tarp or no tarp-broadcast 64% 

Shallow injection w/ low permeability tarp-broadcast 44% 

Shallow injection w/ high permeability tarp or no tarp-bed 64% 

Shallow injection w/ 3 water treatments 43% 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 11 

Shallow injection w/ low permeability tarp-bed 64% 

Deep injection w/ high permeability tarp or no tarp-broadcast 64% 

Deep injection w/ low permeability tarp-broadcast 44% 

Deep injection w/ 3 water treatments 43% 

 Drip w/high permeability tarp 12% 

 Drip w/low permeability tarp 12% 

C. Metam-sodium and Metam-potassium 

Metam-sodium and metam-potassium fumigant action and VOC emissions are due to the 

hydrolysis product MITC, which is generated when sufficient water is applied to either 

metam-sodium or metam-potassium. The two active ingredients display essentially identical 

chemical behavior. In the remainder of this document metam be used to collectively refer to both 

metam-sodium and metam-potassium. EPs for products containing these chemicals are expressed 

on an MITC equivalent basis (Spurlock, 2002a, 2005). Here emission factors are also derived on 

an MITC emission basis. 

DPR proposes application method adjustment factors for eight metam field application methods: 

Using tractor shanks to inject metam at shallow depths 

Chemigation through sprinkler irrigation systems 

Post-fumigation water treatments for both shank injection and sprinkler applications 

Spraying metam on the soil surface and incorporate using a rototiller 

Spraying metam on the soil surface and cover with additional soil (soil capping) 

Chemigation through flood irrigation systems 

Chemigation with drip irrigation systems 

1. Metam-Sodium Emission Studies 

The Metam-sodium Task Force submitted results from field studies conducted under their 

1997-2001 Field Program. The earliest studies monitored MITC air concentrations associated 

with standard sprinkler and standard shank injection applications (Merricks, 1999). Standard 

sprinkler and standard shank injection methods include water treatments immediately following 

completion of the application. Field study results were also submitted for shank injection and 

sprinkler applications employing new post-fumigation water treatments as mitigation measures 

aimed at suppressing MITC emissions (Merricks, 2001; Merricks, 2002). The post-fumigation 

water treatments consist of water applied immediately following the application but also 

additional water, usually at sunset of the first and second evenings following completion of an 

application. Emission profiles developed for all four of these application methods have been used 

previously by DPR to develop MITC buffer zones (Barry, 2006). 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 12 

DPR recently received a study characterizing a modified intermittent watering-in schedule 

(Sullivan et al., 2005). The modification eliminates the watering-in on the second night and alters 

the watering-in on the first night so that 2 rounds of half the sprinkler lines were run at a rate of 

0.2 inches/hour for 2 hours to apply a total of 0.4 inches over 4 hours. Thus, there are two 

watering-in sessions instead of three. This study has received an initial review and several data 

gaps were noted. At this time, DPR has not completely reviewed and found the study acceptable. 

However, this study included a 3-watering-in application done at the same time for 

comparison,.That three-watering-in application shows mass loss consistent with the Merricks 

(2002) study results. Therefore, it is likely the study will be found acceptable once the data gaps 

are addressed. 

DPR has three metam-sodium drip method and one rototiller method emission profiles developed 

using results from three field studies (Levine et al, 2005; Li et al., 2006; Wofford 2005). 

Table 5 shows the total MITC emissions over the 96-hour flux profiles for each of the 

application methods. The total MITC available for emission was calculated assuming a 

maximum, immediate conversion of metam-sodium to MITC of 95% (Wales, 2000) and 

adjusting for difference in molecular weight between metam-sodium and MITC. 

2. Metam Application Method Adjustment Factors 

The metam-sodium data set is small, as a result it is impossible to reliably distinguish between 

emission rates for sprinkler and shank injection methods. However, relative to the standard 

application methods, the emissions are substantially lower for post-fumigation water treatments 

of both sprinkler and shank injection. Thus, sprinkler and shank injection methods are combined 

but standard and post-fumigation water treatments are separated. The drip and rototiller 

application methods are separated because the emissions observed in Levine et al. (2005) and 

Wofford (2005) are substantially lower than observed for other application methods. 

Other application methods were commonly used in 1990/91 as well as currently, but the 

emissions have not been measured either in the laboratory or in the field. Specifically, no 

emission data is available for methods that consist of spraying metam on the soil surface and 

covering with additional soil (soil capping) or for methods that consist of chemigating using 

flood irrigation systems. In order to account for the emissions from these application methods in 

1990/91, DPR assumes that emissions from the soil capping method are the same as rototiller, 

and emissions from flood chemigation are the same as sprinkler. 

All of the metam studies and emissions described above were daylight applications. Unlike other 

fumigants, metam applications commonly have higher emissions at night compared to the day, 

particularly if applications occur at night. Wofford et al. (1994) measured emissions of nearly 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 13 

100% from a night sprinkler application. It is likely that other metam application methods also 

have higher emissions when done at night. Except for the standard sprinkler method, the 

emissions for metam night applications are unknown. The frequency of night applications is also 

unknown. Therefore, DPR does not currently account for the emission difference between day 

and night applications. 

Based on the emission data shown in Table 5 and the assumptions discussed above, the 

application method adjustment factors for metam (as a percentage of MITC) are: 

Shallow injection w/ high permeability tarp or no tarp-bed 77% 

Shallow injection w/ 3 water treatments 21% 

Shallow injection w/ 2 water treatments 28% 

Rotovate/rototill 14% 

Soil capping 14% 

Sprinkler 77% 

Sprinkler w/ 3 water treatments 21% 

Sprinkler w/ 2 water treatments 28% 

Flood 77% 

Drip w/ high permeability tarp or no tarp 9% 

Drip w/ low permeability tarp 9% 

D. Dazomet 

Similar to metam-sodium and metam-potassium, dazomet fumigant action and VOC emissions 

are due to the hydrolysis product MITC, which is generated when sufficient water is applied to 

dazomet. In addition to their chemical differences, dazomet is formulated as granules while 

metam-sodium and metam-potassium are formulated as liquids. The EP for dazomet is expressed 

on an MITC equivalent basis (Spurlock, 2002a, 2005). Here application method adjustment 

factors are also derived on an MITC emission basis. 

DPR proposes application method adjustment factors for two dazomet application methods: 

methods for which dazomet is applied to the soil surface followed by post-fumigation 

water treatments, and methods for which dazomet is incorporated into the soil followed by 

post-fumigation water treatments. 

1. Dazomet Emission Studies 

The data set for dazomet consists of three studies, two surface applied and one incorporated 

(Table 5). The registrants for a dazomet product submitted study results that included air 

concentrations and emission calculations for a surface and an incorporated application 

(Certis, 2004). There is significant uncertainty in the emission estimates for both the surface 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 14 

and the incorporated application methods due to the very calm wind conditions during the 

studies. Out of 18 sampling periods for each study only three sampling periods from the 

incorporated application and none of the sampling periods from the surface application resulted 

in statistically significant regressions used to estimate the emission rate. A third study conducted 

by DPR (Fan, in progress) monitored a surface application to small plots of dazomet. The 

regression analysis used to estimate emissions was statistically significant, but resulted in an 

emission calculation that was a factor of ten higher than the registrant studies. Because of the 

discrepancies in the emission estimates between the three studies, DPR and the registrant jointly 

initiated a fourth study. The analysis of the data from that study is in progress. Additionally, all 

of the available studies may underestimate VOC emissions from dazomet because of other VOCs 

formed by its degradation. The available studies only measured MITC, but other degradation 

products may also have significant VOC emissions (Subramanian, et al. 1996). 

2. Dazomet Application Method Adjustment Factors 

The available data set for dazomet is small and the emission factors vary by a factor of ten, so an 

average of the fraction of MITC emitted from all of the studies is used as the interim application 

method adjustment factor for all applications of dazomet products. DPR may revise this 

adjustment factor once the third and fourth studies are completed. DPR may also revise this 

adjustment factor after further evaluation of the other dazomet degradation products. The interim 

application method adjustment factor for all dazomet application methods is 17%. 

E. Sodium Tetrathiocarbonate 

Sodium tetrathiocarbonate fumigant action and VOC emissions are due to the hydrolysis 

product carbon disulfide, which is generated when sufficient water is applied to sodium 

tetrathiocarbonate. The EP for sodium tetrathiocarbonate is expressed on a carbon disulfide 

equivalent basis (Spurlock, 2002a, 2005). Here application method adjustment factors are also 

derived here on a carbon disulfide emission basis. 

DPR proposes application method adjustment factors for three sodium tetrathiocarbonate 

application methods: chemigation using drip irrigation systems, chemigation using 

mini-sprinkler systems, and flood/furrow chemigation. 

1. Sodium Tetrathiocarbonate Emission Studies 

Evaluations by DPR staff concluded that mini-sprinklers potentially result in higher off-site 

carbon disulfide air concentrations relative to the other application methods (Haskell, 1995). 

Thus, this method may also represent worst-case emissions of carbon disulfide. DPR has one 

direct flux (emission) study characterizing emissions of carbon disulfide following application of 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 15 

sodium tetrathiocarbonate by mini-sprinklers (Pilling, 1996). This study was the basis for buffer 

zones on the current labels. Emissions were characterized by the integrated horizontal flux 

method (Wilson and Shum, 1992) for 34.2 hours consisting of: (1) the application, (2) follow-up 

irrigation (watering-in), and (3) an additional 24 hours after completion of watering-in. The 

emission estimates indicate that 9.6% of the carbon disulfide generated by the sodium 

tetrathiocarbonate product was emitted during the 34.2 hours sampled. The emission profile 

shows the peak emissions occurred during the application process and then dropped rapidly 

to low emissions that were relatively uniform in value between 0.41 micrograms per square 

meter-second (ug/m2sec) and 1.02 ug/m2sec. However, on the morning of the second day 

emissions began to rise. At 0900 hours on the second day the emission estimate was 

1.23 ug/m2sec and the last 4-hour interval (mid-point time 1700 hours) showed an emission 

estimate of 2.6 ug/m2sec. The emission profile for the second night is unknown. Based 

upon emission profiles for standard shank and standard sprinkler application methods of 

metam-sodium, it is possible that without watering-in on the second night the emission of 

carbon disulfide would have continued to rise. Thus, the 9.6% estimate of total carbon disulfide 

emissions may underestimate the true total emissions. 

2. Sodium Tetrathiocarbonate Application Method Adjustment Factors 

We assume that the emissions from drip and flood/furrow chemigation are the same as 

mini-sprinkler. Based on the 9.6% emission rate measured in the study described above, the 

application method adjustment factors for sodium tetrathiocarbonate are: 

Drip 10% 

Sprinkler 10% 

Flood 10% 

F. Comments on the initial emission estimates and other fumigant emissions considerations 

DPR received numerous comments on its initial emission estimates contained in the April 6 

memorandum, but they had common themes. Several commentors disagreed with the studies that 

DPR relied on to estimate emissions. Some suggested that DPR should use additional published 

studies or studies unavailable to DPR to supplement the data used to estimate emissions. Some 

people commented that DPR used several unrepresentative studies to estimate emissions, or the 

data are insufficient to estimate emissions. DPR considered other studies prior to its initial 

estimates, and reconsidered them after receiving comments. In summary, the current set of 

studies used in this analysis is the database available. DPR staff has included in this analysis 

those studies that have been reviewed and accepted as sufficient quality to provide reliable 

results. The included studies were conducted at a variety of locations under a variety of 

meteorological conditions and over the entire year. The variety of locations, application methods, 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 16 

and meteorological conditions are varied in large part due to the diverse nature of agriculture in 

California. Appendix 4 contains a summary of the fumigant emission studies that it did not use 

and the reasons for excluding the data. 

DPR is relying on several dozen field studies to determine the emissions associated with the 

different application methods, and using surrogate field data where necessary. In some cases 

these field studies do not agree with laboratory studies. For example, multiple field studies show 

that depth of injection has no effect for methyl bromide applications, at least within the depth 

range studied (10-24 inches). Multiple field studies also show that normal tarpaulins have no 

effect on 1,3-D emissions. Multiple field studies show that bed fumigations have higher 

emissions than broadcast fumigations for methyl bromide. DPR believes that field studies 

provide a more accurate estimate of emissions than laboratory studies. Because of the 

discrepancies between laboratory and field studies, DPR intends to continue to rely on field 

studies to estimate emissions. 

No flux chamber estimates of emissions are used at this time because there are significant 

technical issues associated with flux chamber estimates including: (1) potentially significant 

effects on the local environmental conditions where the chambers are placed relative to the field 

as a whole. This effect may be largest for static chambers but may also affect dynamic chambers, 

(2) the sensitivity of dynamic chamber results to pressure gradients created by the air flow, and 

(3) the very limited coverage of the field by the sample chambers which can introduce a high 

degree of heterogeneity in the flux results (Reichman and Rolston, 2002; Majewski et al., 1995; 

Yates 2006). 

DPR has made several revisions to the 1,3-D emission estimates based on the comments 

received. In order to fully utilize the 4 studies, DPR originally combined them by linear 

interpolation to estimate the flux at 2 standard depths: 18 inches and 12 inches. DPR requested 

the peer reviewers to specifically evaluate this method for estimating emissions and other people 

commented on these estimates. Both peer reviewers found the linear interpolation approach 

reasonable. However, other people commented that DPR should group the studies by depth and 

use the average of each group to estimate emissions, consistent with the approach DPR used for 

the other fumigants. DPR agrees with these comments and has grouped the studies into deep (18 

inches or deeper) and shallow (14 and 12 inches) applications and simple averages taken of the 

emission percentage in each group. Several people commented that that the 3-water treatment 

regime for metam may be an ineffective method to reduce emissions from deep injections of 1,3­

D because the monitoring data shows later emissions associated with this application method. 

DPR agrees with the comment and has removed this method since the emissions cannot be 

reliably estimated. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 17 

Several people commented that DPR should apply other adjustment factors to the fumigant 

emission estimates. DPR considered other emission adjustments prior to its initial estimates, and 

reconsidered them after receiving comments. DPR believes there are insufficient data to further 

adjust emissions due to tarpaulin permeability (e.g., virtually impermeable films), temperature, 

soil type, or other factors. While it is likely that other factors influence fumigant emissions, the 

field-to-field variability is too high, and the data are insufficient to discern and quantify the effect 

of other factors. In addition, any adjustments need to be enforceable by field inspectors. 

Distinguishing soil type or other factors may be too difficult by observation or simple field tests. 

Several people commented that DPR should supplement its emission estimates with computer 

modeling, such as CHAIN_2D. DPR believes it is premature to use a first-principle model to 

estimate emissions. DPR may eventually use this or other models to supplement its emission 

estimates, but the current validation is insufficient and several input variables are difficult if not 

impossible to estimate. 

Some people commented that DPR should account for reactivity. In this context, reactivity refers 

to the ability of a specific chemical to create ozone. Carter and Malkina (2007) studied the 

reactivity of several pesticides and found that methyl bromide and MITC have relatively low 

reactivity, with maximum incremental reactivities of 0.03 and 0.35, respectively. Chloropicrin 

and 1,3-D have relatively high reactivity, with maximum incremental reactivities of 2.2 and 5.4, 

respectively. The maximum incremental reactivity is an estimate of the amount of ozone 

created, under a specified set of conditions. For example, one pound of methyl bromide will 

create 0.03 pounds of ozone under the specified conditions. DPR agrees that Carter’s study 

accurately estimates the reactivity of the fumigants. However, the fumigants are VOCs under 

federal law. See Title 40, Code Federal Regulations, § 51.100(s). Unless the U.S. Environmental 

Protection Agency amends part 51.100, DPR must include these fumigant emissions in the total 

VOC emission inventory. DPR cannot exclude either methyl bromide or MITC from the total 

pesticide VOC inventory based on their reactivity. DPR may, and would like to, consider the 

reactivity of various pesticides when designing VOC control measures, but must do so within the 

bounds of its requirement under federal law to obtain the necessary mass-based (as opposed to 

reactivity-based) reductions in VOC emissions. When the 1994 Pesticide Plan, that the court 

order enforces, was included in SIP, neither the State nor U.S. Environmental Protection Agency 

appreciated that a significant fraction of the VOC emission that the Plan would control do not 

appreciably contribute to ozone. Unless SIP is amended to account for this information, DPR has 

a limited ability to include such information in its regulatory decisions and still must meet its 

legal obligation. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 18 

G. Other pesticides 

Fumigants are the dominant contributors to pesticide VOCs, generally responsible for at least 

50–60% of emission in most California nonattainment areas. The next largest class of 

high-contributing pesticides is liquid formulations such as emulsifiable concentrates. In some 

cases, emissions calculated directly from the thermogravimetric analyses measurements without 

accounting for application method may over-estimate actual field emissions for some of these 

products. This may be especially true for products that are incorporated into the soil. In other 

cases, such as high solvent formulations that are foliar applied, it is unlikely that field processes 

reduce emissions significantly. In any event, there is little, if any data available that would allow 

estimation of application method adjustment factors for non-fumigant pesticides. Consequently, 

application method adjustment factors for non-fumigants are assumed to be 100% in all years. 

DPR may reconsider these non-fumigant field adjustment factors as further data becomes 

available. 

IV. Estimated Frequency of Use for Each Fumigant Application Method During 

May–October (Method Use Fractions) 

In California, all agricultural and commercial pesticide applications must be reported. County 

agricultural commissioners and DPR compile these PURs into a database. The PUR database 

includes the identity of the product applied, the amount applied, location, date, crop/site treated, 

and other information. DPR uses the pounds of product applied recorded in PUR database to 

calculate the VOC emissions for each pesticide application included in the pesticide VOC 

emission inventory. PUR database contains general information about the application method 

(i.e. air, ground, or other), but it does not indicate the specific application method. Therefore, 

another adjustment is needed to account for the use of each fumigant application method. DPR 

regulation 07-002 contains provisions to include method of application for field fumigations in 

PURs, so the procedure outlined here will not be used in the future. 

In general, different crops use different fumigant application methods. Roush (2006) found that 

the different nonattainment areas have different crops responsible for the majority of pesticide 

VOC emissions. Therefore, each nonattainment area should have a different set of adjustment 

factors to characterize the use of fumigant application methods. While the application method 

depends on the crop to be planted, other factors such as soil type, cost, and equipment 

availability also influence the choice of application method. For example, strawberries always 

use a shallow application method. However, the tarp broadcast and tarp bed application methods 

are both commonly used for strawberries, and these application methods have different 

emissions. Therefore, the type of crop is an unreliable surrogate to identify the fumigant 

application method in some cases. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 19 

DPR proposes to use a variety of methods to estimate the use of each of the fumigant application 

methods (method use fraction). The method for 1,3-D is the most accurate. As required under 

DPR’s 1,3-D management plan, the registrants maintain records of the specific application 

method for all 1,3-D applications. Johnson (2006) describes the May–October method use 

fractions, based on the registrants’ data. 

Lawson (2006) provides a survey of metam-sodium practices by several dozen growers and 

applicators in certain areas of the state. This survey includes a compilation of the application 

methods. The survey includes specific information for three nonattainment areas, as well as the 

top ten counties. DPR uses the percentage breakdown described in Lawson (2006) on the use of 

the various metam-sodium applications for the San Joaquin Valley, Southeast Desert, and 

Ventura nonattainment areas. DPR uses the breakdown for the top ten counties described in 

Lawson (2006) as a surrogate for the Sacramento Metro nonattainment area, and Ventura as a 

surrogate for the South Coast nonattainment area. 

Similar to the approach described by Stangellhini (2006a, 2006b; Appendix 1), DPR 

uses information from the PURs to estimate the May–October method use fractions for 

methyl bromide and chloropicrin based on the following assumptions: 

• For 1990/91 methyl bromide and chloropicrin applications, one-half of all strawberry, row, 

vegetable, and nursery crops were fumigated using a shallow injection broadcast method 

with a high permeability tarpaulin or no tarpaulin, and one-half were conducted with a 

shallow injection bed method and a high permeability tarpaulin. 

• For 1990/91 methyl bromide and chloropicrin applications, all tree and vine crops were 

fumigated using a deep injection method with a high permeability tarpaulin or no tarpaulin. 

• For 2004 methyl bromide applications, all row, vegetable, and nursery crops (except 

strawberries) were fumigated using a shallow injection broadcast method with a low 

permeability tarpaulin. 

• For 2004 methyl bromide applications, one-half of the strawberry applications were 

conducted with a shallow injection broadcast method and a low permeability tarpaulin, and 

one-half of the strawberry applications were conducted with a shallow injection bed method 

and a low permeability tarpaulin. 

• For 2004 methyl bromide applications, all tree and vine crops were fumigated using a deep 

injection method with a low permeability tarpaulin. 

• For 2004 chloropicrin applications, all row, vegetable, and nursery crops (except strawberries 

and Inline® applications) were fumigated using a shallow injection broadcast method with a 

low permeability tarpaulin. Inline® applications were conducted with a drip chemigation 

method. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 20 

• For 2004 chloropicrin applications, strawberry Inline product applications were conducted 

with a drip chemigation method. For the remaining strawberry applications, one-half were 

conducted with a shallow injection broadcast method and a low permeability tarpaulin, and 

one-half were conducted with a shallow injection bed method and a low permeability 

tarpaulin. 

• For 2004 chloropicrin applications, all tree and vine crops were fumigated using a deep 

injection method with a low permeability tarpaulin. 

NOTE: 2004 is the most recent year for which DPR has calculated a VOC emission inventory. 

The method use fractions for dazomet have no effect on the total emission estimates because the 

application method adjustment factor is 17% for both application methods. Similarly, the method 

use fractions for sodium tetrathiocarbonate have no effect on the total emission estimates 

because the application method adjustment factor for all three application methods is 10%. 

The information from the 1,3-D registrants, Lawson (2006), and PURs is adequate for estimating 

the method use fractions during the 1990/91 base year and currently. Tables 6–10 show the 

method use fractions during the 1990/91 base year in each nonattainment area. Tables 11–15 

show the method use fractions for 2004 in each nonattainment area. Tables 16–20 show the 

predicted method use fractions if all applications switched to a “low-emission” method for each 

nonattainment area. This last set of method use fractions was predicted by assuming that all 

“high-emission” methods switch to the most similar “low-emission” method. For example, 

Table 11 shows that 33% of the chloropicrin applications were conducted using shallow 

injection, tarped, bed (high-emission) method in the Sacramento Metro area during 2004. As 

shown in Table 16, DPR predicts that applicators using this method change to the shallow 

injection, tarped, broadcast method (low-emission) method to reduce emissions. 

The methyl bromide and chloropicrin registrants commented that the April 6 memorandum 

contained errors in some of the method use fractions. Based on these comments and follow-up 

information (Wilhelm, 2007), DPR has revised its methyl bromide and chloropicrin method use 

fractions for the 1990/91 base years for row, vegetables, and nursery crops. These changes 

slightly increase the base year due to the more frequent use of higher emission methods. Other 

suggested changes to the method use fractions were not incorporated due to the extensive 

recalculations the changes would require, and the changes involve revisions to the 2004 

emissions, which have minimal regulatory impact. 

Several commentors objected to the use of the undocumented method use fractions for metam. 

DPR does not normally use undocumented data. However, in this case the registrants’ 

information and professional judgment are likely more reliable than DPR’s, and DPR has 

employed the suggested method use fractions. At DPR’s request, the registrants have agreed to 

provide documentation on the method use fractions. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 21 

V. Estimated Effect of Fumigant Application Method Adjustments on the Volatile Organic 

Compound Inventory 

Previously, DPR did not include application method adjustment factors and method use fractions 

as part of its pesticide VOC emission calculations. Historically, DPR assumed all application 

method adjustment factors were 100%, and that fumigant use is equivalent to fumigant VOC 

emission. Table 21 summarizes the May–October emission inventory (assuming 100% fumigant 

VOC emissions) for 1990, 1991, and 2004 in each nonattainment area, and shows an overall 

increase in fumigant use and emissions for most nonattainment areas. 

This memorandum derives various fumigant- and application method-specific adjustment factors 

to refine the accuracy of the VOC inventory. Table 22 summarizes the application method 

adjustment factors associated with each fumigant and application method combination, and 

shows that most current application methods have lower emissions than methods used in 

1990/91. 

Tables 6–20 summarize the May–October method use fractions during 1990/91, 2004, and the 

predicted method use fractions if all applications switched to a “low-emission” method for the 

2008 regulations. The predicted method use fractions under the proposed regulations were 

determined using DPR’s best professional judgment and the application methods used during 

2004. 

Estimated pesticide VOC emissions for May–October that account for fumigant application 

methods are calculated by multiplying the unadjusted VOC emissions shown in Table 21, by the 

application method adjustment factors shown in Table 22 and the corresponding method use 

fractions in Tables 6–20. Table 23 shows the results of these calculations and provides estimates 

of the adjusted VOC emissions during the 1990/91 base year and 2004. Table 23 indicates that 

application method changes between 1990/91 and 2004 are insufficient to achieve the required 

VOC reductions in the San Joaquin Valley, Southeast Desert, and Ventura nonattainment areas. 

While application method changes since 1990/91 have lowered emission rates, increased 

fumigant use more than offsets the application method reductions. 

Table 23 also includes an estimate of the lowest pesticide VOC emissions currently feasible 

through changes in fumigant application methods. This was estimated by assuming that all 

field fumigations in 2004 used “low-emission” methods. Table 23 shows that even if all 

fumigant applications used “low-emission” methods, the VOC reductions will be insufficient 

to meet SIP obligations for Ventura and possibly insufficient for San Joaquin Valley and 

Southeast Desert. If future fumigant use decreases relative to 2004, the San Joaquin Valley and 

Southeast Desert nonattainment areas will likely achieve the required VOC reductions by 

switching to “low-emission” methods. Conversely, if future fumigant use increases, these two 

areas are unlikely to achieve the required VOC reductions by relying solely on changing to 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 22 

“low-emission” methods. The Ventura nonattainment area will likely require a substantial 

decrease in use during May–October in order to achieve the required VOC reduction, even if all 

applications changed to “low-emission” methods. 

Limits on fumigant emissions during May–October within each nonattainment area could 

achieve the required VOC reductions. Table 24 shows the maximum fumigant emissions that 

would achieve the required reductions, assuming VOC emissions from nonfumigant pesticides 

remain the same as 2004. If there are also no changes to the 2004 fumigation practices (i.e. no 

low-emission methods are adopted), acres fumigated and/or application rates during the 

May–October period would need to decrease approximately 20–50% in the San Joaquin Valley, 

Southeast Desert, and Ventura nonattainment areas in order to achieve the required VOC 

reductions (Table 24). The Sacramento Metro and South Coast nonattainment areas easily 

achieve the required reductions with current practices. It is likely that some combination of 

application method changes and emission limits is necessary to achieve the required VOC 

reductions for several nonattainment areas. 

cc: Paul H. Gosselin, DPR Chief Deputy Director 

Polly Frenkel, DPR Chief Counsel 

Tobi L Jones, Ph.D., DPR Assistant Director 

Jerome R. Campbell, DPR Assistant Director 

Sue Edmiston, DPR Branch Chief 

Linda Irokawa-Otani, DPR Staff Services Manager I 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 23 

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Industry Lane, Fredrick, Maryland 21704-7293. January 10, 2002. 

Pilling, R.L. 1996. Carbon disulfide flux from low volume emitter application of ENZONE®. 

Study AA19 sponsored by Entek Corporation, Brea, California 92821. DPR registration library. 

Volume 51031-093. 

Reichman, R. and D.E. Rolston. 2002. Design and performance of a dynamic gas flux chamber. 

J. Environ. Qual. Vol 31:1774-1781. 

Rotondaro, A. 2004. Monitoring of chloropicrin emissions from field and greenhouse drip 

irrigation application, and implied worker inhalation exposures from application of chloropicrin 

by shank injection, drip irrigation systems and at tree replant sites. Chloropicrin Manufacturer’s 

Task Force. DPR Registration data. Volume 199-0112. 

Roush, T. 2006. 2006 Update to the pesticide VOC inventory: estimated emissions 1990–2004. 

Memorandum to John S. Sanders, Ph.D., dated October 24, 2006. DPR. 

Segawa, R., B. Johnson, and T. Barry. 2000. Summary of off-site air monitoring for 

methyl bromide field fumigations. Memorandum dated January 21, 2000 to John S. Sanders, Ph.D. 

DPR. Environmental Monitoring Branch. Sacramento, California 95814. Available at: 

<http://www.cdpr.ca.gov/docs/empm/pubs/tribal/1offsiteMonitMebr-2.pdf>. 

Spurlock, F. 2002a. Summary of 1990-2000 VOC emissions inventory data. Memorandum 

to John S. Sanders, Ph.D., dated February 4, 2002. DPR. Available at: 

<http://www.cdpr.ca.gov/docs/pur/vocproj/sum0099.pdf>. 

Spurlock, F. 2002b. Methodology for determining VOC EPs of pesticideproducts. 

Memorandum to John S. Sanders, Ph.D., dated January 7, 2002. DPR. Available at: 

<http://www.cdpr.ca.gov/docs/pur/vocproj/intro.pdf>. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 26 

Spurlock, F. 2002c. Analysis of the historical and revised base year 1990 volatile organic 

compound emission inventories. Memorandum to Randy Segawa dated December 16, 2002. 

DPR. Available at: <http://www.cdpr.ca.gov/docs/pur/vocproj/base_year_inv.pdf>. 

Spurlock, F. 2004. 2004 Update to the pesticide VOC inventory: estimated emissions1990-2002. 

Memorandum to John S. Sanders, Ph.D., dated May 17, 2004.DPR. Available at: 

<http://www.cdpr.ca.gov/docs/pur/vocproj/060304em_inv.pdf>. 

Spurlock, F. 2005a. Revisions to procedures for estimating volatile organic compound emissions 

from pesticides. Memorandum to John S. Sanders, Ph.D., dated February 7, 2005. DPR. 

Available at: <http://www.cdpr.ca.gov/docs/pur/vocproj/voc_calc_revision020405.pdf>. 

Spurlock, F. 2006. 2006 Revisions to procedures for estimating volatile organic compound 

emissions from pesticides. Memorandum to John S. Sanders, Ph.D., dated July 18, 2006. DPR. 

Available at: <http://www.cdpr.ca.gov/docs/pur/vocproj/voc_calc_revision071805.pdf>. 

Stangellhini, M. 2006a. Analysis of Methyl Bromide emissions in the San Joaquin Valley in 

1990 and 2004. Consortium of Methyl Bromide Registrants. Document submitted to DPR in 

May 2006. 

Stangellhini, M. 2006b. Analysis of Chloropicrin emissions in the San Joaquin Valley in 

1990 and 2004. Chloropicrin Manufacturers Task Force. Document submitted to DPR in 

May 2006. 

Sullivan, D. H. Ajwa, and J. Radewald. 2005. Commercialization of enhanced water sealing for 

agricultural fumigants. USDA Research Grant 2005-00221. Sullivan Environmental Consulting, 

Inc. 1900 Elkin Street Suite 240, Alexandria ,VA 22308. 

Subramanian, P., L. Teesch and P.S. Thorne. 1996. Degradation of 3,5-Dimethyl-Tetrahyro-2H1,3,5-Thiadiazine-2-Thione in Aqueous Aerobic Media. Environmental Toxicology and 

Chemistry. Volume 15, No. 4, pp. 501–513. 

Wales, P. 2000. Evaluation of methyl isothiocyanate as a toxic air contaminant. 

Part A–Environmental Fate. DPR. Environmental Monitoring Branch. Sacramento, 

California 95814. TAC-2000-01A. 

Wesenbeeck, I. Van and A. M. Phillips. 2000. Field volatility of 1,3-D and chloropicrin from 

surface drip irrigation application of In-Line to vegetable beds under polyethylene tarp. Global 

Environmental Chemistry Laboratory B Indianapolis Lab, Dow AgroSciences LLC, 9330 

Zionsville Road, Indianapolis, Indiana 46268-1054. Study identification number: 990072. 
John S. Sanders, Ph.D. 

September 29, 2007 

Page 27 

Wilhelm, S. 2007. DPR VOC Inventory Analysis. Letter from Stephen Wilhelm to Randy 

Segawa, dated September 26, 2007. Chloropicrin Manufacturers’ Task Force. 

Wilson J.D., and W.K.N. Shum. 1992. A re-examination of the integrated horizontal flux method 

for estimating volatilization for circular plots. Agricultural and Forest Meteorology 57:281-295. 

Wofford, P., J. Levine, P. Lee, J. White, J. Hsu, T. Woroneicka, and S. Matsumoto. Monitoring a 

1,3-D/metam-sodium application in Del Norte County. 2005. California Environmental 

Protection Agency. DPR. Environmental Monitoring Branch. 1001 I Street, P.O. Box 4015, 

Sacramento, California 95812. EH05-04. 

Wofford, P., K.P. Bennett, J. Hernandez, and P. Lee. Air Monitoring for Methyl Isothiocyanate 

During a Sprinkler Application of Metam-Sodium. 1994. California Environmental Protection 

Agency. DPR. Environmental Monitoring Branch. 1001 I Street, P.O. Box 4015, Sacramento, 

California 95812. EH94-02. 

Yates, S.R., J. Gan, F.F. Ernst, A Mutziger, and M.V. Yates. 1996a. Methyl bromide emissions 

from a covered field: I. Experimental conditions and degradation in soil. Journal Environmental 

Quality. Volume 25:184-192. 

Yates, S.R., F.F. Ernst, J. Gan, F. Gao, and M.V. Yates. 1996b. Methyl bromide emissions from 

a covered field: II. Volatilization. Journal Environmental Quality. Volume 25:192-202. 

Yates, S.R., J. Gan, S.K. Papiernik, R. Dungan, and D. Wang. 2002. Reducing fumigant 

emissions after soil application. Phytopathology 92:1344-1348. 

Yates, S.R. Measuring herbicide volatilizations from bare soil. 2006. Environmental Science and 

Technology. 40:3223-3228. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 28 Table 1. Summary of methyl bromide emission estimates from DPR and registrant field studies. The methyl bromadjustment factors are twice the average emission values shown, based on the assumption that the peak 24-hour etotal emissions. 

Study ID1 Bed/Broadcast 

Tarpaulin 

Type Chisel Type 

Injection Depth 

(inches) 

Date 

Applied 

Peak Emissions 

in 24 hrs (%) 

SE1.1 Bed None Rearward curved 12 8/19/92 34 SE1.2 Bed None Rearward curved 12 9/24/92 56 SE1.3/EH127-2 Bed None Rearward curved 12 10/27/92 40 SE2.2 Broadcast None Forward curved 20 10/21/92 62 EH164-7 Broadcast None Forward curved 20 1/22/98 32 S104.2-1 Broadcast None Forward curved 24 3/8/93 44 S100B1.1 Broadcast None Forward curved 24 3/13/93 22 S110.1 Broadcast None Forward curved 24 10/31/95 8.4 TC199 Broadcast High barrier Nobel Plow 12 6/30/92 26 EH127-1 Broadcast High barrier Nobel Plow 12 10/26/92 16 EH150-6 Broadcast High barrier Nobel Plow 12 2/13/97 9.8 EH163-2 Broadcast High barrier Nobel Plow 12 8/21/97 40 EH164-5 Broadcast High barrier Nobel Plow 12 11/1/97 36 EH164-10A Broadcast High barrier Nobel Plow 12 6/5/98 36 EH164-10C Broadcast High barrier Nobel Plow 12 6/5/98 30 EH164-10E Broadcast High barrier Nobel Plow 12 6/7/98 17 EH164-10G Broadcast High barrier Nobel Plow 12 6/7/98 17 TC324.1 Broadcast High barrier Nobel Plow 12 7/25/98 6.8 EH163-4 Broadcast High barrier Nobel Plow 12 9/2/98 26 BR787.1A Broadcast High barrier Nobel Plow 12 6/24/99 20 BR787.2A Broadcast High barrier Nobel Plow 12 6/30/99 48 S110F1 Bed High barrier Rearward curved 6 7/13/93 6.2 EH164-2 Bed High barrier Rearward curved 6 9/8/97 68 EH164-11 Bed High barrier Rearward curved 6 10/6/98 100 BR787.1B Bed High barrier Rearward curved 6 6/24/99 100 BR787.1C Bed High barrier Forward curved 6 6/24/99 100 BR787.2B Bed High barrier Forward curved 6 6/30/99 76 BR787.2C Bed High barrier Rearward curved 6 6/30/99 76 EH150-2 Bed High barrier Rearward curved 6 12/12/96 100 EH164-6 Bed High barrier Rearward curved 6 12/17/97 100 

1 Study IDs beginning with EH are DPR studies, all others are registrant studies. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 29 Table 2. Summary of methyl bromide emission estimates from the literature. 

Broadcast Tarp 

Reference Study Type Soil Type Depth (cm) Emissions (%) Average 

(%) 

C

JEQ Vol 24:742 Field Silty Clay Loam 25 32 

40 

JEQ Vol 25:185 Field Sandy Loam 25 63 JEQ Vol 26:310 Column Sandy Loam 30 43 JEQ Vol 26:310 Column Sandy Loam 30 37 JEQ Vol 26:310 Column Sandy Loam 60 26 

Broadcast Nontarp 

Reference Study Type Depth (cm) Emissions (%) Average 

(%) 

C

JEQ Vol 24:742 Field Silty Clay Loam 25 89 

66 

JEQ Vol 26:310 Column Sandy Loam 20 82 JEQ Vol 26:310 Column Sandy Loam 30 71 JEQ Vol 26:310 Column Sandy Loam 60 38 ES&T Vol 30:1629 

Column Sandy Loam 30 77 

ES&T Vol 30:1629 

Column Loamy Sand 30 77 

ES&T Vol 30:1629 

Column Clay 30 37 
John S. Sanders, Ph.D. 

September 29, 2007 Page 30 Table 3. Summary of 1,3-D emission estimates. 

Reference 

Application 

Method Location 

Measured 

Emissions 

(%) 

Average 

Emissions (%) 

(interpolated 

to 18 inches) 

Gillis and Dowling (1998) 

Shank Broadcast -14" depth 

Salinas, CA 65 

651 Gillis and 

Dowling (1998) 

Shank Bed -12" depth Salinas, CA 65 

Knuteson et al. (1995) 

Shank Broadcast -20-22" depth 

Firebaugh, CA 26 

262 

Knuteson et al. (1992) 

Shank Broadcast -18" depth 

Salinas, CA 25 

Knuteson et al. (1999) Drip Salinas, CA 29 29 Wesenbeeck & Phillipps (2000) 

Drip Douglas, GA 29 

1 Shallow application 12 inches 2 Deep application 18 inches 
John S. Sanders, Ph.D. 

September 29, 2007 Page 31 Table 4. Summary of chloropicrin emission estimates. 

Reference Application Method Location Emissions (%) Average (%

Beard (1996) Broadcast/No Tarp Arizona 62.5 64.2 Beard (1996) Broadcast/No Tarp Arizona 61.4 Beard (1996) Bed/Tarp Arizona 68.6 

44.2 

Beard (1996) Broadcast/Tarp Arizona 62.3 Beard (1996) Broadcast/Tarp Washington 33.8 Beard (1996) Broadcast/Tarp Florida 36.5 Rotonardo (2004) Drip/low perm. tarp 15 11.8 Knuteson and Dolder (2000) Drip/low perm. tarp California 8.6 van Wesenbeeck and Phillips (2000) Drip/high perm.tarp Georgia 12.3 12.3 
John S. Sanders, Ph.D. 

September 29, 2007 Page 32 Table 5. Summary of MITC emission estimates. All calculations are on a 1-acre basis. See text for description of methods. 

Metam-Sodium Studies 

Reference Application Method 

MITC 

Emissions 

(lbs) 

Total MITC 

(lbs) 

Emissions 

(%) 

Merricks (1999) Standard Sprinkler 139 172 81 Merricks (1999) Standard Shank 63 86 73 Sullivan et al. (2005) Sprinkler w/2 Water Treatments 31 110 28 Merricks (2001) Sprinkler w/ 3 Water Treatments 39 172 23 Merricks (2001) Shank w/ 3 Water Treatments 16 86 19 Levine, et al. (2005) Nontarp drip 0.92 21 4.4 Levine, et al. (2005) Nontarp/intermittent drip 0.64 26.2 2.4 Li, et al. (2006) Tarp drip 3.58 16 20.5 Wofford (2005) Rototill 14 

Dazomet Studies 

Reference Application Method 

MITC 

Emissions 

(lbs) 

Total MITC 

(lbs) 

Emissions 

(%) 

Certis (2004) Surface 6.26 137 4.57 Fan, in progress Surface 45 105 42.9 Certis (2004) Surface incorporated 6.04 269 2.3 
John S. Sanders, Ph.D. 

September 29, 2007 Page 33 Table 6. 1990/91 frequency of fumigation methods used (method use fractions) in the Sacramento Metro nonatta

Fumigation Method1 

% of Amount Applied 

1,3-D1 Chloropicrin 

Methyl 

Bromide Metam3 Dazomet3 

Shallow injection w/ high permeability tarp or no tarp-broadcast 42 37 Shallow injection w/ low permeability tarp-broadcast Shallow injection w/ high permeability tarp or no tarp-bed 42 36 18 Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast 16 14 Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 2 100 Sprinkler 55 Sprinkler w/ 2 water treatments Sprinkler w/ 3 water treatments Flood 10 Drip w/ high permeability tarp or no tarp 10 Drip w/ low permeability tarp 5 Nonfield soil (structural/post-harvest) 13 

1 Fumigation methods are described in detail in the text. 2 Negligible amounts of 1,3-D were applied during 1990/91. 3 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

4 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 34 Table 7. 1990/91 frequency of fumigation methods used (method use fractions) in the San Joaquin Valley nonatt

Fumigation Method1 

% of Amount Applied 

1,3-D1 Chloropicrin 

Methyl 

Bromide Metam3 Daz

Shallow injection w/ high permeability tarp or no tarp-broadcast 29 29 Shallow injection w/ low permeability tarp-broadcast Shallow injection w/ high permeability tarp or no tarp-bed 29 29 33 Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast 42 42 Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 3 Sprinkler 60 Sprinkler w/ 2 water treatments Sprinkler w/ 3 water treatments Flood Drip w/ high permeability tarp or no tarp 2 Drip w/ low permeability tarp 2 Nonfield soil (structural/post-harvest) 

1 Fumigation methods are described in detail in the text. 2 Negligible amounts of 1,3-D were applied during 1990/91. 3 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

4 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 35 Table 8. 1990/91 frequency of fumigation methods used (method use fractions) in the Southeast Desert nonattain

Fumigation Method1 

% of Amount Applied 

1,3-D1 Chloropicrin 

Methyl 

Bromide Metam3 Dazo

Shallow injection w/ high permeability tarp or no tarp-broadcast 50 35 Shallow injection w/ low permeability tarp-broadcast Shallow injection w/ high permeability tarp or no tarp-bed 50 34 10 Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 1Sprinkler 30 Sprinkler w/ 2 water treatments Sprinkler w/ 3 water treatments Flood 50 Drip w/ high permeability tarp or no tarp 5 Drip w/ low permeability tarp 5 Nonfield soil (structural/post-harvest) 31 

1 Fumigation methods are described in detail in the text. 2 Negligible amounts of 1,3-D were applied during 1990/91. 3 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

4 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 36 Table 9. 1990/91 frequency of fumigation methods used (method use fractions) in the Ventura nonattainment are

Fumigation Method1 

% of Amount Applied 

1,3-D1 Chloropicrin 

Methyl 

Bromide Metam3 Dazo

Shallow injection w/ high permeability tarp or no tarp-broadcast 50 49 Shallow injection w/ low permeability tarp-broadcast Shallow injection w/ high permeability tarp or no tarp-bed 50 49 20 Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 1Sprinkler 50 Sprinkler w/ 2 water treatments Sprinkler w/ 3 water treatments Flood Drip w/ high permeability tarp or no tarp 15 Drip w/ low permeability tarp 15 Nonfield soil (structural/post-harvest) 3 

1 Fumigation methods are described in detail in the text. 2 Negligible amounts of 1,3-D were applied during 1990/91. 3 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

4 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 37 Table 10. 1990/91 frequency of fumigation methods used (method use fractions) in the South Coast nonattainme

Fumigation Method1 

% of Amount Applied 

1,3-D1 Chloropicrin 

Methyl 

Bromide Metam3 Da

Shallow injection w/ high permeability tarp or no tarp-broadcast 50 3 Shallow injection w/ low permeability tarp-broadcast Shallow injection w/ high permeability tarp or no tarp-bed 50 3 20 Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping Sprinkler 50 Sprinker w/ 2 water treatments Sprinkler w/ 3 water treatments Flood Drip w/ high permeability tarp or no tarp 15 Drip w/ low permeability tarp 15 Nonfield soil (structural/post-harvest) 95 

1 Fumigation methods are described in detail in the text. 2 Negligible amounts of 1,3-D were applied during 1990/91. 3 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

4 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 38 Table 11. 2004 frequency of fumigation methods used (method use fractions) in the Sacramento Metro nonattain

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Da

Shallow injection w/ high permeability tarp or no tarp-broadcast Shallow injection w/ low permeability tarp-broadcast 56 11 Shallow injection w/ high permeability tarp or no tarp-bed 21 Shallow injection w/ low permeability tarp-bed 33 6 Shallow injection w/ 2 water treatments Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast 100 Deep injection w/ low permeability tarp-broadcast 11 Rotovate/rototill/soil capping 15 Sprinkler 5 Sprinkler w/ 2 water treatments 30 Sprinkler w/ 3 water treatments Flood 10 Drip w/ high permeability tarp or no tarp 9 Drip w/ low permeability tarp 11 10 Nonfield soil (structural/post-harvest) 71 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 39 Table 12. 2004 frequency of fumigation methods used (method use fractions) in the San Joaquin Valley nonattai

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazom

Shallow injection w/ high permeability tarp or no tarp-broadcast 2 Shallow injection w/ low permeability tarp-broadcast 96 79 Shallow injection w/ high permeability tarp or no tarp-bed 16 Shallow injection w/ low permeability tarp-bed 2 1 Shallow injection w/ 2 water treatments 5 Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast 98 Deep injection w/ low permeability tarp-broadcast 1 16 Rotovate/rototill/soil capping 20 10Sprinkler 5 Sprinkler w/ 2 water treatments 25 Sprinkler w/ 3 water treatments Flood 5 Drip w/ high permeability tarp or no tarp 14 Drip w/ low permeability tarp 10 Nonfield soil (structural/post-harvest) 1 4 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 40 Table 13. 2004 frequency of fumigation methods used (method use fractions) in the Southeast Desert nonattainm

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazom

Shallow injection w/ high permeability tarp or no tarp-broadcast 4 Shallow injection w/ low permeability tarp-broadcast 69 77 Shallow injection w/ high permeability tarp or no tarp-bed 6 Shallow injection w/ low permeability tarp-bed 19 19 Shallow injection w/ 2 water treatments Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast Deep injection w/ low permeability tarp-broadcast 1 Rotovate/rototill/soil capping 100 Sprinkler 5 Sprinkler w/ 2 water treatments 10 Sprinkler w/ 3 water treatments Flood 60 Drip w/ high permeability tarp or no tarp 96 7 Drip w/ low permeability tarp 10 12 Nonfield soil (structural/post-harvest) 2 3 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 41 Table 14. 2004 frequency of fumigation methods used (method use fractions) in the Ventura nonattainment area

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazom

Shallow injection w/ high permeability tarp or no tarp-broadcast 2 Shallow injection w/ low permeability tarp-broadcast 48 63 Shallow injection w/ high permeability tarp or no tarp-bed 10 Shallow injection w/ low permeability tarp-bed 28 37 Shallow injection w/ 2 water treatments 15 Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarp-broadcast 4 Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 100 Sprinkler Sprinkler w/ 2 water treatments Sprinkler w/ 3 water treatments 20 Flood Drip w/ high permeability tarp or no tarp 94 5 Drip w/ low permeability tarp 24 50 Nonfield soil (structural/post-harvest) 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 42 Table 15. 2004 frequency of fumigation methods used (method use fractions) in the South Coast nonattainment 

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazom

Shallow injection w/ high permeability tarp or no tarpbroadcast Shallow injection w/ low permeability tarp-broadcast 40 61 Shallow injection w/ high permeability tarp or no tarp-bed 10 Shallow injection w/ low permeability tarp-bed 36 31 Shallow injection w/ 2 water treatments 15 Shallow injection w/ 3 water treatments Deep injection w/ high permeability tarp or no tarpbroadcast Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 100 Sprinkler 20 Sprinkler w/ 2 water treatments Sprinkler w/ 3 water treatments Flood Drip w/ high permeability tarp or no tarp 100 5 Drip w/ low permeability tarp 24 50 Nonfield soil (structural/post-harvest) 8 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 43 Table 16. Predicted fumigation methods if only “low-emission” methods used (predicted method use fractions) iMetro nonattainment area. 

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazome

Shallow injection w/ high permeability tarp or no tarp-broadcast Shallow injection w/ low permeability tarp-broadcast 89 14 Shallow injection w/ high permeability tarp or no tarp-bed Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments 18 Shallow injection w/ 3 water treatments 18 Deep injection w/ high permeability tarp or no tarp-broadcast 100 Deep injection w/ low permeability tarp-broadcast 11 12 Rotovate/rototill/soil capping 100 Sprinkler Sprinkler w/ 2 water treatments 23 Sprinkler w/ 3 water treatments 22 Flood Drip w/ high permeability tarp or no tarp 9 Drip w/ low permeability tarp 10 Nonfield soil (structural/post-harvest) 74 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 44 Table 17. Predicted fumigation methods if only “low-emission” methods used (predicted method use fractions) iValley nonattainment area. 

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazom

Shallow injection w/ high permeability tarp or no tarp-broadcast Shallow injection w/ low permeability tarp-broadcast 98 80 Shallow injection w/ high permeability tarp or no tarp-bed Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments 11 Shallow injection w/ 3 water treatments 2 10 Deep injection w/ high permeability tarp or no tarp-broadcast 98 Deep injection w/ low permeability tarp-broadcast 16 Rotovate/rototill/soil capping 20 10Sprinkler Sprinker w/ 2 water treatments 18 Sprinkler w/ 3 water treatments 17 Flood Drip w/ high permeability tarp or no tarp 14 Drip w/ low permeability tarp 2 10 Nonfield soil (structural/post-harvest) 4 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 45 Table 18. Predicted fumigation methods if only “low-emission” methods used (predicted method use fractions) inonattainment area. 

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazo

Shallow injection w/ high permeability tarp or no tarp-broadcast Shallow injection w/ low permeability tarp-broadcast 89 100 Shallow injection w/ high permeability tarp or no tarp-bed Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments 3 Shallow injection w/ 3 water treatments 4 3 Deep injection w/ high permeability tarp or no tarp-broadcast Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 10Sprinkler Sprinkler w/ 2 water treatments 38 Sprinkler w/ 3 water treatments 37 Flood Drip w/ high permeability tarp or no tarp 96 7 Drip w/ low permeability tarp 11 12 Nonfield soil (structural/post-harvest) 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 46 Table 19. Predicted fumigation methods if only “low-emission” methods used (predicted method use fractions) inonattainment area. 

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazo

Shallow injection w/ high permeability tarp or no tarpbroadcast Shallow injection w/ low permeability tarp-broadcast 76 100 Shallow injection w/ high permeability tarp or no tarp-bed Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments 13 Shallow injection w/ 3 water treatments 2 12 Deep injection w/ high permeability tarp or no tarpbroadcast 4 Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 1Sprinkler Sprinkler w/ 2 water treatments 10 Sprinkler w/ 3 water treatments 10 Flood Drip w/ high permeability tarp or no tarp 94 5 Drip w/ low permeability tarp 24 50 Non-field soil (structural/post-harvest) 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 47 Table 20. Predicted fumigation methods if only “low-emission” methods used (predicted method use fractions) inonattainment area. 

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazom

Shallow injection w/ high permeability tarp or no tarpbroadcast Shallow injection w/ low permeability tarp-broadcast 76 94 Shallow injection w/ high permeability tarp or no tarp-bed Shallow injection w/ low permeability tarp-bed Shallow injection w/ 2 water treatments 13 Shallow injection w/ 3 water treatments 12 Deep injection w/ high permeability tarp or no tarpbroadcast Deep injection w/ low permeability tarp-broadcast Rotovate/rototill/soil capping 100 Sprinkler Sprinkler w/ 2 water treatments 10 Sprinkler w/ 3 water treatments 10 Flood Drip w/ high permeability tarp or no tarp 100 5 Drip w/ low permeability tarp 24 50 Nonfield soil (structural/post-harvest) 6 

1 Fumigation methods are described in detail in the text. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 48 Table 21. Estimates of pesticide VOC emissions without application method adjustment factors (unadjusted stan1991, and 2004. The 1991 goal is a 20% reduction of the 1991 emissions. 

Nonattainment 

Area Year 

Unadjusted VOC Emissions, May – October (tons/day) 

1,3-D Chloropicrin 

Methyl 

Bromide Metam Dazomet 

Na 

Tetrathiocarbonate1 Oth

Pesti

1990 0.000 0.036 0.400 0.022 0.000 0.000 2.4

Sacramento 1991 0.000 0.035 0.319 0.013 0.000 0.000 2.7

Metro 2004 0.087 0.007 0.061 0.009 0.000 0.000 1.2

1991 goal 1990 0.005 0.208 5.158 2.017 0.000 0.006 15.3

San Joaquin 1991 0.000 0.301 7.493 1.461 0.000 0.000 12.8

Valley 2004 4.550 0.320 2.364 6.280 0.025 0.113 11.6

1991 goal 

1990 0.000 0.011 0.902 0.010 0.000 0.000 0.3

Southeast Desert 1991 0.002 0.014 0.414 0.019 0.000 0.000 0.3

2004 0.025 0.094 0.296 0.832 0.011 0.005 0.2

1991 goal 

1990 0.000 0.929 2.785 0.160 0.000 0.001 0.6

Ventura 1991 0.000 0.745 2.531 0.085 0.000 0.000 0.5

2004 1.543 3.322 3.317 0.482 0.009 0.000 0.61991 goal 1990 0.000 0.174 9.248 0.004 0.000 0.000 1.4

South Coast 1991 0.005 0.166 3.489 0.040 0.000 0.000 1.4

2004 0.198 0.449 0.669 0.042 0.024 0.000 1.2

1991 goal 

1 Sodium (Na) tetrathiocarbonate. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 49 Table 22. Summary of fumigant application method adjustment factors. 

Fumigation Method1 

% of Amount Applied 

1,3-D Chloropicrin 

Methyl 

Bromide Metam2 Dazome

Shallow injection w/ high permeability tarp or no tarp-broadcast 65 64 74 not applicable not applicaShallow injection w/ low permeability tarpbroadcast not applicable 44 48 not applicable not applicaShallow injection w/ high permeability tarp or no tarp-bed not applicable 64 100 77 not applicaShallow injection w/ low permeability tarp-bed not applicable 64 100 not applicable not applicaShallow injection w/ 2 water treatments not applicable not applicable not applicable 28 not applicaShallow injection w/ 3 water treatments 44 43 not applicable 21 not applicaDeep injection w/ high permeability tarp or no tarp-broadcast 26 64 74 not applicable not applicaDeep injection w/ low permeability tarp-broadcast not applicable 44 48 not applicable not applicaRotovate/rototill/soil capping not applicable not applicable not applicable 14 17 Sprinkler not applicable not applicable not applicable 77 not applicaSprinkler w/ 2water treatments not applicable not applicable not applicable 28 not applicaSprinkler w/ 3 water treatments not applicable not applicable not applicable 21 not applicaFlood not applicable not applicable not applicable 77 not applicaDrip w/ high permeability tarp or no tarp 29 12 not applicable 9 not applicaDrip w/ low permeability tarp not applicable 12 not applicable 9 not applicaNonfield soil (structural/post-harvest) not applicable not applicable 100 not applicable not applica

1 Fumigation methods are described in detail in DPR’s proposed regulations. 2 DPR assumes 100% conversion of metam and dazomet to MITC and percentages are relative to the amount of M

3 DPR assumes 100% conversion of sodium (Na) tetrathiocarbonate to carbon disulfide and percentages are relat

carbon disulfide applied. 
John S. Sanders, Ph.D. 

September 29, 2007 Page 50 Table 23. Estimates of pesticide VOC emissions with application method adjustment factors for 1990, 1991, 200emissions if only “low-emission” methods are used under the 2008 regulations. The goal is a 20% reduction of th

Nonattainment 

Area Year 

Field Adjusted VOC Emissions, May – October (tons/day) 

1,3-D Chloropicrin 

Methyl 

Bromide Metam Dazomet 

Na Tetrathiocarbonate1 Othe

Pesticid

Sacramento 

Metro 

1990 0.000 0.023 0.347 0.012 0.000 0.000 2.443 1991 0.000 0.022 0.277 0.007 0.000 0.000 2.749 2004 0.023 0.003 0.067 0.005 0.000 0.000 1.205 2004 low3 0.023 0.003 0.066 0.002 0.000 0.000 1.205 

Goal (1991) 

San Joaquin 

Valley 

1990 0.000 0.133 4.225 1.150 0.000 0.001 15.351991 0.000 0.193 6.110 0.823 0.000 0.000 12.852004 1.226 0.149 1.201 2.901 0.004 0.011 11.662004 low3 1.206 0.144 1.149 1.144 0.004 0.011 11.66

Goal (1991) 

Southeast 

Desert 

1990 0.000 0.007 0.821 0.007 0.000 0.000 0.315 1991 0.002 0.009 0.376 0.013 0.000 0.000 0.382004 0.008 0.044 0.176 0.533 0.002 0.000 0.237 2004 low3 0.007 0.038 0.142 0.183 0.002 0.000 0.237 Goal (1991) 

Ventura 

1990 0.000 0.594 2.435 0.090 0.000 0.000 0.633 1991 0.000 0.477 2.215 0.048 0.000 0.000 0.554 2004 0.464 1.427 2.224 0.069 0.002 0.000 0.640 2004 low3 0.458 1.236 1.593 0.078 0.002 0.000 0.640 

Goal (1991) 

South Coast 

1990 0.000 0.111 9.208 0.002 0.000 0.000 1.426 1991 0.005 0.106 3.466 0.022 0.000 0.000 1.466 2004 0.058 0.164 0.455 0.017 0.004 0.000 1.217 2004 low3 0.058 0.166 0.342 0.007 0.004 0.000 1.217 

Goal (1991) 

1 Sodium (Na) tetrathiocarbonate. 2 VOC emissions for other pesticides (nonfumigants) use the EPs without any adjustment for field conditions. 3 2004 low shows the predicted 2004 emissions if all fumigant applications used a “low-emission” application m
John S. Sanders, Ph.D. 

September 29, 2007 Page 51 Table 24. Maximum fumigant emissions (fumigant emission limit) that would achieve the goal of a 20% reductiVOC emissions, assuming VOC emissions from nonfumigant (other) pesticides remain the same as 2004. The 20and the percentage reduction of these emissions needed to achieve the emissions goal are also shown. 

Nonattainment Area 

Field Adjusted VOC Emissions, May–October (tons/day) A

Fum

Red

Ac

Emissions 

Goal 

2004 Emissions From 

Other Pesticides 

Max Fumigant 

Emissions That 

Achieve Goal1 

2004 Fumigant 

Emissions 

Sacramento Metro 2.444 1.205 1.239 0.098 -116San Joaquin Valley 15.984 11.669 4.315 5.492 Southeast Desert 0.624 0.237 0.387 0.763 Ventura 2.634 0.640 1.994 4.186 South Coast 4.052 1.217 2.835 0.698 -30

1 Maximum Fumigant Emissions That Achieve Goal calculated by subtracting the 2004 Emissions From Other P

Emissions Goal. 

2 % reduction based on the difference between the Max Fumigant Emissions That Achieve Goal and the 2004 Fu

assuming emissions from other pesticides remain the same as 2004. Examples: The 2004 fumigant emissions in increase by 1164% and still meet the emissions goal. The 2004 fumigant emissions in San Joaquin Valley must to meet the emissions goal.