PEER-REVIEWED REPORT

UPDATING OZONE CALCULATIONS AND

EMISSIONS PROFILES FOR USE IN THE

ATMOSPHERIC AND HEALTH EFFECTS

FRAMEWORK MODEL

 Stratospheric Protection Division 

Office of Air and Radiation 

U.S. Environmental Protection Agency 

Washington, D.C. 20460 

February 27, 2015
PREFACE

This report was prepared by the U.S. Environmental Protection Agency (EPA) with the support of its 

contractor, ICF International. Key contributors included Melissa Fiffer and Robert Landolfi from the EPA, 

Dr. Rawlings Miller, Jessica Kyle, and Mark Wagner from ICF, and Dr. Sasha Madronich from the National 

Center for Atmospheric Research (NCAR). This report describes updates to the EPA’s Atmospheric and 

Health Effects Framework (AHEF), which models adverse human health effects associated with a 

depleted stratospheric ozone layer. The AHEF is updated regularly to reflect new information and 

science. The updates presented in this report incorporate new values for ODS characteristics and an 

updated global emissions profile. Because these updates are specific to one AHEF module, this report 

does not attempt to comprehensively describe the data and methodology behind the AHEF. For a fuller 

description of the AHEF methodology, please see prior peer-reviewed EPA reports Human Health 

Benefits of Stratospheric Ozone Protection (2006)1 and Protecting the Ozone Layer Protects Eyesight: A 

Report on Cataract Incidence in the United States Using the AHEF Model (2010).2

The initial report was drafted in 2012. In 2013, the draft final report was peer reviewed for its technical 

content by Dr. Stephen Montzka of the National Oceanic and Atmospheric Administration, and 

subsequently by Dr. Robyn Lucas of the National Centre for Epidemiology & Population Health at 

Australian National University. The peer reviewers were asked to draw upon their expertise in ozone 

depleting substance emissions and ultraviolet radiation health modeling and science to comment on 

whether the data inputs, approach, and methodologies presented in the report reflect sound scientific 

and analytical practice, and adequately address the questions at hand.

Written comments were received from the peer reviewers. Comments and data received were used to 

adjust the draft methodology to rely on the global ODS emissions profiles from the World Meteorological 

Organization’s (WMO) Scientific Assessment of Ozone Depletion: 2010 (WMO 2011), which represented

the most up-to-date understanding of ozone depletion at the time the report was being finalized (mid2013). A number of comments also identified areas for technical clarification and opportunities for 

future improvements. Given the extent of changes made in response to comments received, the revised 

report was re-reviewed by Dr. Stephen Montzka and Dr. Michael Kurylo of the National Aeronautics and 

Space Administration in late 2014 and early 2015. All comments of the reviewers were considered, and 

the document was modified accordingly. 

The EPA wishes to acknowledge everyone involved in the development of this report and to thank the 

peer reviewers for their time, effort, and expert guidance. The involvement of the peer reviewers greatly 

enhanced the technical soundness of this report. The EPA accepts responsibility for all information 

presented and any errors contained in this document.

Stratospheric Protection Division

Office of Atmospheric Programs

U.S. Environmental Protection Agency

Washington, DC 20460

1 http://www.epa.gov/ozone/science/effects/AHEFApr2006.pdf

2 http://www.epa.gov/ozone/science/effects/AHEFCataractReport.pdf

i 
ACRONYMS

AFEAS Alternative Fluorocarbons Environmental Acceptability Study

AGAGE Advanced Global Atmospheric Gases Experiment

AHEF Atmospheric and Health Effects Framework

BAF Biological amplification factor

BCC Basal cell carcinoma

CFC Chlorofluorocarbon

CCM Chemistry-climate models

CMM Cutaneous malignant melanoma

DU Dobson units

EESC Equivalent effective stratospheric chlorine

HCFC Hydrochlorofluorocarbon

IPCC Intergovernmental Panel on Climate Change

MP Montreal Protocol

NASA National Aeronautics and Space Administration

NCI National Cancer Institute

NHANES National Health and Nutrition Examination Study

NMSC Non-melanoma skin cancer

NOAA National Oceanic and Atmospheric Administration

ODS Ozone-depleting substance

ppb Parts per billion

ppt Parts per trillion

QBO Quasi-biennial oscillation

ROW Rest of world

SCC Squamous cell carcinoma

SEER Surveillance, Epidemiology, and End Results Program

SRES Special Report Emissions Scenarios

TEAP Technology and Economic Assessment Panel

TOMS Total Ozone Mapping Spectrometer

UNEP United Nations Environment Program

USGCRP U.S. Global Change Research Program

UV Ultraviolet

VM EPA’s Vintaging Model

WMO World Meteorological Organization

ii
TABLE OF C ONTENTS

Preface ....................................................................................................................................................................................................... i

Acronyms ................................................................................................................................................................................................ ii

Table of Contents ............................................................................................................................................................................... iii

Chapter 1: Introduction ............................................................................................................................................................ 1

Chapter 2: Updating ODS Emission Profiles ..................................................................................................................... 3

Selection of a New Global Emissions Profile ....................................................................................................................... 4

Comparison of ODS Emissions Profiles ................................................................................................................................. 5

Chapter 3: Updates to AHEF Ozone Calculations ........................................................................................................... 8

Updates to EESC Inputs and Impacts on Model Estimation ......................................................................................... 8

Updates to Ozone Calculations and Impacts on Model Estimation ........................................................................ 11

Chapter 4: Results of Updates ............................................................................................................................................. 14

Comparison of EESC ................................................................................................................................................................... 14

Comparison of Ozone ................................................................................................................................................................. 18

Comparison of Health Benefits .............................................................................................................................................. 19

Chapter 5: Future Modeling and Research .................................................................................................................... 21

Emissions Profiles for Future ODS Control Policy Scenarios ................................................................................... 21

Future AHEF Updates ................................................................................................................................................................ 22

References ........................................................................................................................................................................................... 23

Appendix A: Potential Global ODS and ODS Substitute Data Sources ........................................................................ 25

Appendix B: Emission Profile Estimates from 1950 through 2100 ............................................................................ 26

Appendix C: Comparison of Emission Profiles by Species .............................................................................................. 27

Appendix D: Parameters and Coefficients Used to Inform the EESC and Ozone Calculations ........................ 30

Appendix E: Total Column Ozone for Modeled Policy Scenarios ................................................................................. 32

Appendix F: Explanation of Differences between VM1999 and VM2012 ................................................................ 33

iii
Chapter 1: I NTRODUCTION

The Atmospheric and Health Effects Framework (AHEF) was created in the mid-1980s to assess the 

adverse human health effects associated with a depleted stratospheric ozone layer. Historically, the 

AHEF has estimated the probable increases in skin cancer mortality, skin cancer incidence, and 

cataract incidence in the United States that result from ozone-depleting substance (ODS) emission 

scenarios relative to a 1979–1980 baseline (i.e., prior to significant ozone depletion). This baseline is 

defined as the health effects that would have occurred if the ozone concentrations that existed in 

1979–1980 had been maintained through the time period modeled. The AHEF has also been 

historically used to evaluate the U.S. health benefits associated with progressively stronger ozone layer 

protection policies under the Montreal Protocol on Substances that Deplete the Ozone Layer and its 

associated amendments and adjustments. 

The AHEF consists of a series of independent modules (e.g., emissions, ozone projections, ultraviolet 

exposure, and health effects modules) that estimate U.S. health benefits related to reductions in ODS 

emissions. Figure 1 presents an overview of the modules within the AHEF.

Figure 1: Overview of the AHEF Modules

Project Ozone Depletion

(Vintaging and UIUC Modules)

Biological Amplification Factor

(Statistical Regression Analysis Dose 

Response Curve)

Project Population 

Historical data on rate of 

health impact per 100,000

 2005 Census Bureau Population

 projected population rates 

Action spectrum

Historical data on 

rate of health 

impact per 100,000

 Population data

Population-Weighted % Change 

in UV Exposure

(Exposure Module) 

Determine the Absolute Number of 

Additional Cases/Deaths

(Effects Module)

Amount of Population

Affected Given Baseline 

Incidence 

UV Exposure Weighted 

by Action Spectrum

(TUV Radiation Module)

Consumption of ODS

Market growth rates

TOMS satellite data

Historical ozone concentrations &

ODS emissions estimates

The AHEF’s ability to accurately project changes in ozone layer depletion is critical to its purpose of 

estimating the health benefits associated with various policy changes. This report summarizes 

updates to the AHEF module known as the “Ozone Maker," which projects ozone depletion based on 

global ODS emissions profiles (in the “Project Ozone Depletion” module, as shown in Figure 1). These 

updates are two-fold: (1) updates to the input parameters and calculations in the Ozone Maker; and 

(2) replacing the global ODS emissions profiles previously in use by AHEF with those developed for the 

World Meteorological Organization’s (WMO) Scientific Assessment of Ozone Depletion: 2010, which 

 1 
represented the most up-to-date understanding of ozone depletion at the time this report was being 

finalized (WMO 2011). This report describes in detail each of these updates and provides an analysis 

of how these changes affect the health benefits estimated by the AHEF. For a more comprehensive 

description of the entire AHEF model, please see EPA (2006) and EPA (2010), as briefly described in 

Box 1. 

This report is organized as follows:

 Chapter 2 revises the approach in the development of global emissions profiles for use in AHEF

by incorporating the global ODS emissions profiles from WMO’s 2010 assessment.

 Chapter 3 presents updates to the ozone projections module, including updates to the input

parameters and calculations of equivalent effective stratospheric chlorine (EESC) and total

column ozone.

 Chapter 4 evaluates the overall changes in EESC, total column ozone, and estimated health

benefits associated with the updates to the AHEF as described in Chapters 2 and 3.

 Chapter 5 provides a description of potential future work including the proposed methodology

for developing future global ODS emissions profiles to reflect new policy scenarios.

Box 1: Previous Updates and Peer Reviews of the AHEF

The AHEF was significantly updated in 2003 to incorporate new data and findings from various 

research projects. These revisions included: (1) recalibrated and refined stratospheric ozone 

concentration measurements; (2) improved forecasts of the impact of changing ozone concentrations 

on ultraviolet (UV) radiation intensity at the Earth’s surface; (3) updated information on the 

biological effects of UV radiation of different wavelengths (action spectra), and how age and year of 

birth affect the induction of skin cancers and other human health effects; (4) improved estimation of 

projected skin cancer mortality rates, based on more recent and reliable epidemiological data; (5) 

removal of the cataract module until an agreed upon dose-response relationship became available; 

and (6) updated population data. These updates were tested and presented in the EPA 2006 Peer 

Reviewed Report, “Human Health Benefits of Stratospheric Ozone Protection.” 

In a 2010 peer-reviewed report, Protecting the Ozone Layer Protects Eyesight: A Report on Cataract 

Incidence in the United States Using the AHEF Model, EPA reintroduced the model’s capability to 

estimate changes in cataract incidence by sex and skin type. The updates that enabled AHEF to model 

cataract incidence included updated information on the biological effects of UV radiation, including 

dose-response data by skin type and sex; and more recent epidemiological data. 

2
Chapter 2: UPDATING ODS EMISSION PROFILES

The AHEF requires input of global ODS emissions into the ozone projections module to estimate 

latitudinal ozone projections (U.S. EPA 2012). Figure 2 represents the historical relationship between 

ODS emissions and stratospheric ozone projections within the AHEF. While this figure represents the 

traditional approach for developing global emissions profiles and ozone changes in the AHEF, this 

methodology has been adjusted to accommodate other datasets on a scenario-by-scenario basis, 

dependent on analytical needs. For example, for an analysis of stratospheric ozone impacts by highspeed civil transport, calculations of ozone changes were based on results from the Commonwealth 

Scientific and Industrial Research Organization (CSIRO) model (NASA/EPA 2001). 

Figure 2: Schematic Diagram of Historical Method for Relating Emissions 

to Stratospheric Ozone Projections in the AHEF

Vintaging

Model

Apply 

Ratio 

from U.S. 

to Global

Ozone 

Maker

Global Emissions 

Profile

U.S. Emissions

Profile

Historically, U.S. ODS emissions as estimated by EPA’s Vintaging Model (VM) (described in Box 2 

below) have been multiplied by a U.S.-to-global emission factor to extrapolate global ODS emissions for 

use by the AHEF. This emission factor has been periodically revisited. In its initial design, AHEF used a 

ratio of 40% United States, 40% Europe, and 20% Rest of World (ROW). The emission factor currently 

in use was estimated in the 1990s, when U.S. ODS emissions represented roughly one-third of global 

emissions (i.e., 33% U.S., 33% Europe, and 33% ROW). 

Since the emission factor was last updated, relative contributions among these three segments has 

evolved. Both developed and developing countries have made significant progress towards the 

phaseout of ODS, and the Montreal Protocol has also been amended to control new chemicals and 

accelerate the phaseout of hydrochlorofluorocarbons (HCFCs).3 The result is that developing 

countries now account for a growing proportion of ODS emissions, while developed countries, 

including the United States, account for a smaller proportion. 

Given these trends and the flux in these emission relationships, it was determined that the emission 

factor approach should be replaced with a new global ODS emission profile that reflected the Montreal 

Protocol as currently amended. Updating the AHEF with a new global emissions profile allows 

circumvention of the first three steps in the historical schematic shown in Figure 2 above, effectively 

eliminating the need for a U.S.-to-global emissions factor.

3 The Parties to the Montreal Protocol have adjusted the Montreal Protocol five times since its initial adoption to 

accelerate the reductions required on chemicals already covered by the protocol, including most recently in 2007 

when the Parties adopted the 2007 Montreal Adjustment that accelerated the phaseout of HCFCs. The Parties have 

also amended the protocol four times to enable the control of new chemicals, among other actions.

3
Selection of a New Global Emissions Profile

Over the past decade, a number of 

international ODS datasets have become 

available. Appendix A presents 16 potential 

datasets that were considered for the AHEF 

based on criteria of authority, independence, 

timeliness (i.e., how recent is the inventory), 

global scale, data output (e.g., emissions, 

production, or consumption), projected 

timeline, and granularity. Ultimately, the WMO 

A1 Baseline emissions profile detailed in the 

WMO 2010 assessment was selected (WMO 

2011). The WMO (2011) A1 Baseline 

emissions profile accounts for the 1987 

Montreal Protocol and its associated 

amendments and adjustments through 2007. 

This dataset provides species-specific data at a 

global scale, is informed by observational data, 

provides ODS emissions estimates from 1950 

to 2100, is compiled based on a number of 

recently developed international ODS datasets 

(as described below), and is globallyrecognized as representing the current state of 

the science. 

The WMO (2011) A1 Baseline includes ODS 

emissions from 1950 to 2100 based on 

historical and projected mixing ratios, as 

shown in Appendix B. The historical mixing 

ratios are from 1950 to 2009 and are derived 

from observations from NOAA and Advanced Global Atmospheric Gases Experiment (AGAGE) global 

sampling networks. For years before ongoing observations are available, the historical mixing ratio 

trends are derived from (1) when available, measured mixing ratios in firn-air samples, and (2) 

modeled mixing ratios from consideration of industrial production magnitudes (e.g., the Alternative 

Fluorocarbons Environmental Acceptability Study [AFEAS]). The projected mixing ratios are based on

production of ODS reported to the United Nations Environment Program (UNEP), estimates of the 

bank sizes of ODS for 2008 from the Technology and Economic Assessment Panel (TEAP); approved 

essential use exemptions for CFCs, critical-use exemptions for methyl bromide, and production 

estimates of methyl bromide for quarantine and pre-shipment use. When NOAA and AGAGE 

observations are available (this varies by species), the mixing ratio is an average of the two network 

observations.4 

There is inherent uncertainty associated with data on ODS emissions, whether they are derived from

top-down models, bottom-up models, or extrapolated from atmospheric measurements, and the WMO 

2010 assessment is no exception. All datasets are affected by uncertainty in emissions profiles and 

ODS characteristics, such as species lifetimes, transport of ODS to the stratosphere, composition of the 

future atmosphere, and other factors.

4 See Table 5A-2 in the WMO (2011) report for detailed discussion of how the mixing ratio for each species was 

developed.

4

Box 2: EPA’s Vintaging Model

EPA’s Vintaging Model (VM) estimates the annual 

chemical emissions in the United States from 

industry sectors that have historically used ODS, 

including air conditioning, refrigeration, foams, 

solvents, aerosols, and fire protection. Within 

these industry sectors, there are over 60 

independently modeled end uses. The model uses 

information on the market size and growth for 

each end use, as well as a history and projections 

of the market transition from ODS to alternatives.

Prior to the updates described in this report, the 

AHEF’s emission profiles were developed based on 

the 1999 version of the VM. The VM is updated on 

a regular basis to reflect changes in the market and 

new industry information. Since 1999, the VM has 

been significantly enhanced to expand the 40 end

uses provided in the 1999 version to now include 

60 end uses, with new end uses added primarily in 

the industrial and commercial refrigeration and 

air-conditioning sectors. The VM has also been 

updated to better reflect the lifetime and emissions 

profiles of existing end uses, extend emissions 

projections out to 2050, and account for the 

accelerated phaseout schedule of HCFC 

consumption agreed to by the Montreal Protocol 

Parties in 2007.
For the observation data used in the WMO dataset, there is uncertainty due to instrument calibration 

and modeling errors. That said, these independent sampling programs for determining ODSs’ global 

mixing ratios have improved substantially over time, with differences now typically on the order of a 

few percent or less (e.g., see Table 1-1 of WMO [2011]). In addition, there is uncertainty in the future 

bank projections that arises from estimates of the amount of material in the ODS bank reservoir and 

the rate at which the material leaks or is released from the bank.

Comparison of ODS Emissions Profiles 

This section compares (a) the WMO (2011) A1 Baseline global emission profile with (b) the emission 

profile previously used in the AHEF, which was based on EPA’s Vintaging Model and the application of 

a U.S.-to-global emissions factor. For the purposes of this comparison, the former is called the WMO 

(2011) A1 Baseline and the latter is called VM1999.

Each emissions profile contains emissions by ODS species and year to be used as input to the Ozone 

Maker module. Table 1 provides a summary of the species data available from each emission data set. 

A comparison was conducted across each like ODS species over time to illustrate potential differences 

that could affect the AHEF simulation results.

Table 1: Comparison of Selected Global ODS Emission Data Sources5

Dataset Source CFCs HCFCs Other ODS

Years

Historical Projected/

Modeled

VM1999 U.S. EPA 

(2006)

11, 12, 

113, 114, 

115

22, 123, 

124, 141b, 

142b

CCl4, MCF, Halon 1211, 

Halon 1301

1936–1998 1999–2050

WMO 

(2011) 

A1 

Baseline 

WMO 

(2011)

11, 12, 

113, 114, 

115

22, 141b, 

142b

CCl4, MCF, Halon 1211, 

Halon 1301, CH3Br, 

Halon 1202, Halon 2402

1950–2009 2009–2100

To understand the implications of updating the AHEF emissions profiles to those developed for the 

WMO 2010 assessment, each ODS species’ emissions were compared as modeled by the VM1999 and 

WMO (2011) A1 Baseline. This section describes the differences of the changes between CFCs and 

HCFCs (see Appendix C for detailed figures comparing all ODS species).

Global CFC and HCFC emissions from 1980 to 2050 were visually compared for the VM1999 and WMO 

(2011) A1 Baseline (see Figure 3). As shown, there is broad consistency between the two datasets 

regarding the historical and projected emissions profile of CFCs. This consistency comes in part from 

the step down requirements for the CFC phaseout mandated by the Montreal Protocol. Quantitative

comparison of these emission estimates suggests a 25% difference from 1980 to 2050. Overall, the 

CFC emission estimates are within the same order of magnitude between the two datasets. 

In Figure 3, the HCFC comparison reveals more disparity in the historical and projected emissions 

between the two datasets, as would be expected because the phaseout of HCFCs has been accelerated 

and the transition from HCFCs to alternatives is still underway. These curves suggest an approximate 

50% difference between the two datasets. In part, this difference is because the VM1999 is derived 

from U.S. emissions and the HCFC phaseout is further along in the United States than in countries

operating under Article 5(1) of the Montreal Protocol (i.e., developing countries). 

5The VM1999 assumes a background concentration for methyl bromide.

5 
Figure 3: CFC and HCFC Emission Estimates

Note: The jump in VM1999 HCFC emissions in 2045 reflects the retirement of foam stock blown with HCFCs; these 

emissions may be controlled by future policy regimes. The WMO_A1_Baseline scenario represents the WMO (2011) A1 

Baseline scenario.

A further comparison by CFC and HCFC species was conducted for the year 2000 (see Appendix C for a

more detailed comparison of how CFC and HCFC species emissions vary over time between the two 

datasets). This individual species level of comparison is important, as the AHEF module that estimates 

ozone depletion takes into account the different atmospheric properties of each ODS (e.g., atmospheric 

lifetime, stratospheric release factors, and the number of reactive chlorine and bromine atoms). Figure 

4 illustrates ODP-weighted emission contributions of CFCs by species included in each dataset for the 

year 2000.6 CFC-12 represents the largest contributor to ODP-weighted CFC emissions for both 

datasets, followed by CFC-11, while ODP-weighted emissions of CFC-114 and CFC-115 are minimal in 

2000.

Figure 4: ODP-Weighted CFC Emission Contribution in 2000

6 CFCs and HCFCs contributing 0.5% or less to the total CFC or HCFC emissions, respectively, are not represented in 

the figures. The ODPs used for CFC species are as follows: 1 for CFC-11; 0.82 for CFC-12; 0.85 for CFC-113; 0.58 for 

CFC-114; 0.57 for CFC-115.

0

50

100

150

200

250

300

350

NOAA VM 1999 VM 2011 TEAP

ODP-Weighted Emissions (kt/yr)

CFC-115

CFC-114

CFC-113

CFC-12

CFC-11

6
Similarly, Figure 5 compares the relative ODP-weighted contribution of each HCFC species for the year 

2000.7 The VM1999 dataset provides estimates for all HCFC species; the WMO (2011) A1 Baseline 

dataset provides estimates of all species except HCFC-124 and HCFC-123. For both datasets, HCFC-22 

is the greatest contributor to OPD-weighted HCFC emissions. HCFC-141b represents a fairly consistent 

portion of the ODP-weighted HCFC emission total for each of the datasets. The contribution of the 

remaining HCFCs to total ODP-weighted HCFC emissions varies with each dataset.

Figure 5: ODP-Weighted HCFC Emission Contribution in 2000

As expected, this comparison demonstrated some changes due to the updated input parameters for 

EESC and in emissions by species when using the WMO (2011) A1 Baseline Scenario. Moving forward, 

the AHEF will rely on the state-of-the-science WMO (2011) A1 Baseline emissions profile to represent 

the effects of the Montreal Protocol as ratified in 1987 and all of its amendments and adjustments 

through 2007. In the future, AHEF may be updated to account for new global emissions profiles 

released as part of forthcoming WMO Ozone Assessments.

The next chapter further explores the implications of using the WMO (2011) A1 Baseline emission 

profile on AHEF estimates of EESC, column ozone, and human health effects.

7 The following ODP values were used for HCFC species: 0.04 for HCFC-22; 0.02 for HCFC-123; 0.022 for HCFC-124; 

0.12 for HCFC-141b; 0.07 for HCFC-142b.

0

2

4

6

8

10

12

14

16

18

NOAA VM 1999 VM 2011 TEAP

ODP-Weighted Emissions (kt/yr)

HCFC-142b

HCFC-141b

HCFC-124

HCFC-123

HCFC-22

7
Chapter 3: UPDATES TO AHEF OZONE CALCULATIONS

The AHEF’s ozone module (known as the “Ozone Maker”) estimates EESC and total column ozone for a 

given ODS emissions profile. This chapter presents a description of the methodology and updates in 

estimating the EESC and total column ozone estimates to reflect the state-of-the-science, and outlines 

the impacts of these changes. 

The Ozone Maker calculates the annual total ozone column for a series of latitude bands for a given 

ODS emissions profile, where each ODS emissions profile represents a specific ODS policy scenario.8 

This is calculated by applying the following systematic steps: 

• Step 1. “Emit” the ODS emissions into the atmosphere and add these emissions to the

stratospheric ODS concentration, assuming a three year lag for the emissions to reach the

stratosphere. These steps are repeated from 1950 to 2100.

• Step 2. Calculate the equivalent effective stratospheric chlorine (EESC) based on the

stratospheric ODS concentrations. These steps are repeated from 1950 to 2100.

• Step 3. Calculate total column ozone by latitude band and year for years 1978 to 2100 based

on the EESC using linear regression.

• Step 4. Apply assumptions to total column ozone column to ensure the projections do not

exceed 1979–1980 total column ozone amounts (i.e., “superabundance” of ozone) nor are

below 100 Dobson units (DU).9

These calculations require quantified information regarding specific characteristics of each ODS (e.g., 

atmospheric lifetime, atmospheric concentration, EESC). The WMO’s Scientific Assessment of Ozone 

Depletion: 2010—which represented the most up-to-date understanding of ozone depletion at this 

writing—provides minor to significant updates of these characteristics. This section describes the 

incorporation of those updates into the AHEF (WMO 2011). In addition, parts of the EESC and ozone

calculations in the AHEF were also updated, as described in further detail below. 

Updates to EESC Inputs and Impacts on Model Estimation

The methodology developed in the mid-1990s continues to be the appropriate approach for calculating 

EESC in the AHEF ozone module, albeit updated to reflect current conditions. The estimate of each 

ODS species’ concentration (i.e., ODS_CON) for a given year is as follows:

ODS_CON(i,j) = exp (-1/τI ) * ODS_CONi, j-1 + (1-exp(-1/ τ i)) * τ i *ODSi , j * Fsurf

where: 

i is the ODS species 

j is the year 

ODS_CONi,j-1 is the atmospheric concentration of the ODS species i of the previous year j-1 

τi is the atmospheric lifetime of species i10

exp (-1/τi) is the proportion of the species i remaining after 1 year

8 Because 90% of the total ozone column is in the stratosphere, most of the ozone changes are also located in the 

stratosphere (EPA 2001). 9 The average of two years, 1979 and 1980, is used to account for the effects of the quasi-biennial oscillation (QBO).

10 The atmospheric lifetime of a species is the time required for its initial concentration to decay to 1/e of its initial 

value.

8
ODSi,j is the global emission estimate for ODS species i during year j 

Fsurf is a factor that represents a general decrease of ODS mixing ratios with altitude above the 

tropopause

This equation sums the concentration of the ODS species remaining in the atmosphere from the 

previous year and the concentration of the newly emitted ODS species. A three-year lag is assumed 

from the time ODS species are emitted to the time they reach the stratosphere. 

The annual EESC contribution of each ODS species is calculated by multiplying ODS_CON(i,j) by a 

stratospheric chlorine/bromine release factor and the number of reactive moieties associated with the 

ODS species (based on the fractional release rates). If the species is a brominated compound then the 

product is multiplied by an additional factor (alpha) that represents the impact of bromine compared 

with chlorine in destroying stratospheric ozone. All EESC contributions are then summed for a global, 

annual EESC estimate. 

As noted above, WMO (2011) provides updated values for some input parameters for EESC, including 

atmospheric lifetimes, the stratospheric chlorine/bromine release factors, the conversion factor 

(kt/ppt)11, Fsurf factor, and the alpha factor. The AHEF was updated to incorporate each of these new 

values, which are shown in Table D.1 in Appendix D. In addition, the Ozone Maker module was 

updated to include emissions of Halon 1202 and Halon 2402, two ODS that were previously excluded 

from the model. The updates that affect the estimates of total EESC are as follows (using the WMO 

(2011) A1 Baseline emission profile as presented in Chapter 2): 

• The updates to the conversion factor (kt/ppt) slightly decreased the EESC associated with CFC11, CFC-12, carbon tetrachloride (CCl4), and methyl bromide (CH3Br).12 The changes in the

alpha factor (from 55 to 60) slightly increased the bromine contribution to total EESC. The

introduction of the Fsurf factor increases the estimated total EESC from 1990 to 2100 by

approximately 9 percent. However, there are no noticeable differences when comparing the

estimates of total column ozone.

• The changes in the atmospheric lifetime reduced the contribution of the EESC associated with

CCl4, methyl chloride (CH3Cl), and CH3Br to total EESC and increased the contribution of the

EESC associated with CFCs and Halon 1202 and 1211 (see Figure 6). Overall, the change in

lifetime reduced the total EESC by approximately 23 percent, although this change will vary

based on the emissions policy scenario that is modeled; these results are based on a policy

scenario that includes all amendments and adjustments to the Montreal Protocol through the

2007 Montreal Adjustment (i.e., the WMO (2011) A1 Baseline scenario), as described further

in the next chapter.

11 The conversion factor was updated to reflect our current understanding of the mass of our atmosphere (i.e., 

5.148*1018 kg). 12 The previous estimates were provided by the UNEP (1989) and have been updated in the interim.

9
Figure 6: Contribution to total EESC by ODS species summed from 1950 to 2100 (left figure 

illustrates percent contribution using previous lifetimes; right figure illustrates percent 

contribution using revised lifetimes)13

The changes in the stratospheric release factors significantly reduced the estimated total EESC; 

however, it was the differences in the slope of the estimated EESC from 1980 to 1990 (which is used to 

scale the total column ozone) that had the greatest impact on the total column ozone estimates. These 

factor updates reduced the total column ozone loss after 1995 and simulated an earlier return to 1980 

baseline conditions (see Figure 7). 

13 Halon 1202 and Halon 2402 are not included in this figure as the previous version of the OzoneMaker did not 

include these species; thus, their associated stratospheric release factor was zero (i.e., the algorithms for Halon 

1202 and Halon 2402 are not fully functional until the next step updating the stratospheric release factor). CFC115 contribution is not included as it is extremely small: 0.03% when using previous lifetimes and 0.1% when 

using the updated lifetimes.

10
Figure 7: Comparison of total EESC and total column ozone using the previous and updated 

stratospheric release factors (40°N–50° North)14

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WMO (2011) A1 Baseline with previous stratospheric release factors

Note: Circle markers indicate the maximum (EESC) and minimum (column ozone) values.

14 The total column ozone is estimated with the updates to the ozone calculations as discussed in Section 3.2.

11
Box 3: Climate Change Impacts on Ozone

As discussed in the WMO 2010 report, 

potential changes in climate may lead to 

changes in atmospheric circulation and 

chemistry that affect ozone recovery, e.g.:

 Cooling of the stratosphere may cause

ozone levels to increase in the middle to

upper stratosphere at low- and midlatitudes.

 Accelerating the Brewer-Dobson

circulation could lead to a decrease in

column ozone in the tropics and

increases elsewhere.

 Increasing the transport of ozone from

the stratosphere to the troposphere.

Updates to Ozone Calculations and Impacts on Model Estimation

Under the assumption that EESC concentrations will continue to drive the changes in stratospheric 

ozone concentrations, the calculation of total column ozone as a function of EESC, latitude, and month 

uses the following scaling equation which is identical to that used in the WMO 1998 report (WMO 

1999):

OO3(yyyyyyyy, ll ll, mmmmmm) − OO3(1980, ll ll, mmmmmm) = AA(ll ll, mmmmmm)

BB [EEEEEEEE(yyyyyyyy, ll ll, mmmmmm) − EEEEEEEE(1980,ll ll, mmmmmm)]

where: 

O3 is total column ozone (in Dobson units [DU])

A is the ozone trend from 1980 to 1990 by latitude and month (e.g., DU per decade)

B is the global EESC trend during the same period (e.g., in ppb per decade) 

The coefficient A was based on data from measurements obtained by the Total Ozone Mapping 

Spectrometer (TOMS) version 7.15 The ozone concentrations in 1980 and the ozone trend from 1980 

to 1990 used to derive the A coefficients are presented in Tables D.2 and D.3 in Appendix D (these 

values have been updated to reflect the state-of-the-science). The coefficient B was found to be 438

parts per trillion per volume (ppt) per decade using the methodology above to estimate EESC under 

the WMO (2011) A1 Baseline scenario. Further, the B coefficient is now calculated for each AHEF 

simulation based on the EESC estimated specifically from a given emissions profile. This linear 

relationship described by the scaling equation above is considered to be reasonable for mid-latitudes 

which experience relatively small ozone changes, unlike the Antarctic where an EESC threshold leads 

to non-linear ozone responses (WMO 1999). For use in AHEF, total column ozone values are 

restrained from dropping below 100 DU, given this is far outside the range of any expected future midlatitude values, or exceeding the 1979–1980 baseline values. 

The WMO 1998 report was used for this update because it was the last of the WMO reports to provide 

a simple approach in equating EESC to stratospheric ozone. The WMO 2002, 2006, and 2010 reports 

use more complicated models to calculate ozone concentrations that introduce additional factors into 

the calculation (e.g., interactions of tropospheric and 

stratospheric chemistry with climate-driven changes 

to temperatures and global circulation patterns, 

please see Box 3). 

A major advantage of using the simple linear model 

described here for a policy model is that the effects of 

different individual ODS species can be compared on 

a common basis (the EESC) and summed to give the 

total effect. This linear superposition allows 

estimation of the fraction of the total O3 depletion 

(and related health effects) that is directly

attributable to the emissions of any individual ODS 

species. This allows for a systematic understanding 

of the relationship between reducing an ODS species 

as dictated by a potential policy scenario and the 

15 McPeters et al. (1996) provided the TOMS data. Dr. Sasha Madronich, a lead author of WMO 1998 report, 

provided these data for use in the AHEF.

12
impact on total column ozone, and this type of first-order understanding helps inform policymakers.

By contrast, in a fully coupled chemistry-climate model (e.g. WMO 2002, 2006, 2010) each ODS 

emission profile would have to be considered in the context of all of the other ODS emission profiles, 

and the individual species effect would be much more difficult to isolate.16 In addition and as 

importantly, each fully coupled chemistry-climate model generally requires significant time and 

resources to run a simulation for each ODS emissions profile. Conversely, the linear model described 

here provides a means for efficiently comparing relative health effects across ODS emissions profiles

(policy scenarios). 

The updates to estimating the total column ozone, including updating the emission profile from 

VM1999 to WMO (2011) A1 Baseline, affect the predictions by (see Figure 8 below): 

• Estimating a slightly closer alignment of the 1980 total column ozone amounts with satellite

observations (e.g., total column ozone is estimated to be about 350 DU for the 40°N–50°N

latitude band); and

• Reducing total column ozone loss in the 1990s by approximately 3 percent (e.g., loss is

reduced by about 10 DU for the 40°N–50°N latitude band).

The ozone updates did not significantly affect the anticipated recovery of ozone to 1979–1980 levels 

by 2040. 

Figure 8: Comparison of total column ozone estimates using previous and updated ozone 

calculations (40–50° N)

320

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Previous ozone calculation (VM1999)

Updated ozone calculation (VM1999)

Updated ozone calculation (WMO (2011) A1 Baseline)

Note: Circle markers indicate the minimum column ozone values.

16 This methodology incorporates some simplifications. For example, it does not consider how climatic changes in 

the atmosphere may affect the relationship between EESC and ozone (WMO 1999). Though a more complicated 

chemistry-climate model might capture some of these changes, the methodology described here is transparent, is 

calibrated with historically observed ozone and EESC changes, and (importantly in the context of the AHEF) it 

allows, via linear superposition, separation and evaluation of the impacts of each individual ODS compound.

13
Chapter 4: RESULTS OF UPDATES

This chapter investigates the net result of the updates to EESC and ozone calculations, as presented in 

Chapter 2, as well as the result of switching to the new WMO (2011) A1 Baseline emission profile as 

described in Chapter 3. The following AHEF outputs are systematically compared using VM-based 

simulations and the new WMO-based simulations:

• Estimated EESC: The Ozone Maker module estimates the total EESC by year for each ODS

emissions profile representing a given ODS policy scenario (see section entitled “Comparison

of EESC” for a description of these calculations). A comparison was conducted for two

purposes: (1) to consider how the AHEF calculations of EESC compared with that estimated

across WMO reports; and (2) to consider how the EESC estimates differ between those derived

with the AHEF and those provided in the WMO 2010 assessment.

• Estimated total column ozone: After calculating EESC, the Ozone Maker module estimates

the total column ozone as a function of year and latitude-band (see section entitled

“Comparison of Ozone” for a description of these calculations). Predictions of total column

ozone for 1980 through 2100 were compared for the VM1999 and WMO (2011) A1 Baseline

simulations.

• Estimated health benefits: As a last step in the analysis, human health benefits were

estimated for two purposes: first, to understand the implications for the level of health

benefits estimated using the WMO (2011) A1 Baseline simulation compared with the VM1999

simulation; and second, to understand the human health benefits associated with various

policy scenarios based on WMO emissions profiles. Box 4 below briefly describes the process

for estimating human health effects in the AHEF and each of the health effects estimated:

cutaneous malignant melanoma, non-melanoma skin cancer, and cataract.

The 2006 EPA peer-reviewed report, Human Health Benefits of Stratospheric Ozone Protection, 

compared the historical and projected levels of EESC—a measure of chlorine loading in the 

stratosphere—and ozone in the stratosphere under the AHEF and the World Meteorological 

Organization’s (WMO) Scientific Assessment of Ozone Depletion, 1998 (WMO 1999). The 2006 EPA 

report used an emissions profile representing the changes in ODS emissions through the Montreal 

Amendments of 1997.

This effort builds on the 2006 report by also comparing VM-derived stratospheric ozone 

concentrations under an emissions profile representing the 1987 Montreal Protocol and all 

adjustments through 2007, and the concentrations produced using the emissions profile outlined in 

the WMO Scientific Assessment of Ozone Depletion, 2010 (WMO 2011). 

Specifically, the emissions simulated for each species, the trends in stratospheric ozone levels for the 

northern mid-latitudes (40°N–50°N) as well as associated EESC values were examined from baseline 

ozone conditions through recovery as projected by the VM1999 and the WMO (2011) A1 Baseline 

scenarios. In addition, updated health benefits associated with WMO policy scenarios were 

determined. Results are presented below.

14
Box 4: Estimating Human Health Effects in the AHEF

Each health effects module in the AHEF determines the change in incidence that will occur based on a 

relative change in UV dosage (i.e., the number of health effect cases that occur comparing a scenario 

case to the 1979–1980 baseline conditions). The AHEF assumes that sun exposure behavior remains 

the same in the scenario and baseline, unless otherwise modeled. While the health effects module 

calculates baseline incidence uniformly across population groups, it uses updated biological 

amplification factors (BAFs) to investigate the health effect risk by skin type and sex. The health effects 

module uses the following equation to estimate the change in the incidence for a health effect for each 

U.S. County:

Health Effect Incidence=(UVexp)(BAFByPopGroup)(BaselineIncidenceByPopGroup,Year)(PopulationByPopGroup,Year) 

where: Health Effect Incidence is the increase in incidence from scenario to baseline, UVexp is the 

cumulative percentage increase in UV exposure, BAFByPopGroup is the biological amplification factor for 

the health effect as a function of population group (skin type and sex), BaselineIncidenceByPopGroup,Year is 

the baseline incidence estimates of the health effect for each population and cohort group, and 

PopulationByPopGroup,Year is the population for each population group by year and age. Additional detail is 

available in the U.S. EPA (2006) and U.S. EPA (2010) reports, including discussions of uncertainty. 

Each of the human health effects estimated by the AHEF is briefly described below. 

Cutaneous Malignant Melanoma (CMM) Incidence Rates. CMM is a potentially life-threatening 

disease in which malignant (cancer) cells form in the skin cells called melanocytes, found in the lower 

part of the epidermis. A limited set of data on CMM incidence was extracted from the Surveillance, 

Epidemiology, and End Results (SEER) Program, based within the Cancer Control Research Program at 

the National Cancer Institute (NCI). This data set was aggregated into 18 age groups by sex, race (all 

races, light-skinned, and darker-skinned), and the three latitudinal U.S. regions.

Cutaneous Malignant Melanoma (CMM) Mortality Rates. Baseline CMM mortality data for the years 

1950 through 1984 were obtained from a EPA/NCI data set, which reports deaths from CMM in 

individuals for 18 age groups, by sex and race, covering every county in the United States.

Non-Melanoma Skin Cancer (NMSC) Incidence Rates. Basal cell carcinoma (BCC) and squamous 

cell carcinoma (SCC) are both forms of NMSC. BCC and SCC cancers originate from cells of the outer 

layer of the skin (called the epidermis) and rarely spread to other parts of the body. The incidence 

rates by age, region, and sex were developed by U.S. EPA (1987) and Fears and Scotto (1983), based 

on a nationwide survey in eight cities across the United States from 1977 to 1978. 

Non-Melanoma Skin Cancer (NMSC) Mortality Rates. The baseline mortality data by county for BCC 

and SCC were obtained from the EPA/NCI data set. The number of deaths included in this data set is 

somewhat uncertain, due to ambiguities in the reporting and recording of information on death 

certificates.

Cataract Incidence Rates. Cataract is a clouding of the eye’s naturally clear lens, which can cause 

vision impairment and blindness. Age-related cataract has a number of potential causes, but lifelong 

exposure to ultraviolet radiation from the sun plays a significant role. The cataract baseline incidence 

estimates are derived from National Health and Nutrition Examination Study (NHANES) data. The 

study consists of 2,225 subjects between the ages of 45 and 74 at 35 different locations across the 

United States Incidence estimates are stratified by location, based on the three latitudinal bands (20–

30°N, 30–40°N, and 40–50°N). Factors included skin type, sex, and population data (U.S. EPA 2010). 

For additional methodological detail, please see prior AHEF peer-reviewed reports EPA (2010) and EPA 

(2006).

15
Comparison of EESC 

EESC estimates were compared using the AHEFderived emissions profile and the WMO reports (see 

Figure 9). The EESC trend lines are relatively 

similar for the VM-derived EESC and WMO 1998, 

2002, and 2006. Likewise, the EESC predicted by 

the AHEF and WMO 2010 assessment for the WMO 

(2011) A1 Baseline scenario are similar and

dramatically lower than all of the previous WMO

assessments. This is attributable to the fact that the 

WMO 2010 assessment implemented a number of 

changes to the modeling of the fundamental 

properties of ODS. 

The WMO 2010 assessment substantially revised 

the halogen fractional release values based on new 

research presented by Newman et al. (2007). That 

study used the National Aeronautics and Space 

Administration (NASA) ER-2 field campaign 

observations to estimate fractional release values 

using a method that accounts for the age-of-air.17

This new methodology has a significant impact on 

the fractional release values of CFC-12, HCFC-22, 

CCl4 and Halon-1211. This revised methodology has 

been incorporated into the AHEF, and estimates of 

EESC compare well with those from the WMO 2010 

assessment (see Chapter 2 for more discussion). 

Figure 9 demonstrates that the algorithm now used to calculate EESC in the AHEF is consistent with 

the WMO 2010 assessment values that utilize observed values from 1980–1990. 

17 This methodology is applied to all ODS except HCFC-141b and HCFC-142b, which are estimated using the 

methodology outlined in WMO (2007). 

Box 5: EESC Estimates

Factors that influence EESC estimates 

include the estimated ODS emissions, the 

degree of dissociation of each ODS species, 

and the rate of transport to the stratosphere. 

In the estimation of ODS emissions alone, 

significant opportunity for variation exists. 

For example, the VM-based emissions profile 

estimates annual ODS emissions by 

generating an annual emissions profile for 

each ODS end use, by chemical, for all ODSconsuming countries. Conversely, WMO 

1998 (and WMO 2010) estimates of 

emissions are derived from atmospheric 

mixing ratio observations and an 

understanding of chemical lifetimes. WMO 

1998 future projections are based on 

emission functions acting on the banks of 

material yet-to-be emitted from end-use 

categories with similar emissions patterns. 

The WMO 1998 analysis assumes that the 

banks by end-use categories are replenished 

by sales, where sales are based on future 

production and consumption estimates. 

16
Figure 9: Comparison of VM-based and WMO EESC Estimates

Note: Circle markers identify peak EESC.

Sources: WMO 1999; WMO 2003; WMO 2007; WMO 2011. All EESC estimates are based on the baseline scenario. The VM1999 simulation is based on the Montreal Protocol and all 

adjustments through 2007.

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WMO (1999)

WMO (2003)

WMO (2007)

17
Comparison of Ozone

The AHEF-derived total column ozone (VM1999) was compared with the modeling reported in Figure 

3-6 of the WMO 2010 assessment report and Figure 11-14 of the WMO 1998 assessment report as 

illustrated in Figure 10 below.

18,19,20 In addition, the WMO (2011) A1 Baseline AHEF-derived 

estimates of total column ozone are provided. The ozone assessments conducted by the WMO in 2002 

and 2006 do not provide total column ozone associated with their EESC projections; therefore, direct 

comparison was not possible.21 The WMO 1998 values are provided as a record of WMO estimates 

made during a similar time period of the VM-derived total column ozone and hence rely on similar 

scientific understanding as utilized in the previous AHEF calculations. However, the WMO 1998 values 

do not account for additional ODS control measures implemented after 1997. 

The WMO 1998 projections are based on annually- and monthly-averaged stratospheric ozone 

concentrations for different latitudes as measured by NASA's Total Ozone Mapping Spectrometer 

(TOMS) on the Nimbus-7 satellite. The WMO (2011) projections presented here represent the mean 

total column ozone predicted by 17 multi-model chemistry-climate models (CCM).22 Unlike the AHEF, 

these CCMs account for the impact of climate change on stratospheric ozone concentrations. The WMO 

2010 assessment provides a lower and higher limit of the 95 percent prediction interval around the 

mean multi-model ensemble estimate to account for the spread among the 17 CCMs. 

As illustrated in Figure 10, both the AHEF- and WMO-based estimates indicate that stratospheric 

ozone concentrations reached minimum levels in the late 1990s. The U.S. Global Change Research 

Program similarly projected that concentrations of ODS in the atmosphere would peak before the year 

2000 (USGCRP 1998). Figure 10 also shows that the AHEF-based estimates and those from the WMO 

1998 Assessment are in agreement regarding the speed of ozone recovery, both projecting full 

recovery to 1980 levels around 2045 for the northern mid-latitudes.23 The WMO 2010 assessment 

ensemble model average predicts recovery to 1980 levels much sooner, in approximately 2020, while 

the lower bound of the 95 percent prediction interval about the mean multi-model ensemble estimates 

recovery at about 2030 (represented by the lower bound of the model ensemble average on Figure 

10). The upper bound of the model ensemble average in Figure 10 is not readily comparable to VMbased estimates or to observed column ozone values. 

18 This comparison provides the total column ozone levels only for the Montreal Adjustment policy scenarios that 

included predictions of chlorine and bromine levels in the atmosphere.

19 Trend lines provided in Figure 9 and Figure 10 were extrapolated from a hard-copy analysis of available figures. 20 Differences in the specification of northern mid-latitude bands may affect this comparison. AHEF values 

represent total column ozone across the 40°N to 50°N latitude band, WMO 1998 values are provided at 45°N 

latitude, and WMO 2010 values are provided for the 35°N to 60°N latitude band. 21 Further, the WMO 2002 and 2006 assessments incorporate revised assumptions regarding HCFC production 

levels. Thus, the WMO 2002 and 2006 EESC projections are lower than the WMO 1998 projections. Without the 

revised ozone concentration projections associated with this lower EESC scenario, it is unclear how the WMO 2002 

and 2006 ozone concentration projections compare with AHEF in terms of ozone concentration predictions and 

how these changes in ozone concentrations would affect incremental health effects. 22 The WMO 2010 assessment provides 1980 baseline-adjusted multi-model trend estimates of annually averaged 

total column ozone for mid-latitudes. In Figure 12, for purposes of comparison, these estimates have been adjusted 

using the data presented in Table 3-3 of the WMO 2010 report, where the baseline of annually averaged total 

column ozone in 1980 is 353 Dobson units for the northern mid-latitudes. In the WMO 2010 report, the 

Intergovernmental Panel on Climate Change (IPCC) Special Report Emission Scenarios (SRES) A1B (a moderate 

scenario) was used to project greenhouse gas emissions. The ODS concentrations were based on observations from 

a number of sources, plus the adjusted A1 scenario (termed “baseline”) as detailed in WMO (2007) Table 8-5. 23 As the purpose of the AHEF is to calculate benefits associated with reaching ozone layer recovery through ODS 

controls, the model does not allow stratospheric column ozone levels to exceed baseline conditions. In contrast, the 

WMO 2010 assessment does not cap ozone recovery at baseline levels.

18
It is important to note that the modeling simulated in the WMO 2010 assessment considers factors that 

were not available in previous modeling efforts, including changes in meteorology and chemistry 

brought about by projected increases in the concentrations of the greenhouse gases carbon dioxide, 

methane, and nitrous oxide, as described earlier in this report in Box 3. In addition, the WMO 2010 

assessment notes that natural variability, including, for example, influences of volcanic eruption and 

solar cycle variations, will likely complicate prediction of when actual recovery occurs. Regardless of 

natural variability and changing atmospheric parameters, the WMO 2010 assessment projects changes 

in the atmosphere as a result of emissions of the major greenhouse gases will hasten ozone recovery 

before the middle of the 21st century and its superrecovery thereafter. 

Figure 10: Northern Mid-Latitude Total Column Ozone Comparison (40°N–50°N)

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Model Ensemble Average: Baseline (WMO 2011)

(shading indicates spread across models)

A1: Baseline (WMO 2011 using AHEF)

VM1999

A1: Baseline (WMO 1999)

A3: Maximum Production (WMO 1999)

Sources: WMO 1999; WMO 2011.

Finally, the AHEF-derived total column ozone based on the WMO (2011) A1 Baseline emissions profile 

demonstrates less reduction in ozone concentration compared with the previous estimate used by the 

AHEF (VM1999). In addition, the AHEF-based estimates predict a minimum ozone concentration of 

approximately 320 and 335 Dobson units (DU) for the northern mid-latitudes, while the WMO 1998 

estimates indicate a minimum of approximately 335 DU and the WMO 2010 ensemble model average 

estimates suggest an even higher minimum of approximately 345 DU. The primary reasons for the 

difference between the minima predicted by the AHEF-based estimates are the revised global emission

factors, and the updated input parameters and methodology used to estimate EESC and ozone 

concentrations.

Comparison of Health Benefits

In order to understand the implications for human health effects associated with the model updates 

described in Chapters 2 and 3, this analysis used the AHEF to simulate health benefits using the 

previous version of the AHEF (including the VM-based emission profile referred to as VM1999) and 

the version of the AHEF updated as described in this report (including the new WMO (2011) A1 

Baseline emission profile). The health benefits modeled are those associated with the Montreal 

Protocol as adjusted and amended through the 2007 Montreal Adjustment (“2007 Montreal 

Adjustment”), as compared to a no policy controls scenario and as compared to the 1987 Montreal 

19
Protocol. Three categories of human health effects were compared: cataract incidence, 

cutaneous malignant melanoma (CMM) incidence and mortality, and non-melanoma skin cancer 

(NMSC) incidence and mortality, as presented in Table 2. 

The updated WMO-based results show slightly fewer skin cancer mortalities and incidence avoided 

than the previous VM-based results, when comparing the “2007 Montreal Adjustment” to “No Policy 

Controls.” These results reflect both the smaller reduction in total column ozone associated with the 

updates to the AHEF as described in this report, as well as differences in the modeling of the “No 

Controls” scenario between the previous VM-based AHEF and the updated WMO-based AHEF. When 

comparing the “2007 Montreal Adjustment” to the “1987 Montreal Protocol,” the updated WMO-based 

results are similar to the previous VM-based results in terms of skin cancer mortalities and incidence 

avoided. Appendix E presents the total column ozone modeled for each of these scenarios.

As shown, using the updated AHEF, when compared with a situation of no policy controls, full 

implementation of the Montreal Protocol, including its Amendments and Adjustments, is expected to 

avoid more than 280 million cases of skin cancer, approximately 1.6 million skin cancer deaths, and 

more than 45 million cases of cataract in the United States for cohort groups in birth years 1890−

2100.24

Version

Table 2: U.S. Health Benefits of the Montreal Protocol for Cohorts in Birth Years 1890−2100 

Scenarios AHEF Health Effect : Avoided Cases / Deaths 

Skin Cancer Mortality Skin Cancer Incidence Cataract 

NMSC CMM Total NMSC CMM Total Incidence

2007

Montreal 

Adjustment 

compared 

with No 

Policy 

Controls

VM1999 567,300 1,289,200 1,856,500 328,228,200 10,017,000 338,305,200 51,481,600

WMO 

(2011) 

A1 

Baseline

477,700 1,075,000 1,552,700 274,750,200 8,313,800 283,063,900 45,553,000

2007 

Montreal

Adjustment 

compared 

with 1987 

Montreal 

Protocol

VM1999 264,000 586,900 850,900 150,752,900 4,522,600 155,275,500 24,607,200

WMO 

(2011) 

A1 

Baseline

264,200 587,700 851,900 150,716,600 4,520,000 155,236,500 24,675,000

Totals may not sum due to independent rounding. 

VM1999 reflects the AHEF model used prior to the updates made as described in this report; WMO (2011) A1 Baseline 

reflects the updates made to the AHEF as described in this report. 

24 The AHEF generates results for five-year cohorts for birth years 1890 through 2100. For more detail, please see 

U.S. EPA (2006). 

20
Chapter 5: FUTURE MODELING AND RESEARCH

This chapter describes both how the updated AHEF can be used for future analyses, as well as 

opportunities for further research and updates to the AHEF model.

Emissions Profiles for Future ODS Control Policy Scenarios

The AHEF is used to model human health benefits associated with ODS control policy scenarios both in 

the United States and the rest of the world. Changes in human health benefits are simulated by 

comparing two global emissions profiles—one representing the baseline (typically emissions 

associated with implementation of the Montreal Protocol and its amendments and adjustments 

through the 2007 Montreal Adjustment , which is provided by the WMO (2011) A1 baseline in the 

updated AHEF) and one representing the policy scenario. As such, the driver of the change in human 

health benefits is the delta between the baseline and policy scenario emission profiles.

The following approaches will be used to develop emissions profiles associated with future ODS 

control policy scenarios in the United States and the rest of the world. 

• Future U.S. ODS Policy Scenarios—EPA’s Vintaging Model will be used to estimate changes in

U.S. emissions associated with a given future policy scenario.25,26 The change in U.S. emissions

associated with the future policy scenario will be added to global baseline emissions to

generate the global emissions profile associated with the policy scenario, as illustrated in the

equation below:

Global ODS Emissions (WMO (2011) A1 Baseline) + Change in U.S. Emissions (Using VM) = Scenario 

Global ODS Emissions (New U.S. Policy)

• Future Rest-of-World ODS Policy Scenarios—For future policy scenarios in the rest of the

world (i.e., non-U.S.), available data sources will be reviewed to determine the best available

data for estimating changes in non-U.S. emissions. These sources might include country- or

region-specific emissions reports or modeling, data reported as part of HCFC phaseout

management plans in developing countries, or consumption data reported under Article 7 of

the Montreal Protocol (scaled using consumption-to-emissions factors). The change in rest-ofworld emissions associated with the future policy scenario will be added to global baseline

emissions to generate the global emissions profile associated with the policy scenario, as

illustrated in the equation below:

Global ODS Emissions (WMO (2011) A1 Baseline) + Change in Rest-of-World Emissions (Using 

Available Data) = Scenario Global ODS Emissions (New Rest-of-World Policy)

In both cases, the AHEF will then be used to simulate the change in health effects associated with the 

global scenario emissions as compared with the global baseline emissions. 

25 Note that the WMO (2011) A1 baseline does not provide country-specific data that would enable modeling at the 

country-level. 26 The Vintaging Model is regularly updated. Appendix F provides the changes that have occurred in the Vintaging 

Model from the 1999 version through 2012.

21
Future AHEF Updates

The AHEF is updated regularly to reflect new information and science. While this round of updates 

incorporates new parameters for ODS characteristics and an updated global emissions profile, these 

values are subject to future research and updates. If new parameters or new global emission datasets 

become available in the future, these changes should be considered for the AHEF. In addition, future 

updates should take into account the WMO Ozone Assessment schedule to align efforts with the stateof-the-science.

22
REFERENCES

CCSP (2008). Trends in Emissions of Ozone-Depleting Substances, Ozone Layer Recovery, and 

Implications for Ultraviolet Radiation Exposure. A Report by the U.S. Climate Change Science Program 

and the Subcommittee on Global Change Research. [Ravishankara, A.R., M.J. Kurylo, and C.A. Ennis 

(eds.)]. Department of Commerce, NOAA’s National Climatic Data Center, Asheville, NC, 240 pp.

Hiller, R., R. Sperduto, and F. Ederer (1983). "Epidemologic associations with cataracts in the 1971-

1972 National Health and Nutrition Examination Survey," American Journal of Epidemiology, 118, 239-

249.

ICF (2011) AHEF Global ODS Emission Estimates Memorandum. Deliverable under EPA Contract # EPW-10-031, Task Order 3, Task 2.

IPCC/TEAP (2005) Special Report on Safeguarding the Ozone and the Global Climate System: Issues 

Related to Hydrofluorocarbons and Perfluorocarbons. Available online at 

<http://www.ipcc.ch/pdf/special-reports/sroc/sroc_full.pdf>.

IPCC (Intergovernmental Panel on Climate Change) (2001), Climate Change 2001: The Scientific Basis.

Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on

Climate Change. Edited by J.T. Houghton, Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. 

Maskell, and C.A. Johnson. Cambridge, UK.

McPeters, R.D., S.M. Hollandsworth, L.E. Flynn, J.R. Herman, and C.J. Seftor (1996). Long-term ozone 

trends derived from the 16-year combined Nimbus 7/Meteor 3 TOMS version 7 record, Geo Phys. Res. 

Lett., 23, 3699-3702.

NASA (National Aeronautics and Space Administration) /EPA (Environmental Protection Agency) 

(2001), Human Health Effects of Ozone Depletion From Stratospheric Aircraft. NASA/CR-2001-211160, 

September 2001.

Newman, P.A., J.S. Daniel, D.W. Waugh, and E.R. Nash, (2007), A new formulation of equivalent effective 

stratospheric chlorine (EESC), Atmos. Chem. Phys., 7 (17), 4537-4552, doi: 10.5194/acp-7-4537-2007.

Pitcher, H.M., and J.D. Longstreth (1991), "Melanoma mortality and exposure to ultraviolet radiation: 

An empirical relationship," Environment International 17:7-21.

Ries, L.A.G., C.L. Kosary, B.F. Hankey, B.A. Miller, and B.K. Edwards (Eds.) (1999), SEER Cancer Statistics 

Review, 1973-1996, National Cancer Institute, Bethesda, MD.

Sasaki H, Sakamoto Y, Schnider C et al. (2009),”Exposure to the Eye as a Function of Solar Altitude,” 

Optom Vis Sci. 86:e-abstract 95883.

Scotto, J., H. Pitcher, and J.A.H. Lee (1991), "Indications of future decreasing trends in skin-melanoma 

mortality among whites in the United States," Int. J. Cancer 49:490-497.

UNEP (1989). Open-ended working group of the parties to the Montreal Protocol. First session of the 

second meeting. Geneva, 13–17 November 1989. 

http://ozone.unep.org/Meeting_Documents/oewg/2oewg/2oewg1-4.e.doc

U.S. EPA (2001), Human Health Effects of Ozone Depletion from Stratospheric Aircraft, United States 

Environmental Protection Agency, Washington, D.C. 

23
U.S. EPA (2006), Human Health Benefits of Stratospheric Ozone Protection, United States Environmental 

Protection Agency, Washington, D.C. Available online at: 

http://www.epa.gov/ozone/science/effects/AHEFApr2006.pdf

U.S. EPA (2010), Protecting the Ozone Layer Protects Eyesight: A Report on the Cataract Incidence in the 

United States using the Atmospheric and Health Effects Framework, United States Environmental 

Protection Agency, Washington, D.C. Available online at: 

http://www.epa.gov/ozone/science/effects/AHEFCataractReport.pdf

U.S. EPA (2012), U.S. Vintaging Model (VM IO file_v4.4_03.23.12). March 23, 2012.

U.S. EPA (2011). Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990 – 2009; Annex 3. 

Available online at <http://epa.gov/climatechange/emissions/usinventoryreport.html>.

USGCRP (US Global Research Program) (1998), Depletion and Recovery of the Ozone Layer: An Update 

on Scientific Understanding. USGCRP Seminar, 23 September 1998. 

Velders et al. (2009). The large contribution of projected HFC emissions to future climate forcing. 

Available online at < http://www.pnas.org/content/early/2009/06/19/0902817106.full.pdf+html>.

Velders et al. (2014). Uncertainty analysis of projections of ozone-depleting substances. Atmos. Chem. 

Phys., 14, 2757-2776.

WMO (World Meteorological Organization) (1999), Scientific Assessment of Ozone Depletion: 1998. 

World Meteorological Organization Global Ozone Research and Monitoring Project – Report No. 44, 

732 pp., Geneva, Switzerland.

WMO (2003), Scientific Assessment of Ozone Depletion: 2002. WMO Global Ozone Research and

Monitoring Project – Report No. 47, 498 pp., Geneva, Switzerland. 

WMO (2007), Scientific Assessment of Ozone Depletion: 2006. World Meteorological Organization Global 

Ozone Research and Monitoring Project – Report No. 50, 572 pp., Geneva, Switzerland. 

WMO (2011), Scientific Assessment of Ozone Depletion: 2010. Global Ozone Research and Monitoring 

Project – Report No. 52, 516pp., Geneva, Switzerland.

WMO (2014), Assessment for Decision-Makers: Scientific Assessment of Ozone Depletion: 2014. Global 

Ozone Research and Monitoring Project—Report No. 56, 88 pp., Geneva, Switzerland, 2014

24
APPENDIX A: POTENTIAL GLOBAL ODS AND ODS

SUBSTITUTE DATA SOURCES

ICF reviewed potential data sets of global ODS or ODS substitute emissions or consumption estimates. 

The table below summarizes this research.

Table A.1: Potential Data Sources

Source Data Description

IPCC/TEAP Special Report ODS emissions

Velders et al. ODS emissions

UNEP TOC Reports ODS emissions

WMO 2010 Scientific Assessment ODS emissions

IPCC SRES ODS emissions

SAP 2.4 ODS emissions

U.S. Proposed MP Adjustment 

Analysis

HCFC emissions

UN Global Emissions Inventory 

Activity v1

CFC-11, CFC-12, HCFC-22, & MCF 

emissions up to 2000

UNEP Article 7 Data ODS consumption

SRI Chemical Economics Handbook ODS production and consumption

AFEAS ODS production and sales

ICIS Fluorocarbon Profile Fluorocarbon production capacity

EDGAR ODS sub and HCFC-141 emissions

EPA GHG Reporting Program ODS sub production

EPA Global Emissions Report ODS sub emissions

UNFCCC ODS sub emissions

25
APPENDIX B: EMISSION PROFILE ESTIMATES FROM 1950 THROUGH 2100

The emissions profile estimates emissions under the agreement of the Montreal Protocol and the adjustments thereafter through 2007. The global 

emissions for each species based on the WMO (2011) A1 Baseline scenario are provided in Table B.1 in 5-year increments (this is a condensed version of the 

annual global emissions that are used to drive AHEF).

 Table B.1: Emissions Profile in 5-year increments (million kilograms/year)

CFC-11 CFC-12 CFC-113 CFC-114 CFC-115 Halon

1211

Halon 

1301

Halon 

2402

CCl4 CH3CCl3 HCFC-22 HCFC-123 HCFC-124 HCFC-141b HCFC-142b CH3Cl CH3Br Halon

1202

1950 22.8574 139.9813 31.0164 45.4441 0.0000 0.0000 0.0000 0.0 953.7000 0.0000 14.1000 0.0000 0.0000 0.0000 0.0000 0.0000 158.8000 0.0

1955 24.6074 50.3490 3.2329 7.5371 0.0000 0.0000 0.0000 0.2 85.0000 3.5132 2 .9843 0.0000 0.0000 0.0000 0.0000 4098.5213 121.2648 0.0

1960 43.3472 93.1007 6.3662 6.8138 0.0000 0.0000 0.0000 0.6 110.0000 18.3556 7.6810 0.0000 0.0000 0.0000 0.0000 4253.6327 125.8279 0.1

1965 115.7651 185.9544 12.4258 8.2557 0.4438 0.0314 0.0053 1.0 127.0000 48.1159 20 .5680 0.0000 0.0000 0.0000 0.0000 4397.8144 130.9230 0.1

1970 221.1475 321.7800 24.4944 10.0466 1.5387 0.3231 0.0432 1.5 127.0000 141.3837 43.7821 0.0000 0.0000 0.0000 0.0000 4488.8532 136.6585 0.2

1975 335.7847 442 .8850 48 .5050 15.0250 3.3970 1.3409 0.5241 2.1 127.0000 309.1173 70.7375 0.0000 0.0000 0.0000 0.819 4533.2636 143.1641 0.3

1980 274.0146 390.4361 82.8830 14.0896 5.9783 3.3922 1.8048 1.7 128.6600 521.2403 111.7820 0.0000 0.0000 0.0000 1.9403 4552.2507 150.5889 0.5

1985 342.3122 438.0398 160.1091 16.2738 9.2577 6.9592 3.9975 1.04 126.3453 558.7162 137.2363 0.0000 0.0000 0.0000 1.2584 4559.9204 159.0940 0.60

1990 267.0432 365.7519 215.5177 9.8409 10.8942 11.4968 5.1195 0.84 97.5896 627.6498 186.2219 0.0000 0.0000 0.1167 10.2377 4562.9512 168.8310 0.16

1995 121.2463 206.3803 33.3735 4.6242 7.9869 10.1091 0.3941 0.87 83.4474 181.7037 221.3669 0.0000 0.0000 41.7831 23.4046 4046.4564 174.2125 0.02

2000 94.8671 143.5285 14.0971 3.2026 3.3543 9.1399 1.2637 0.58 73.5276 22.8112 243.9201 0.0000 0.0000 58.6655 27.4412 4564.3715 159.7707 0.00

2005 76.4778 90.1100 9.5249 1.5946 0.5381 7.3251 1.9588 0.38 64.9722 6.9742 296.9958 0.0000 0.0000 43.8576 26.7501 4564.3715 146.9916 0.00

2010 63.8254 43.3557 3.9089 1.1928 0.3067 4.7718 1.7348 0.25 45.7034 6.9039 423.2003 0.0000 0.0000 59.3971 39.8256 4564.3715 138.3578 0

2015 49.3868 19.2372 0.1222 0.7043 0.2772 3.2314 1.4145 0.17 33.5419 0.0000 460.5124 0.0000 0.0000 76.7610 43.5939 4564.3715 136.3216 0

2020 38.2146 8.5356 0.0038 0.4159 0.2506 2.1883 1.1534 0.11 24.6166 0.0000 397.0638 0.0000 0.0000 81.7833 38.8861 4564.3715 136.3216 0

2025 29.5697 3.7873 0.0001 0.2456 0.2265 1.4819 0.9404 0.07 18.0662 0.0000 289.4512 0.0000 0.0000 77.4661 30.5318 4564.3715 136.3216 0

2030 22 .8805 1.6804 0.0000 0.1450 0.2048 1.0035 0.7668 0.05 13.2589 0.0000 168.7107 0.0000 0.0000 66.3265 20.9624 4564.3715 136.3216 0

2035 17.7045 0.7456 0.0000 0.0856 0.1851 0.6796 0.6252 0.03 9.7307 0.0000 68.8811 0.0000 0.0000 51.9305 12.0879 4564.3715 136.3216 0

2040 13.6994 0.3308 0.0000 0.0506 0.1673 0.4602 0.5098 0.02 7.1414 0.0000 30.0586 0.0000 0.0000 40.6567 7.0371 4564.3715 136.3216 0

2045 10.6003 0.1468 0.0000 0.0299 0.1512 0.3116 0.4157 0.01 5.2411 0.0000 11.1439 0.0000 0.0000 31.4594 3.9296 4564.3715 136.3216 0

2050 8.2023 0.0651 0.0000 0.0176 0.1367 0.2110 0.3389 0.01 3.8465 0.0000 4.1315 0.0000 0.0000 24.3427 2.1943 4564.3715 136.3216 0

2055 6.3468 0.0289 0.0000 0.0104 0.1236 0.1429 0.2764 0.01 0.0000 0.0000 1.5317 0.0000 0.0000 18.8359 1.2253 4564.3715 136.3216 0

2060 4.9110 0.0128 0.0000 0.0061 0.1117 0.0968 0.2253 0.00 0.0000 0.0000 0.5679 0.0000 0.0000 14.5748 0.6842 4564.3715 136.3216 0

2065 3.8001 0.0057 0.0000 0.0036 0.1010 0.0655 0.1837 0.00 0.0000 0.0000 0.2105 0.0000 0.0000 11.2777 0.3821 4564.3715 136.3216 0

2070 2 .9404 0.0025 0.0000 0.0021 0.0913 0.0444 0.1498 0.00 0.0000 0.0000 0.0781 0.0000 0.0000 8.7265 0.2134 4564.3715 136.3216 0

2075 2.2752 0.0011 0.0000 0.0013 0.0825 0.0301 0.1221 0.00 0.0000 0.0000 0.0289 0.0000 0.0000 6.7524 0.1191 4564.3715 136.3216 0

2080 1.7605 0.0005 0.0000 0.0007 0.0746 0.0204 0.0996 0.00 0.0000 0.0000 0.0107 0.0000 0.0000 5.2249 0.0665 4564.3715 136.3216 0

2085 1.3623 0.0002 0.0000 0.0004 0.0674 0.0138 0.0812 0.00 0.0000 0.0000 0.0040 0.0000 0.0000 4.0429 0.0371 4564.3715 136.3216 0

2090 1.0541 0.0001 0.0000 0.0003 0.0609 0.0093 0.0662 0.00 0.0000 0.0000 0.0015 0.0000 0.0000 3.1283 0.0207 4564.3715 136.3216 0

2095 0.8156 0.0000 0.0000 0.0002 0.0551 0.0063 0.0540 0.00 0.0000 0.0000 0.0005 0.0000 0.0000 2.4206 0.0116 4564.3715 136.3216 0

2100 0.6311 0.0000 0.0000 0.0001 0.0498 0.0043 0.0440 0.00 0.0000 0.0000 0.0002 0.0000 0.0000 1.8730 0.0065 4564.3715 136.3216 0

26 
APPENDIX C: COMPARISON OF EMISSION PROFILES BY

SPECIES

As discussed in Section 3.3, this appendix provides additional figures that were used to inform the 

comparison of the global ODS emissions developed through the VM-derived emissions profile and the 

WMO (2011) A1 Baseline emissions profile by ODS species.

Figure C.1. Comparison of VM-derived and WMO (2011) A1 Baseline emissions profiles by ODS 

species

0

50

100

150

200

250

300

350

400

1950 2000 2050 2100

Emissions (kt/yr)

CFC-11 VM 1999 CFC-11 WMO A1

0

100

200

300

400

500

600

1950 2000 2050 2100

Emissions (kt/yr)

CFC-12 VM 1999 CFC-12 WMO A1

0

50

100

150

200

250

1950 2000 2050 2100

Emissions (kt/yr)

CFC-113 VM 1999 CFC-113 WMO A1

0

5

10

15

20

25

1950 2000 2050 2100

Emissions (kt/yr)

CFC-114 VM 1999 CFC-114 WMO A1

27
Figure C.1. Comparison of VM-derived and WMO (2011) A1 Baseline emissions profiles by ODS

species cont.

0

2

4

6

8

10

12

1950 2000 2050 2100

Emissions (kt/yr)

CFC-115 VM 1999 CFC-115 WMO A1

0

20

40

60

80

100

120

140

160

1950 2000 2050 2100

Emissions (kt/yr)

CCl4 VM 1999 CCl4 WMO A1

0

100

200

300

400

500

600

700

1950 2000 2050 2100

Emissions (kt/yr)

CH3CCl3 VM 1999 CH3CCl3 WMO A1

0

50

100

150

200

250

300

350

400

450

500

1950 2000 2050 2100

Emissions (kt/yr)

HCFC-22 VM 1999 HCFC-22 WMO A1

0

10

20

30

40

50

60

70

80

90

1950 2000 2050 2100

Emissions (kt/yr)

HCFC-141b VM 1999 HCFC-141b WMO A1

0

5

10

15

20

25

30

35

40

45

50

1950 2000 2050 2100

Emissions (kt/yr)

HCFC-142b VM 1999 HCFC-142b WMO A1

28
Figure C.1. Comparison of VM-derived and WMO (2011) A1 Baseline emissions profiles by ODS

species cont.

0

2

4

6

8

10

12

14

16

1950 2000 2050 2100

Emissions (kt/yr)

Halon 1211 VM 1999 Halon 1211 WMO A1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1950 2000 2050 2100

Emissions (kt/yr)

Halon 1202 VM 1999 Halon 1202 WMO A1

0

1

2

3

4

5

6

7

8

9

1950 2000 2050 2100

Emissions (kt/yr)

Halon 1301 VM 1999 Halon 1301 WMO A1

0.0

0.5

1.0

1.5

2.0

2.5

1950 2000 2050 2100

Emissions (kt/yr)

Halon 2402 VM 1999 Halon 2402 WMO A1

0

20

40

60

80

100

120

140

160

180

200

1950 2000 2050 2100

Emissions (kt/yr)

CH3Br VM 1999 CH3Br WMO A1

0

1000

2000

3000

4000

5000

6000

7000

1950 2000 2050 2100

Emissions (kt/yr)

CH3Cl VM 1999 CH3Cl WMO A1

29
APPENDIX D: PARAMETERS AND COEFFICIENTS USED TO

INFORM THE EESC AND OZONE CALCULATIONS

Table D.1 details the parameters used in AHEF in estimating EESC by ODS species. The lifetime, 

stratospheric chlorine factor, and the alpha factor are updated using the estimates provided in the WMO 

2010 report. In addition, two ODS species, Halon 2402 and Halon 1202, have been added. Given the 

WMO (2011) A1 Baseline emissions profile does not include HCFC-123 and HCFC-124, the 

corresponding stratospheric chlorine release factors are not provided in WMO (2011). This 

“inactivates” these species’ contributions to total EESC. Finally, Fsurf, a parameter that effectively 

accounts for a general decrease of ODS mixing ratios with altitude above the tropopause, was defined as 

1.07 for all ODS species except CH3Br. The Fsurf of CH3Br was 1.16 (Velders, 2014). 

Since the development of this report, updated lifetimes have become available through the WMO 2014 

report and are provided in the table below for reference (see “2014 Ozone Assessment”). The WMO 

2014 assessment uses the same stratospheric chlorine release factors as used here. 

Table D.1. The parameters used for each ODS species for estimating EESC

ODS Species Lifetime (years) Stratospheric 

Chlorine Release 

Factor

Alpha Factor Number 

of 

Chlorine 

Atoms

Conversion 

Factor 

(kt/ppt)

Current Previous 2014 Ozone 

Assessment

Current Previous Current Previous

CFC-11 45 50 52 0.47 0.9 0 0 3 24.5

CFC-12 100 102 102 0.23 0.45 0 0 2 23.1

CFC-113 85 85 93 0.29 0.5 0 0 3 33.3

CFC-114 190 300 189 0.12 0.58 0 0 2 30.4

CFC-115 1020 1700 540 0.04 0.12 0 0 1 27.5

HCFC-22 11.9 12.1 12 0.13 0.315 0 0 1 15.4

HCFC-123 1.3 1.4 - NA 1 0 0 2 27.1

HCFC-124 5.9 6.1 - NA 0.4707 0 0 1 24.2

HCFC-141b 9.2 9.4 9.4 0.34 0.65 0 0 2 20.6

HCFC-142b 17.2 18.4 18 0.17 0.324 0 0 1 17.8

Halon 1301 65 65 72 0.28 0.72 60 55 0 26.5

Halon 1211 16 20 16 0.62 0.99 60 55 1 29.4

Halon 2402 20 77 28 0.65 0 120 110 0 46.3

Halon 1202 2.9 2.9 2.5 0.62 0.62 120 110 0 37.3

CH3Br 0.8 0.8 0.8 0.6 0.97 60 55 0 16.9

CCl4 26 42 26 0.56 0.95 0 0 4 27.4

CH3CCl3 5 4.9 5 0.67 0.9 0 0 3 23.7

CH3Cl 1 1.5 0.9 0.44 0.99 0 0 1 9

“Current” refers to this report with values provided by the WMO (2011) Assessment; “previous” refers to previous 

values in the AHEF.

The A coefficients by latitude and month are calculated as the product of Tables D.2 and D.3. The data in 

these tables were based on data measurements obtained by the Total Ozone Mapping Spectrometer 

(TOMS) version 7 (McPeters et al. 1996; WMO 1999), with trends derived from November 1979 to June 

1991 (just before the Mt. Pinatubo eruption which caused additional ozone perturbations).

30
Table D.2. Ozone Vertical Column (Dobson units) for 1980 by latitude band and month

Latitude

Band

(

o

N)

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

20 to 30 261 264 274 288 299 296 293 283 283 275 266 266

30 to 40 311 324 335 334 336 321 307 301 291 283 283 302

40 to 50 364 398 398 392 378 356 333 319 307 313 313 336

50 to 60 388 418 440 426 404 375 352 330 321 330 330 345

60 to 70 0 408 455 448 413 371 342 319 311 0 0 0

Table D.3. Ozone trend (% per decade) from 1980 to 1990 by latitude band and month

Latitude

Band

(

o

N)

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

20 to 30 -2.1 -1.8 -1.0 -0.5 -0.5 -1.0 -1.4 -1.3 -0.9 -0.7 -1.1 -1.7

30 to 40 -4.2 -5.1 -4.4 -2.8 -1.6 -1.5 -2.2 -2.4 -1.7 -0.6 -0.7 -2.3

40 to 50 -3.7 -5.4 -5.8 -4.7 -3.0 -2.0 -2.0 -2.5 -2.2 -1.1 -0.5 -1.5

50 to 60 -0.7 -2.6 -4.3 -4.8 -4.1 -2.9 -2.4 -2.9 -3.3 -2.5 -0.8 0.2

60 to 70 0.0 0.0 -3.2 -4.6 -4.5 -3.5 -2.7 -3.0 -3.6 -2.7 0.0 0.0

31
APPENDIX E: TOTAL COLUMN OZONE FOR MODELED

POLICY SCENARIOS

Figure E-1 presents total column ozone associated with three policy scenarios: no policy controls; the 

1987 Montreal Protocol; and the Montreal Protocol as amended and adjusted through the 2007 

Montreal Adjustment. Total column ozone is shown for two versions of the AHEF—the previous VMbased AHEF as used prior to the updates made through this report; and the updated WMO-based AHEF 

that incorporates the modeling changes described in this report. As shown, the total column ozone 

modeled for the 1987 Montreal Protocol and 2007 Montreal Adjustment are relatively similar between 

the VM-based and WMO-based versions of the AHEF; however, the no controls scenario is significantly 

different, which has implications for estimating human health benefits relative to no policy controls.

Figure E-1: Total Column Ozone Associated with No Controls, 1987 Montreal Protocol, and 2007 

Montreal Adjustment Policy Scenarios

32
APPENDIX F: EXPLANATION OF DIFFERENCES BETWEEN

VM1999 AND VM2012

This table provides a description of the major VM updates that affect the emission estimates of each 

species between VM1999 and VM2012. Future U.S. based policy scenarios would be developed using 

the latest VM.

Table F.1: Explanation of Differences between VM1999 and VM2012

Species Differences Explanation for Differences

CFC-11

Emissions continue through 2050 in 

VM4.4 (emissions end in 2039 in VM 

1999), and are lower in VM4,4

Many Ref transitions away from CFC-11 began earlier 

than 1996

CFC-12 Overall, lower emissions in VM4.4 Many Ref transitions away from CFC-12 began earlier 

than 1996

HCFC-22 Higher emissions in VM4.4 

Reflection of major uses of HCFC-22 as a CFC alternative 

(most commonly used HCFC; used in Ref, AC, and foam 

applications)

CFC-113 Latest VM phases out CFC-113 by 

1996, otherwise, relatively similar

Emissions consistent with Montreal Protocol phaseout 

schedule

CT (CCl4) VM4.4 has much lower emissions, 

which end in 1996

Emissions consistent with Montreal Protocol phaseout 

schedule and niche solvent applications of CT

MCF Similar emissions until 1996, VM4.4 

emissions end

Emissions consistent with Montreal Protocol phaseout 

schedule and niche solvent applications of MCF

CH3Cl None NA

Halon 1301

Lower emissions in VM4.4 through 

2032, Higher emissions in VM4.4 

through 2050

Critical uses of Halon 1301 for fire suppression

Halon 1211

Lower emissions in VM4.4 through 

2029, Higher emissions in VM4.4 

through 2050

Critical uses of Halon 1211 for fire suppression

CH3Br Not included in either version of VM NA

HCFC-123

Lower emissions in VM4.4 through 

2020, then higher emissions through 

2050

Used as a flooding agent (through 2014) and chillers (no 

phaseout)

HCFC-124 Lower emissions in VM4.4 Relatively small uses in Ref, sterilization, and FireExt

HFC-125

Introduced sooner in VM4.4; similar 

emissions through 2030 then fewer 

emissions than VM 1999 through 2050

Used as an alternative in flooding agents, chillers, IPR, 

and other refrigeration equipment, but not the most 

common ODS replacement for those end uses

HFC-134a Higher emissions in VM4.4, not phased 

out in latest VM

Reflection of the high uses of HFC-134a (most 

commonly used HFC; used in Ref, AC, aerosols, and 

foam applications)

HCFC-141b

Historically similar emissions; VM4.4 

emissions higher between 2010 and 

2040, then lower than VM 1999 from 

2041–2050

HCFC-141b used in foams with long lifetimes (between 

14 and 56 years) 

33
Table F.1: Explanation of Differences between VM1999 and VM2012 cont.

Species Differences Explanation for Differences

HCFC-142b

Introduced sooner in VM4.4 and with 

higher emissions continuing through 

2050

Used in as a Ref blend and in foam; Emissions due to 

leakage and disposal

HFC-143 Not included in VM 1999 NA

HFC-152 Higher emissions in VM4.4 HFC use has grown significantly

CFC-114 Relatively close

CFC-114 used in chillers, foams, and aerosols. Not 

completely phased out of MDI aerosol use until 2014

CFC-115 Higher emissions in VM4.4 Refrigerant blend in large equipment (transport, large 

retail food, cold storage) with 20+ year lifetimes 

34