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Monetizing the Health Impacts of Wood Smoke in the Pacific Northwest
April 10, 2014
Abt Associates | pg 2
Project Overview
Task A – Collect Data
Task B – Estimate Baseline Wood Smoke Emissions
Task C – Estimate Scenario Wood Smoke Emissions
Task D – Monetize Health Impacts
Abt Associates | pg 3
Baseline Wood Smoke Emissions
Data sources used to estimate baseline wood smoke emissions include the Residential Building Stock Assessment (RBSA) and the U.S. EPA Residential Wood Combustion (RWC) tool– RWC Tool: all counties in Oregon & Washington; Ada,
Canyon, & Elmore, Idaho; Lincoln & Silver Bow, Montana – RBSA: all other counties in Idaho and Montana
Abt Associates | pg 4
Baseline Wood Smoke Emissions
Baseline methodology relies on two key factors: Appliance fraction: the percentage of homes in the
county with each type of wood burning appliance Burn rate: the amount of wood (cords or tons) burned
in each appliance in each year Unique appliance fractions and burn rates are
calculated for each combination of appliance type, burn type, and house type
Abt Associates | pg 5
Baseline Wood Smoke Emissions
Appliance Burn Type House Type
Fireplace Primary Single-family
Wood stove (non-certified) Secondary Multi-family
Wood stove (certified non-catalytic) Manufactured homes
Wood stove (certified catalytic)
Fireplace insert (non-certified)
Fireplace insert (certified non-catalytic)
Fireplace insert (certified catalytic)
Pellet stove
Wood-fired furnace
Wood-fired boiler
Outdoor burning (e.g. firepits)
Abt Associates | pg 6
Baseline Wood Smoke Emissions
Baseline emissions calculation: Baseline emissions (tons) =
Number of homes × Appliance fraction ×
Burn rate (cords/year) ×
Density of firewood (tons/cord) ×
Emission factor (tons of pollution/tons of wood)
Number of appliances
Number of cords
Convert cords to tons
Calculate tons of pollution
Abt Associates | pg 7
Scenario Wood Smoke Emissions
Scenarios reduced emissions for all appliances used primarily for heating:– All types of wood stoves, pellet stoves, wood-fired furnaces, and wood-fired
boilers– Did not include fireplaces or outdoor burning (e.g. firepits); these emissions
were left unchanged Analysis included 4 scenarios:
– 25% reduction– 50% reduction– 75% reduction– 100% reduction
Abt Associates | pg 8
Baseline and Scenario Emissions
Abt Associates | pg 9
Monetized Health Impacts: Method
U.S. EPA’s Co-Benefits Risk Assessment (COBRA) modelQuantifies Changes in Air Quality- Uses a simple air quality model, the Source Receptor (S-R) Matrix, to estimate effects of
changes on ambient particulate matter.
Calculates Change in Health Outcomes- Uses “canned” concentration response functions to
link the changes in particulate matter to epidemiological studies
Outputs = Tables and maps of illnesses and deaths avoided and the
related economic value.
Calculates Monetary Value- Uses “canned” values based on willingness-to-
pay, cost of illnesses , value of a statistical life and direct medical costs.
Modified the baseline for wood smoke emissions to match estimates for the PNW
Adjusted the outputs for population and income growth to match council values
Abt Associates | pg 10
Monetized Health Impacts: Adjustments
Population adjustments– Using county-level ratios of the Council’s 2017
population projections to the 2017 population in COBRA
Income growth adjustments– For economic values, based on willingness-to-pay
estimates
– Using the ratio of Council data-based income growth adjustment factors to the factors supplied by EPA
Abt Associates | pg 11
Monetized Health Impacts: Results
Avoided cases of adverse health effects, and their associated economic values– “Low” and “high” estimates based on different (EPA-
approved) assumptions about sensitivity of adult mortality and non-fatal heart attacks to changes in ambient PM2.5 levels
– COBRA discounts the estimated stream of economic benefits to the year 2017, since some health benefits from 2017 emissions reductions will occur in later years
Abt Associates | pg 12
Monetized Health Impacts: Results
Health Incidence Results for Study AreaHealth Incident Avoided Number of Cases Avoided 25% Reduction 50% Reduction 75% Reduction 100% Reduction
Adult Mortality 55-126 111-251 166-376 222-501Infant Mortality >0 >0 >0 >0Non-fatal Heart Attacks 6-54 12-108 17-161 23-214Hospital Admissions 25 50 75 100Acute Bronchitis 91 182 273 364Respiratory Symptoms 2,829 5,654 8,476 11,295Asthma ER Visits 24 48 72 95MRAD 48,683 97,316 145,898 194,430Work Loss Days 8,220 16,435 24,645 32,849Asthma Exacerbations 1,745 3,489 5,232 6,975
Abt Associates | pg 13
Monetized Health Impacts: Results
Monetized Value Results for Study AreaHealth Incident Avoided Economic Value (Millions 2010$, 7% discount rate) 25% Reduction 50% Reduction 75% Reduction 100% ReductionTotal Health Effects $425.8 - $960.9 $851.3 - $1,920.0 $1,276.5 - $2,877.5 $1,701.3 - $3,833.3
Adult Mortality $418.1 - $947.4 $835.9 - $1,893.2 $1,253.3 - $2,837.3 $1,670.4 - $3,779.7
Infant Mortality $1.1 $2.1 $3.2 $4.3
Non-fatal Heart Attacks $0.7 - $6.4 $1.4 - $12.8 $2.1 - $19.1 $2.8 - $25.4
Hospital Admissions $0.8 $1.7 $2.5 $3.4
Acute Bronchitis >$0.0 $0.1 $0.1 $0.2
Respiratory Symptoms $0.1 $0.2 $0.2 $0.3
Asthma ER Visits >$0.0 >$0.0 >$0.0 >$0.0
MRAD $3.3 $6.6 $9.9 $13.2
Work Loss Days $1.6 $3.2 $4.8 $6.4
Asthma Exacerbations $0.1 $0.2 $0.3 $0.4
Abt Associates | pg 14
Monetized Health Impacts: Results
0% 25% 50% 75% 100%$0
$500
$1,000
$1,500
$2,000
$2,500
$3,000
$3,500
$4,000
$4,500
f(x) = 1701.31942174323 x + 0.334594038900832
f(x) = 3833.25397375823 x + 1.70010454201338
High EstimateLinear (High Estimate)
Wood Smoke Emissions Reduction
Tota
l Hea
lth B
enef
its (M
illio
ns $
)
0% 25% 50% 75% 100%0
100
200
300
400
500
600
f(x) = 221.532584143599 x + 0.0436241824237271
f(x) = 501.266276511229 x + 0.222011298122027
High Estimate
Wood Smoke Emissions Reduction#
of A
dult
Dea
ths
Avo
ided
Total Health Benefits in 2017 Avoided Adult Mortality in 2017
Abt Associates | pg 15
Monetized Health Impacts: Results
mg/m3 PM2.5
Improvements in Ambient Air Quality
Abt Associates | pg 16
Monetized Health Impacts: Results
Total Health Benefits
Abt Associates | pg 17
Monetized Health Impacts: Results
Changes in PM2.5 Emissions
Value of Total Health Effects Avoided
Abt Associates | pg 18
Monetized Health Impacts: Results
Comparing Health Benefits to Increased Electricity Usage Estimated the amount of electricity needed to displace wood heat with ductless
heat pumps (DHPs):– Usable heat to displace (kWh) = Wood burned (tons) × Btu/ton of wood × Appliance Efficiency × kWh/Btu
– Grid DHP Electricity Consumption (kWh) = Usable heat from woodstoves /
DHP COP × Grid Loss Factor
– Benefits per kWh = Total Health Benefits / DHP Electricity Consumption
Total benefits for PNW study area: $0.72 - $1.61 per kWh of electricity used by a DHP to displace wood heat
Abt Associates | pg 19
Applications and Limitations Applications
– Significant annual health benefits across PNW study area identified by screening-level assessment provide justification for performing a more in-depth analysis of benefits associated with wood smoke emissions reductions
– A value range ($/kWh) that can be used in a benefit-cost analysis of policies or programs that target the entire PNW study area to replace wood burning appliances with DHPs
– A customized version of COBRA to allow future scenario analyses
Limitations– Results can only be interpreted at the study-area level; more analysis is needed to
determine more spatially targeted results (e.g. county level)– Results only examine benefits, but do not include costs of reducing wood smoke or
for increases in emissions from EGUs (e.g. to power DHPs)– Analysis does not fully account for all uncertainties, including population and
income projections and air dispersion algorithms
Abt Associates | pg 20
Suggested Future Analyses
Spatially targeted results– Current results can only be interpreted across the entire study area– Spatially targeted results would look at smaller (e.g. county-level) areas to
determine benefits of emission reductions on a smaller spatial scale Compare benefits to costs of reducing wood smoke emissions
– Incentives to reduce burning and/or to install DHPs or other heating devices– Education campaigns to inform residents about wood smoke emissions– Regulations to control wood smoke emissions
Examine emissions from redispatching electricity– The current analysis does not adjust the benefits to account for any emissions
that might arise due to an increase in use of DHPs to displace wood heat
Abt Associates | pg 21
Acknowledgements
Special thanks to: Mohit Chhabra, Ptarmigan Research
Charlie Grist, Northwest Power and Conservation Council
RTF Wood Smoke Subcommittee
Ben Larson, David Baylon, Ecotope Inc.; Christian Douglass, Ptarmigan Research
Questions?Abt Contact Information
Jonathan G. Dorn, Ph.D., M.P.PJonathan_Dorn@abtassoc.com
919-294-7763