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Urban Case Study: Methodology to Quantify Avoided Heat-Related Health Effects Due to Tree Cover
Quantifying Ecosystem Services and Co-Benefits of Nutrient and Sediment
Pollutant Reducing BMPs (STAC Workshop)
Annapolis, MD
Paramita Sinha, Jennifer Richkus and Brian Lim
March 29th, 2017
Acknowledgements:
David Nowak, U.S. Forest Service
Background for Case Study
RTI internal grant (Jennifer Richkus) to identify tool to support urban
planners and identify options to enhance/expand tool
– i-Tree: US Forest Service Model
– Framework for assessing ecosystem services provided by urban trees
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– Cooler air temperatures
Building energy use conservation
Avoided health effects : Case study
Climate amenities
– Aesthetics
– Surface water quality
– Structural value
– VOC emissions
– Oxygen production
– Runoff volume reduction
– Carbon storage and sequestration
– UV radiation reduction
– Pollen
– Air pollution removal
Four-Step Approach to Quantify and Value Health Benefits
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Changes in urban tree cover are estimated
Reductions in air
temperature are
estimated
Reduced heat-related
health effects are quantified
Health benefits are monetized
• Method similar to one used to estimate the benefits of air pollutant removal
• UFORE: median externality values for the US for each pollutant (Murray, 1994)
• Nowak et al 2013, 2014:
• BenMAP approach
• Recent application to conduct assessment of Albemarle-Pamlico Watershed’s
Natural Resources
U. S. EPA (2012) Framework : Benefit Category
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Temperature
Reductions*
Reduced Heat-
Related Health
Effects
Public Health Concerns Due to Extreme Temperatures
Extreme heat can result in deaths, emergency room visits,
hospitalizations, and physician visits
Health outcomes/endpoints for extreme heat similar to pollution-related
ones (not exactly same set)
• heat cramps, heat exhaustion (Lippman et al., 2013), and heatstroke (Ostro
et al., 2010);
• exacerbation of chronic conditions, such as cardiovascular disease (Basu &
Ostro 2008), respiratory disease (Basu et al. 2005), cerebrovascular disease
(Basu and Ostro 2008), and diabetes-related conditions (Zanobetti et al.,
2012); and
• prolonged exposure can lead to increased hospital admissions and deaths
(Lin et al. 2009, Fletcher et al., 2012, Basu & Ostro 2008).
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Four-step Approach for Estimating Benefits of Trees
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General approach for
valuing benefits from
trees
Case study-specific
approach
Source/Module
1. Assesses the current
forest structure
Changes in tree cover High resolution tree cover
maps
2. Quantify the service
provided by structure
Reductions in
temperature
Heisler et al. 2015
(module in development)
3. Determine the impact of
service
Reductions in heat-
related health effects
Epidemiological literature
baseline incidence rate
exposed population
4. Estimate the value the
impact
Value reductions in the
risk of death or morbidity
Valuation literature
Step 1. Changes in Tree Cover (i-Tree, 2016)
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Step 2. Reductions in Temperature (Enviroatlas, 2016)
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∆T is the estimated change in extreme heat
– metrics used to characterize “extreme heat” varies widely
– general consensus: metrics suitable for each location should be used (Example:
include humidity when determining ambient temperature in humid areas but less
useful in arid climates)
y0 is the baseline health incidence rate for the health endpoint
Pop is the exposed population
β represents the relationship between the change in temperature and
the health effect
• Estimates of β are derived from the relative risk or odds ratio measures that are
provided by epidemiological studies
Step 3. Reductions in Heat-related Health Effects
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Health Impact Function: Voorhees et al (2010)
∆y = y0 * (eβ∆T -1) *Pop
Estimating the benefits of reduced temperatures in monetary terms
– for each prevented health effect and each population sub-group
∆B = ∆y * V
∆B is the economic value of the each avoided health effect due to
reduced temperatures
∆y is the estimated health effect for each population sub-group
V is an average estimate of the economic value for each prevented
health
Once the dollar values are estimated for each health effect and each
age group, they can be aggregated to estimate the total benefits of
avoided health effects due to reduced temperatures.
Step 4. Economic Value of the Avoided Health Impacts
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Case Study: Implementing for Baltimore and New York
City
– Gathered data on estimated coefficients, incidence data, value
estimates, population (in i-Tree)
– Need to ensure that all inputs are consistent with the specific
sub-population to the extent feasible: ongoing at RTI
– Calculation of changes in extreme heat: ongoing at USFS
Next steps: Expand i-Tree along other dimensions
– Values households attach to avoid hot summers?
– Aesthetics?
– Surface water quality?
Current Status and Next Steps
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STAC Workshop Context: Examples in BMP Matrix
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Sector BMP Group Eco
syst
em s
usta
inab
ility
Wat
er S
uppl
y an
d R
egul
atio
n
Haz
ard
Mit
igat
ion
Rec
reat
ion
Supp
ly
Cul
tura
l, Sp
irit
ual a
nd E
duca
tio
nal
supp
ort
Aes
thet
ics
Foo
d Pr
ovi
sio
ns
Wat
er P
urif
icat
ion&
Was
te
Trea
tmen
t to
Pro
tect
Hum
an H
ealt
h
Clim
ate
Reg
ulat
ion,
car
bon
sequ
estr
atio
n
Hum
an H
ealt
h Su
ppo
rt (o
ther
tha
n
wat
er)
Agriculture Ag Forest Buffer
Agriculture …
Forestry Forest Conservation
Forestry Forest Harvesting Practices
Forestry/Urban Dirt/Gravel Roads
Urban Urban Forest Buffers O O O X
Urban …
Urban Urban Tree Planting O O O X
Urban …
X: Current work
O: Next steps
Questions/ Comments?
More Information:
Paramita Sinha
202.974.7875
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