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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

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em s

usta

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ility

Wat

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uppl

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egul

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Supp

ly

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tura

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irit

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nd E

duca

tio

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supp

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Aes

thet

ics

Foo

d Pr

ovi

sio

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Wat

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urif

icat

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Was

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Trea

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Pro

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Hum

an H

ealt

h

Clim

ate

Reg

ulat

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car

bon

sequ

estr

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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

psinha@rti.org

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