1

External Costs of Air PollutionAri Rabl, ARMINES/Ecole des Mines de Paris ari.rabl@gmail.com and www.arirabl.org

October 2014

External Costs = cost that are not taken into account by the market

e.g. damage costs of pollution, if polluter does not pay,

= costs imposed on others

perspective of society perspective of individual

Need government regulations to internalize external costs(make polluter take into account the external cost, i.e. act as if polluter and victims were the same)

Part of the damage costs are already internalized by current regulations, and some economists define external cost as only that part of the damage cost that still remains to be internalized (but that is difficult to determine and very uncertain). In practice most people now refer to the entire damage cost of pollution as “external cost”.

2

Sources of Pollution

Most air pollution,(and a large part of all pollution)

is directly or indirectly linked to energy (electricity, heat, transport)

Combustion of fossil fuels:

CO2 ( global warming)NOx ( acid rain, tropospheric O3, health impacts)

SOx ( acid rain, health impacts) black smoke, particles ( health impacts)

other: nuclear waste

CFCs (insulation, refrigeration) ( stratospheric O3 hole)land use (power plants, mines, wastes, ...)

accidents (mines, Chernobyl, ...)Noiseetc …

3

How much is clean air worth?

Difficult choices(high costs):e.g.

pay extra for clean energy? photovoltaics?"zero emission" vehicles? fuel cell car?improved flue gas treatment? e.g. catalytic reduction of NOx close a factory with high pollution? cancers or jobs?

Excessive spending for environmental protection takes money away from other worthy causes, such as education

and public health

Cost-benefit analysis (CBA)can help optimize allocation of scarce resources,

i.e. compare costs and benefits of pollution abatement

pollution abatement = measures to reduce pollution

4

Cost-Effectiveness Analysis (CEA)

= Ranking of abatement measures in terms of their result/cost ratio.Example: CO2 abatement in EU by 2020 (reference: IIASA, GAINS model)

Each segment of the curve represents marginal cost (€/tCO2) and contribution to abatement (GtCO2/yr) of a particular abatement measure, e.g. replacement of incandescent lighting by fluorescent.

CEA does not tell us

how far we should abate;

for that we need to

know also the benefits (cost-benefit

analysis)

5

Criteria for Determining Optimal Level of Pollution

1) Zero pollution: Unrealistic, our economy could not function

2) Stay below threshold of harmful impacts: OK if there is such a threshold (often the case for ecosystem impacts)

but for many pollutants/impacts there is no such threshold,e.g. greenhouse gases, health impacts of NOx, PM, SO2, O3, carcinogens, …

3) Precautionary principle: no useful guidance

4) Minimize the total social cost Ctot(E) = Cdamage(E) + Cabatement(E)as function of pollution emission E

Marginal damage cost = - marginal abatement cost

6

The Precautionary Principle

only a general guideline (“Think before you act!”), no advice for specific problems

Must be used with a great deal of precaution, to avoid unexpected consequences

e.g. Overestimating risks of nuclear implies increased global warming and conventional pollution

Overestimation of mortality costs of pollution implies increased mortality through indirect impacts (“poverty kills”)

Whose risks, whose precaution?

We need expectation value of damage costs, except for cases where valuation is very non-linear function of damage (e.g.

very large accident, or irreversible damage)

7

Optimal level of pollution, cont’d

General case (almost always): Marginal abatement cost

decreases with E

Typical case for classical air pollutants: Marginal damage cost

= constant

for CO2: Marginal damage cost increases with E

At optimum

Example: costs of CO2

8

Information Needs of Policy Makers

Environmental policies need to target specific pollution sources

General policies, e.g. ambient air quality standards, are not sufficient

Policy makers must tell each polluter how much to reduce the emission of each pollutant (e.g, NOx from cars = precursor of

O3 and PM10) They need to know impact (cost) of emitted pollutant

For some decisions the also need LCA results, e.g. • choice between nuclear and coal,• electric or fuel cell vehicles (“pollution elsewhere

vehicles”),• hydrogen economy

9

Towards an answer:

the ExternE Project Series of the EC ExternE = “External Costs of Energy”

Series of research projects

funded by European Commission DG Research, since 1991 (until 1995 with ORNL/RFF)

>200 scientists in all countries of EU(A. Rabl is one of the key participants)

Major publications 1995, 1998, 2000, 2004,

and 2008 (definitive results)

www.externe.info

Methodology

1) Life Cycle Assessment of process or product chain (LCA)

2) Site specific Impact Pathway Analysis (IPA)

10

Impact Pathway Analysis

to calculate damage of a pollutant emitted

by a source

Impacts are summed over entire region that is affected (Europe) and all damage types that can be quantified:• health• loss of agricultural

production• damage to buildings

and materials

Result: €/kg of pollutant

Multiply by kg/kWh to get €/kWh

11

Pathways for Dioxins and Toxic MetalsFor many persistent pollutants (dioxins, As, Cd, Cr, Hg, Ni, Pb, etc)

ingestion dose is about two orders of magnitude higher than inhalation

12

Life cycle analysis (LCA)Relation between impact pathway analysis and current practice of most LCA,

illustrated for the example of electricity production.

LCA should include site-specific IPA with realistic exposure-response functionsand monetary valuation - but that’s usually not done in current practice.

13

Comparison LCIA ExternE

Impact 2002+ ExternE

Monetary valuation no yes

Pollutants considered All for which emissions data

available

CO2,CH4,N2O,PM,SO2,NOx,VOC,

As, Cd, Cr, Hg, Ni, Pb,dioxins, benzene, radionuclides

Impact categories

Human toxicity X X

Global warming X X

Ionizing radiation X X

Photochemical oxidation X X

Terrestrial acid/eutroph X X

Land use X X

Ozone layer depletion X

Aquatic ecotoxicity X

Terrestrial ecotoxicity X

Aquatic acidification X

Aquatic eutrophication X

Non-renewable energy X

Mineral extraction X

Agricultural losses X

Buildings and materials X

Accidents X

Energy supply security X

Amenity impacts X

Impact 2002+ is the most complete LCIA

(life cycle impact assessment)

Impact 2002+, like most LCA:

no monetary valuation,and tries to include

everything (even if the ERFs are dubious)

whereas ExternE focuses on items with the largest damage cost, trying to be as realistic as possible

14

Comparison LCIA ExternE

Impact 2002+ ExternE

Monetary valuation no yes

Pollutants considered All for which emissions data

available

CO2,CH4,N2O,PM,SO2,NOx,VOC,

As, Cd, Cr, Hg, Ni, Pb,dioxins, benzene, radionuclides

Impact categories

Human toxicity X X

Global warming X X

Ionizing radiation X X

Photochemical oxidation X X

Terrestrial acid/eutroph X X

Land use X X

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Comparison LCIA ExternE

Impact 2002+ ExternE

Ozone layer depletion X

Aquatic ecotoxicity X

Terrestrial ecotoxicity X

Aquatic acidification X

Aquatic eutrophication X

Non-renewable energy X

Mineral extraction X

Agricultural losses X

Buildings and materials X

Accidents X

Energy supply security X

Reduction of visibility

16

Comparison of tools for evaluating environmental policy options

Very limited and simplified list

Tool Description Monet.valuation

Life Cycle Assessment (LCA)

1) LCA Inventory (material flows, pollutants): crucial for evaluating products or processes

2) LCA Impact Assessment: dubious methodology because no realistic dispersion models and

exposure-response functions Use IPA instead!

no

Cost-Effectiveness Analysis (CEA)

Costs and results (quantity of pollution that is avoided) of options are quantified and ranked according to

ratio result/cost

no

Impact Pathway Analysis (IPA)

Analysis of the chain emission dispersion dose-response function cost

yes

Cost-Benefit Analysis (CBA)

Evaluate and compare costs and benefits of options yes

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Monetary valuation

e.g.

VSL = “Value of Statistical Life”

(a better name VPF = value of prevented fatality)

= WTP to avoid risk of an anonymous premature deathtypical values used in EU and USA 2-5 M€

Value of a Life Year (VOLY) due to air pollution = 40,000 €

Methods for valuation of non-market goods:• Contingent valuation (survey of individuals)• analysis of consumer choices (e.g. lower rent for noisy

apartments, travel cost, higher wage for higher risk, etc)

For non-market goods:

based on Willingness-to-pay (WTP) to avoid a loss

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Land use, waste storage

Land use:Serious impact on ecosystems and biodiversity (biodiversity decreases if size of an ecosystem is reduced, e.g. if it is cut by a road)

Very site-specific.

Storage of waste (nuclear and conventional):Difficulty: damage depends on future management of storage,with new technologies leakage during the operation of the facility is negligible, but what will happen in the future?

Þneed scenariosExternE: assessment of waste storage for nuclear, but so far

not for fossil fuel chains

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Nuclear power

ExternE 1995 and 1998: Very low damage costs (lowest of all except wind, solar and for some sites hydro)

but …

Risks of nuclear proliferation and terrorism:Temptation to increase profit and economies of scale by selling the technology to

countries that lack sufficient safeguards (the link nuclear power -> military is undeniable)

Risks of major nuclear accident:ExternE 1995: Extremely small with new technologies, but public

perception?

Long term storage of waste:No problem as long as storage site is supervised. But is our society

stable enough in the long term?

Risks imposed on future generations: nuclear waste vs. CO2

20

Health impacts of pollutionPrimary Pollutant Secondary

Pollutant Impacts

particles(BS, PM10, PM2.5)

Mortality Cardio-vascular and respiratory morbidity:

reduction of lung capacity, lung cancer, asthma, bronchitis

(hospitalization, sick leave, doctor visits, …)

SO2

Direct effects of SO2?Mortality

Cardio-vascular and respiratory morbidity

SO2sulfates like particles?

NO2 direct effects of NO2? Mortality and morbidity?

NOxnitrates like particles?

Are the observed impacts due to particles or due to NO2 or SO2?

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Primary Pollutant Secondary Pollutant

Impacts

NOx+VOC ozone mortality respiratory morbidity

VOC (volatile organic compounds)

little or no direct effects at typical ambient concentrations (except PAC)

Benzene, PAC (polycyclic aromatic compounds)

cancers

CO mortalitycardio-vascular morbidity

dioxins Cancers, other morbidity

As, Cd, Cr, Ni Cancers, other morbidity

Hg, Pb morbidity (neurotoxic, other)

Health impacts of pollution, cont’d

22

Health effects of air pollution

Healthy individuals have sufficient reserve capacity not to notice effects of pollution, but the effects become observable at times of low reserve (during extreme physical

stress, severe illness, or last period of life)

Pollution reduces reserve capacity

Mortality impact is not the loss of a few months of misery at the

end but the shrinking of the entire quality of life curve (“accelerated

aging”)

In large population there are always some individuals with very

low reserve capacity impacts observable

23

Approaches to measure health impacts

1) Epidemiology:

comparing populations with different exposures.

2) Laboratory experiments with humans:

exposure in test chambers with controlled concentration of air pollutants (but this approach is very limited because of ethical constraints).

3) Toxicology:

a) Expose animals (usually rats or mice) to a pollutant; sample sizes are usually very small compared to epidemiological studies, and the animals are selected to be as homogenous as possible (unlike real populations). Extrapolation to humans???

b) Expose tissue cultures to pollutants. Extrapolation to real organism???

24

Approaches to measure health impacts, cont’d

Epidemiology: can measure impacts on real human populations, by observing correlations

(“associations”) between exposure and impact. But in most cases the uncertainties are very large. Is the

impact due to the pollutant or due to other variables that have not been taken into account (the problem of

“confounders”, especially smoking)?

Toxicology: can identify mechanisms of action of the pollutants. For many substance tests with animals

are the only way to identify carcinogenic effects. Toxicology can also suggest new questions to be

investigated by epidemiology.

The two approaches are complementary.

25

Dose-response functions (DRFs)

(for air pollutants also known as exposure-response functions or concentration response functions)

Crucial for calculating impacts of a pollutant.

Note:

a) most epidemiological studies do not report explicit DRFs but only a relative risk (= increase in occurrence of a health impact due to increase of exposure). To obtain DRF one also needs data on background rates of occurrence.

b) Watch out for consistency of DRF with the specification of exposure (calculated by dispersion models) and with monetary valuation. E.g. is exposure specified as hourly peak or as 24 hr average?

26

Form of exposure-response functions (ERF) at low doses (also known as dose-response function)

Possible functional forms at low doses

Linearity without threshold

is the most plausible assumption for NO2, PM, O3, SO2, and

carcinogens (including radiation)

Difference between ERFs for individuals and for populations

Toxicology: small samples of identical individuals threshold

Epidemiology: real populations with large variations of sensitivity often no threshold

27

Importance of Mortality

In terms of costs, the most important emitted pollutants

(apart from greenhouse gases) are

PM,

SO2 (precursor of sulfate aerosols),

NOx and VOC (precursors of O3).

About 65% of their total damage cost is due to mortality!

About 15% due to chronic bronchitis,

About 15% due to other health impacts,

Only a few % due to agricultural losses, and damage to buildings

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Loss of Life Expectancy due to Air Pollution

In EU and USA typical concentrations of PM2.5 around 20 - 30 g/m3 LE loss 8 months

Reasonable policy goal during coming decades:reduction by about 50%

Life expectancy (LE) gain about 4 months Other countries, e.g. China: concentrations ~2 to 3higher

total LE loss ~2 to 4 years

To put this in perspective with other public health risks:Smokers lose about 5 to 8 years on average

Rule of thumb: each cigarette reduces LE by about the duration of the smoke

Air pollution (in EU and USA) equivalent to about 4 cigarettes/day

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How to measure the impacts and costs of air pollution mortality

Key issue for environmental policy because most of total damage cost of pollution is due to mortality

VPF used for accidents, Loss of LE for public health

??? ???

Loss of life expectancy VOLY

VOLY = Value of a Life Year

or

Number of deaths VPFVPF = Value of Prevented Fatality (=VSL = “Value of Statistical Life”)

= “willingness-to-pay to avoid an anonymous premature death”

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Number of deaths VPF:mediagenic but wrong

1) VPF based on accidents (large LE loss/death) air pollution

2) True number of air pollution deaths is not knowable (at current state of science):• “air pollution death” = death advanced by air pollution

not a primary cause of death• Cohort studies cannot distinguish if observed mortality due to everybody

losing a little or a few a lot

if everybody loses some LE, all deaths are “air pollution deaths”

• The calculation of number of deaths from cohort studies is wrong because it does not take into account change in age structure during future years

• Number of deaths from conventional time series studies includes only acute effects (very small LE loss compared to total)

3) LE loss due to air pollution can be determined

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Primary Pollutant Secondary Pollutant

Impacts

NOx+VOC ozone Damage to plants and ecosystems,damage to some materials

NOx Damage to ecosystems (Acidification, eutrophication)

SO2 acid rain Damage to plants and ecosystems damage to some materials

particles Soiling of buildings

CO2, CH4, N2O,

CFCs

Global warming

CFCs Destruction of stratospheric O3

Other Effects of Air Pollutants

32

Global warming, causes

33

Global temperature and sea level, past

From: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-ts.pdf

34

Scenarios and temperature change

From: http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr.pdfSRES = Special Report on Emission Scenarios

35

Predicted changes

in precipitation

For the A1B scenario and comparing the period 2080 to 2099

with the control period1980 to 1999

From: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter11.pdf

36

Physical impacts of global warming

Ref: http://www.ipcc.ch/pub/wg2TARtechsum.pdf (Table.TS-1)Pre-industrial concentration = 280 ppm

• Changes of heating and cooling• Changes of agricultural production• Increased incidence of tropical diseases (malaria, dengue fever, …)• Migrations of displaced populations• Extreme weather events (costs = ??) • Ecosystem impacts: species extinction, … (costs = ????)• Social and political problems, especially in poor countries (costs = ????)• Changes in ocean circulation (could be abrupt, ~years)

Some will gain but most will lose

37

Monetary valuation of global warming

Various estimates for 2xCO2

loss on the order of 1 to 3 % of gross world product

Cost per ton of CO2

depends on discount rate and other controversial assumptions

especially “value of life” in developing countries (where most of the damage will occur)

mainstream estimates are around of 20 €/t of CO2

(but is it agreement by imitation?)

Valuations by ExternE

ExternE 1998:Calculations by ExternE team: 3.8-139 €/tCO2

18-46 €/tCO2 (“restricted range”, geometric mean 29 €/tCO2 )

ExternE 2000: 2.4 €/tCO2

ExternE 2008: 21 €/tCO2

38

Global warming cost, recent estimates by UK

Studies in 2004 and 2005 (literature review and detailed modeling)

Report by Stern et al in 2006Damage cost around 85 $/tCO2 (65 €/tCO2)

39

Current emissions and implications of a CO2 tax

Germany 10 tCO2/yr France 6 tCO2/yr

If tax = 20 €/tCO2: for 6 tCO2/yr

per per person cost = 120 €/yr

per person (France)Implication for electricity

(note current average price

~11 cents/kWh):

gas (combined cycle)

0.4 kg/kWh0.8 cents/kWh

coal (steam turbine)

0.9 kg/kWh1.8 cents/kWh Stabilization at 550 ppm

40

What do to about global warming?

Reduce emissions• Shift to renewables or nuclear• Increase efficiency of fossil energy use• carbon sequestration (storing CO2 in depleted reservoirs

of natural gas or oil, in aquifers, deep ocean, …)• Life style changes, e.g. eat less red meat, more vegetarian

food

Adaptive measures to reduce impacts, e.g.• develop drought resistant crops • change crops• build dikes

41

Impacts and Technologies evaluated by ExternE

Impacts

1) Global warming (CO2, CH4, N2O)

2) NOx, SO2, PM etc (primary & secondary pollutants)

• Health (morbidity: ~ 30%, mortality: ~65% of total cost of these pollutants)The rest is only a few %:

• Buildings & materials• Agricultural crops• acidification & eutrophication

3) Other burdens• Amenity (noise, visual impact, recreation)• supply security

Technologies• Energy: coal, lignite, oil, gas, biomass, PV, wind, hydro, nuclear• Waste: incineration, landfill• Transport: cars, trucks, bus, rail, ship, (planes)

42

Key Assumptions of ExternELocal + regional dispersion models

Linear dose-response functions for health (no threshold):Mostly PM2.5, PM10, O3

A few for SO2 and NO2

Sulfates are assumed like PM10, Nitrates like 0.5 PM10

also As, Cd, Cr, Hg, Ni and Pb

Mortality in terms of LLE (loss of life expectancy) rather than number of deaths

Monetary valuation based on Willingness-to-pay (WTP) to avoid a loss:

Value of a Life Year (VOLY) due to air pollution = 40,000 €

Cancers 2M€/cancer, based on VSL = 1 M€

(VSL = “Value of Statistical Life” = WTP to avoid risk of an anonymous premature death; typical values used in EU and USA 1-5 M€)

43

Damage Cost per kg of Pollutant,and uncertainty

(error bars),according to

ExternE [2008]

Note: somewhat different numbers in different publications (due to progress in methodology)

h = stack heightPMco = 2.5 – 10 mm

21 €/tCO2

44

Results for Power PlantsTypical numbers for EU27 [ExternE 2008]. Market price ~11cents/kWh (France 2011)

45

Results for Waste TreatmentNet impact very dependent on energy recovery. Some examples:

Other = toxic metals (mostly Hg and Pb) and dioxins (very small with current regulations)

Energy recovery replaces

H = heatE = electricityg= gaso = oilc = coal

Compare with private costs:Incineration

~ 100€/twaste

Landfill~ 50€/twaste

46

Atmospheric models for damage costs There are many different models for atmospheric dispersion and chemistry, with

different objectives: e.g. microscale models (street canyons), local models (up to tens of km), regional models (hundreds to thousands of km),short term models for episodes,long term models for long term (annual) averages.

For damage costs of air pollution, note that the dose-response functions for health (dominant impact) are linear only the long term average

concentration matters

For agricultural crops and buildings they are nonlinear, but can be characterized in terms of seasonal or annual averages only the long term

average concentration is needed

Dispersion of most air pollutants is significant up to hundreds or thousands of km

need local + regional models for long term average concentrations (they tend to be more accurate than models for episodes)

47

Dispersion of Air Pollutants

Depends on meteorological

conditions:wind speed and

atmospheric stability class (adiabatic lapse rate, see diagrams at

left)

48

Gaussian plume model for atmospheric dispersion(in local range < ~50 km)

49

Gaussian plume modelconcentration c at point (x,y,z)

Underlying hypothesis: fluid with random fluctuations around a dominant direction of motion (x-direction)

c=concentration, kg/m3

Q=emission rate, kg/sv= wind speed, m/s, in x-directiony=horizontal plume widthz=vertical plume widthhe=effective emission height

Source at x=0,y=0

Plume width parameters y and z increase with x

50

Gaussian plume width parameters There are several models for estimating y and z as a function of

downwind distance x, for example the Brookhaven model

where

To use model one needs data for wind speed and direction, and for atmospheric stability (Pasquill class); the latter depends on solar radiation and on wind speed.

51

Gaussian plume with reflection

terms

When plume hits ground or top of

mixing layer, it is reflected

52

Gaussian plume with reflection terms, cont’d

53

Effect of stack parameters

Plume rise: fairly complex, depends on velocity and temperature of flue gas, as well as on ambient atmospheric conditions

54

Removal of pollutants from atmosphere

Mechanisms for removal of pollutants from atmosphere:1) Dry deposition

(uptake at the earth's surface by soil, water or vegetation)2) Wet deposition

(absorption into droplets followed by droplet removal by precipitation)

3) Transformation(e.g. decay of radionuclides, or chemical transformation SO2 NH4)2SO4).

They can be characterized in terms of deposition velocities,(also known as depletion or removal velocities)vdep = rate at which pollutant is deposited on ground, m/s (obvious intuitive interpretation for deposition)

vdep depends on pollutantdetermines range of analysis: the smaller vdep the farther the pollutant travels)

Typical values 0.2 to 2 cm/s for PM, SO2 and NOx

Gaussian plume model can be adapted to include removal of pollutants

55

Regional Dispersion, a simple model,1

Far from source gaussian plume with reflections implies vertically uniform concentrations

Therefore consider line source for regional dispersion (point source and line source produce same concentration at large r)

Assume wind speed is always = v, uniform in all directions f

the pollutant spreads over an area that is proportional to r

56

Regional Dispersion, a simple model,2

Consider mass balance as puffs move from r to r+r mass flow v c(r) H r across shaded surface at r= mass flow v c(r+r) H (r+r) across shaded surface at r+r+ mass vdep c(r +r/2) r (r+r/2) deposited on ground between r and r+r Taylor expand c(r+r) = c(r) + c’(r) r and neglect higher order terms Differential equation c’(r) = - ( + 1/r) c(r) with = vdep/(v H)

Solution c(r) = constant × exp(- r)/r with constant to be determined

57

Regional Dispersion, a simple model,3

Determination of constant by considering integral of flux c(r) v over cylinder of height H and radius r in limit of r 0

This integral must equal to emission rate Q [in kg/s].

or

Final result

This model can readily be generalized(i) To case where wind speeds in each direction are variable with a distribution f(v(), )(ii) To case where trajectories of puffs meander instead of being straight lines: then exp(- r) is replaced by exp(- t(r)) where t(r) = transit time to r.

with

58

Impact vs cutoff rmax

Total impact I = integral of sER c(r) with = receptor density and sER = slope of exposure-response function

Simple case: and sER independent of r and

with

with

If cutoff rmax for integralRange 1/ = v H/vdep = 800 kmfor mixing layer height H = 800 mwind speed v = 10 m/sdepletion velocity vdep = 0.01 m/s

59

Chemical Reactions

Primary pollutants (emitted) secondary pollutants aerosol formation from NO, SO2 and NH3 emissions.

Note: NH3 background,mostly from agriculture

60

Ozone formation

Very simplified:

light, NOx and VOC O3

(VOC = volatile organic compounds)

Really many complex nonlinear processes. A few of the most important reactions

NO2 + h O + NO and O + O2 + M O3 + M

where M is a molecule such as N2 or O2 (participation is necessary because of the law of conservation of energy).

VOCs prevent the ozone formed from being immediately consumed by NO to produce NO2

NO + O3 O2 + NO2

VOCs enable the transformation of NO into NO2 without consuming ozone.

61

Nonlinearity of ozone formation

Nonlinearity depends on VOC concentration optimal strategy for reducing O3 production depends on climate and on existing levels of VOC and NOx

Approximately linear with VOC, but nonlinear with NOx

62

UWM: a simple model for damage costs

Product of a few factors (dose-response function, receptor density, unit cost, depletion velocity of pollutant, …),

Exact for uniform distribution of sources or of receptors

UWM (“Uniform World Model”) for inhalation • verified by comparison with about 100 site-specific calculations by

EcoSense software (EU, Eastern Europe, China, Brazil, Thailand, …);

• recommended for typical values for emissions from tall stacks, more than about 50 m (for specific sites the agreement is usually within a factor of two to three; for ground level emissions damage much larger; apply correction factors).

UWM for ingestion is even closer to exact calculation, because food is transported over large distances average over all the areas where the food is produced effective distributions even more uniform.

Most policy applications need typical values (people tend to use site specific results as if they were typical precisely wrong rather than

approximately right)

63

UWM: derivation

Total impact I = integral of sER c(x) over all receptor sites x = (x,y)

withc(x) = c(x,Q) = concentration at surface due to emission Q Q(x) = density of receptors (e.g. population)

sER = slope of exposure-response function Total depletion flux (due to deposition and/or transformation)F(x) = Fdry(x) + Fwet(x) + Ftrans(x)Define depletion velocity vdep(x) = F(x)/c(x) [units of m/s]Replace c(x) in integral by F(x)/k(x) If world were uniform with uniform density of receptors and uniform depletion velocity vdep

then

By conservation of mass

“Uniform World Model” (UWM) for damage

64

UWM: example for single impact

65

UWM and Site Dependence, example

dependence on site and on height of source for a primary pollutant: damage D from SO2 emissions with linear dose-response function, for five sites in France, in units of Duni for uniform world model (the nearest big city, 25 to 50 km away, is indicated in parentheses). The scale on the right indicates YOLL/yr (mortality) from a plant with emission 1000 ton/yr. Plume rise for typical incinerator conditions is accounted for.

66

Validation of UWM, for primary pollutants

Comparison with detailed model (EcoSense = official model of ExternE)

Factor of two

67

Unit costs Pi (“price”) and ERF slopes sER,i

YOLL = years of life lostLRS = Lower respiratory symptoms

68

UWM for damage cost, €/kgDamage cost rate D [in €/yr] with sum over all impacts i

each with unit cost Pi and ERF slope sER,i

for emission rate Q [in kg/yr]

Therefore Duni/Q = damage cost in €/kg

Careful about units:Convert everything to SI units for all calculations!

Results good for industrial emissions; for transport emissions, must add correction factors,

and the results are very approximate

69

Parameters for UWM

Population density and depletion velocities vdep, in cm/s, selected data for several regions.

From Rabl, Spadaro and Holland [2013]

70

UWM, €/kg, example

For comparison, Externe [2008] finds 24.6 €/kg for unknown stack height

customary units SI units

rho 112person/km2 0.000112person/m2

depletion velocity kp, PM2.5 0.57cm/s 0.0057m/s

Exposure cost PM2.5 = Sum(Pi Serf,i) 38.753(€/yr) per (person·µg/m3) 38753000000 (€/yr)/(person·kg/m3)

emission rate mdot 1kg/yr 3.16881E-08kg/s

damage cost rate Ddot,UWM 24.13€/yr

Since this damage cost rate is for an emission rate of 1 kg/yr, the damage cost per kg is

Damage cost per kg PM2.5 24.13€/kg

Exposure cost 38.753 (€/yr)/(person.mg/m3) = sum of PM2.5 and PM10 terms in table UWM, Pi sER,i = 32.79 + 5.963 (€/yr)/(person.mg/m3)

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Correction factors for UWM for dependence on site and stack height

Example: the cost/kg of PM2.5 emitted by a car in Paris is about 15 times Duni.

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Conclusions, 1

Methodology for calculation of external costs of pollution is well-established (IPA + inventory of LCA)

In principle should be same as LCIA (life cycle impact assessment) but current practice of most LCIA is inconsistent with IPA of ExternE

Results for the most important air pollutants are availablewith applications to almost all important technologies for

• Electricity production• Transport• Waste treatment

External costs were very large; now reduced thanks to new environmental directives, but still significant, especially due to CO2

Can be used for identifying the most cost-effective policies for reducing pollution

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Conclusions, 2

External cost of classical air pollutants mostly due to mortality (~65%) • Valuation of air pollution mortality of adults must be based on LE change,

not number of deaths• VOLY (value of a life year) = 40,000 €• LE (life expectancy) change can be determined with sufficient accuracy

from long term studies ( >10 years)LE loss from permanent exposure to 10 g/m3 of PM2.5 ~ 0.4 year (in US and EU typically 15-25 g/m3 of PM2.5 like 4 cigarettes/day)

Uncertainties are large factor of about 3 for the classical air pollutantsfactor of about 4 for toxic metalsfactor of about 5 for greenhouse gases

Major sources of uncertaintyModeling of environmental fateDose-response functions for healthMonetary valuation of mortality

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Conclusions, 3

Some people think that the uncertainties of ExternE estimates are too large to be useful

However:

1) Better 1/3 x to 3 x than 0 to

2) What matters is not the uncertainty itself, but the social cost of a wrong choice: a) Without cost estimates such costs can be very large, but with ExternE they can be remarkably small in many if not most cases.b) For many yes/no choices the uncertainty is small enough not to affect the answer.

3) Uncertainties can be reduced by a) research and b) guidelines by decision makers on monetary values

(purpose of cost-benefit analysis: make public choices more consistent)

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Glossary

1 ppb O3 = 2.00 g/m3 of O3, 1 ppb NO2 = 1.91 g/m3 of NO2, 1 ppb SO2 = 2.66 g/m3 of SO2, 1 ppm CO = 1.16 mg/m3 of CO (all at 20C)BS = black smoke (fumées noires)c = concentrationCBA = cost-benefit analysisCFC = chlorofluorcarbonCV = contingent valuationERF= dose-response function (also known as exposure-response function or concentration-response function CRF) EC = European CommissionECU = European currency unit (before 1999) = Euro (since 1999)GWP = global warming potential (kg of substance with same radiative forcing as 1 kg of CO2)IPA = impact pathway analysisIPCC = international panel on climate changeLCA = life cycle assessment (ACV = analyse de cycle de vie)LE = life expectancy (espérance de vie)LLE = loss of life expectancyMorbidity impacts = impacts on healthMortality impacts = increased number of deathsNMVOC = non-methane volatile organic compoundsNOx = unspecified mixture of NO and NO2

PMd = particulate matter, with subscript d indicating that only particles with aerodynamic diameter below d, in m, are included (PSd = poussières en suspension)rdis = discount rate (taux d’actualisation) = rate at which one is neutral between a payment P0 today

and a payment Pn = P0 (1+rdis)-n in n years from nowsER = slope of ERF (also called sDR = slope of dose-response function)UWM = uniform world model for simplified approximate calculation of typical impacts and damage costsvdep = deposition velocity of pollutant (also called k = removal or depletion velocity) [m/s]VOC = volatile organic compounds (COV = composantes organiques volatiles)VOLY = value of a life yearVPF = value of prevented fatality (= VSL = “value of statistical life”)YOLL = years of life lost

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References• Rabl, A, Sparado JV, Holland M. 2014. “How Much is Clean Air Worth: Calculating the Benefits of Pollution

Control”. Cambridge University Press, to be published in 2014.

• ExternE 2005. ExternE – Externalities Of Energy: Methodology 2005 Update. Available at http://www.externe.info

• ExternE 2008. With this reference we cite the methodology and results of the NEEDS (2004 – 2008) and CASES (2006 – 2008) phases of ExternE. For the damage costs per kg of pollutant and per kWh of electricity we cite the numbers of the data CD that is included in the book edited by Markandya A, Bigano A and Porchia R in 2010: The Social Cost of Electricity: Scenarios and Policy Implications. Edward Elgar Publishing Ltd, Cheltenham, UK. They can also be downloaded from http://www.feem-project.net/cases/ (although in the latter some numbers have changed since the data CD in the book).

• NRC 2010. “Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use”. National Research Council of the National Academies, Washington, DC. Available from National Academies Press. http://www.nap.edu/catalog.php?record_id=12794

• Rabl 2004. “Pathway Analysis for Population-Total Health Impacts of Toxic Metal Emissions”. Risk Analysis, vol.24(5), 1121-1141.

• Rabl A, J. V. Spadaro & B. van der Zwaan 2005. “Uncertainty of Pollution Damage Cost Estimates: to What Extent does it Matter?”. Environmental Science & Technology, vol.39(2), 399-408 (2005).

• Rabl A, Spadaro JV and Zoughaib A. 2008. “Environmental Impacts and Costs of Municipal Solid Waste: A Comparison of Landfill and Incineration”. Waste Management & Research, vol.26, 147-162 (2008).

• Spadaro JV & A Rabl 2008. “Estimating the Uncertainty of Damage Costs of Pollution: a Simple Transparent Method and Typical Results”. Environmental Impact Assessment Review, vol. 28 (2), 166–183.

Software

EcoSense = software of ExternE for detailed site-specific calculations. Available at http://www.externe.info

RiskPoll = software for simplified calculation of typical impacts and damage costs. Available at http://www.arirabl.org