扒哥吃瓜

This guidance details the process for assessing the air quality impact of a policy or project using damage costs.

Read the assess the impact of air quality and choosing an approach pages to determine which appraisal approach is most appropriate before using this page.

1. Description

The Department for Environment, Food and Rural Affairs (Defra) have developed 鈥榙amage costs鈥� and 鈥榓ctivity costs鈥� to enable proportionate analysis when assessing air quality. Damage costs and activity costs are a set of pre-calculated values, which are derived using the听more detailed Impact Pathways Approach (IPA).

Damage costs are measured per tonne of emissions and activity costs are expressed in pence per kilowatt hour or pence per litre of fuel consumed. They only consider impacts within the UK and don鈥檛 include damage from transboundary effects of UK emissions in other countries.

For further details on the development of these costs go to the .

2. Damage costs

When you know the changes in pollutant emissions and do not require the full IPA users should apply damage costs per tonne of emissions, which can be combined with emission change estimates or forecasts to provide an approximate valuation of the aggregate impacts of a policy.

Use the damage costs per tonne of emissions toolkit to calculate the net present value of the change in air pollution for your scheme. Damage costs are produced for 5 pollutants:

• Nitrogen oxides (NOx)
• Particulate matter (PM2.5)
• Sulphur dioxide (SO2)
• Volatile organic compounds (VOCs)
• Ammonia (NH3)

There are three sets of damage costs per tonne of emissions available depending on what is most appropriate for your policy:

• national damage costs
• sector specific damage costs
• large industrial processes damage costs

Sector specific damage costs and large industrial processes damage costs are only available for emissions of NOx and PM2.5. Therefore, for emissions of SO2, VOCs and NH3 the national damage costs should be used.

When the sector that PM2.5 or NOx emissions are sourced from is not known then the national average damage costs should be used. When PM2.5 or NOx emissions are sourced from a particular sector then the sector specific damage costs should be used. When PM2.5 or NOx emissions are from large industrial processes, you should use the 鈥楶art A sector鈥� damage costs.

Go to annex 1 for all damage costs per tonne of emissions data.

2.1 National damage costs

If your policy covers SO2, VOCs and NH3 emissions or PM2.5 or NOx emissions where the sector is not known then use the national average damage costs. Go to table 3 in annex 1 for the national damage costs data.

2.2 Sector specific damage costs

The impact of emissions on exposure to ambient concentrations varies for different sources and geographically, since it depends on the release characteristics of the emissions and the proximity of these emissions to centres of population. If your policy covers emissions particular to a sector (other than from large industrial processes) then use the sector specific damage costs. Go to tables 4 and 5 in annex 1.

When the specific sector the emissions are sourced from is known but the geographical area type is not, users should apply the relevant average sectoral value. For three sectors (road, rail and domestic), damage costs are provided at an additional level of granularity, split across 10 area types varying in population density from 鈥業nner London鈥� to 鈥楻ural鈥�. Please see TAG unit A5-4 marginal external costs for a detailed definition of the area types and apply the relevant damage costs when both the sector and geographical area type of the emissions are known.

2.3 Part A large industrial processes damage costs

If your policy covers emissions from large industrial processes, you should use the 鈥楶art A sector鈥� damage costs. Go to tables 6 and 7 in annex 1.

鈥楶art A processes鈥� refer to emissions from large industrial processes. Exposure to these emissions is variable, depending on the proximity and size of the population affected and the size of the chimneystack. In the case of听NOx听and听PM, damage costs are provided for a breakdown of Part A sector emissions. This allows a more accurate analysis of impacts linked to air pollutants from large industrial processes.

There are 9 different categories of Part A sector emissions. You can find the relevant damage cost category for your analysis using Table 2. To identify the correct category, use the average population density over which the air pollutant changes are assessed and the height of the stack for the industrial installation.

Table 1: Part A categories

Average population density (persons per km squared)	Stack height is less than or equal to 50m and all small point	Stack Height more than 50m, but less than or equal to 100m	Stack height more than 100m
less than or equal to 250	Category 1	Category 4	Category 7
More than 250, but less than or equal to 1000	Category 2	Category 5	Category 8
More than 1000	Category 3	Category 6	Category 9

The population density has been calculated for different areas for each stack height range. The population density areas are listed in Table 2.

Table 2: Population density areas for Part A categories

Stack Height <= 50 m and all small points	Stack Height > 50,	Stack Height <= 50 m and all small points
11 km x 11 km	21 km x 21 km	31 km x 31 km

2.4 Uncertainty and sensitivity analysis

The estimation of the impacts of air pollution on both health and non-health pathways is inherently uncertain. The methodology for assessing the different impact pathways is based on a number of assumptions around which there is a distribution of probable outcomes.

The IPA methodology (and therefore the damage costs) have been developed based on expert recommendations, in particular from the Committee on the Medical Effects of Air Pollution (COMEAP) and attempts to estimate the impact of air pollution based on the most up to date evidence available.

You should note that the evidence base around air quality impacts is continuously developing and therefore these costs do not necessarily account for the exhaustive list of all the potential health and non-health impacts of air pollution.

The central damage costs represent a best estimation of the current evidence, however there is uncertainty around: the emissions dispersion modelling, the interpretation of changes in air pollution concentrations into impacts and the valuation of those impacts. To account for this uncertainty a sensitivity range has been developed.

The low sensitivity range incorporates the lower bound concentration response function values, lower bound unit values for the valuation of health impacts and a lower level of life years lost assumed from short term exposure. The high sensitivity range incorporates the higher bound concentration response function values, higher bound unit values for the valuation of health impacts, a higher level of life years lost assumed from short term exposure and additional impact pathways.

For more information on the sensitivity range and additional sensitivity analysis conducted on three key parameters, go to the .

2.5 Step-by-step guide

Use this step-by-step guide, along with the听damage costs toolkit, if you want to apply damage costs. A worked example can be found in annex 2.

Step 1: identify and quantify the change in emissions

Estimate the impact on emissions from the change in activity at their source. The relationship between the activity and pollution produced is known as the 鈥榚missions factor鈥�. For example, an emissions factor for road traffic is the amount of pollution produced per vehicle distance travelled.

Estimates of emissions factors are developed by the National Atmospheric Emissions Inventory (NAEI), presented in their听.

Damage costs for particulate matter are expressed in terms of emissions of听PM2.5听(particles of diameter 2.5碌m or less). For some activities it鈥檚 more common for emissions to be expressed in terms of听PM10听(particles of diameter 10碌m or less) so these must be adjusted to听PM2.5 emissions and then monetised using the听PM2.5 damage costs. You can find a list of adjustment factors for different sectors, based on the ratio between these emissions in the听NAEI, in annex 1.

Step 2: Identify which damage cost values to use

Choose whether the national, sector specific or large industrial Part A processes damage costs are most appropriate for your policy.

Step 3: Convert damage cost values to relevant base year prices

The damage cost values presented in annex 1 are in 2025 prices. You must account for inflation by using the Gross Domestic Product (GDP) deflator, adjusting the values to the price base year for the project appraisal (that鈥檚 the year in which all costs and benefits are being accounted).

Step 4: Calculate benefits for each year

Use the inflation adjusted damage costs to estimate the impact of a change in emissions for each year of the appraisal period. Multiply the expected change in emission figures from Step 1 (in tonnes) by the adjusted damage cost figures from step 3 in each year to get the annual benefit.

Step 5: Discount benefits across the period of the policy appraisal and calculate total present value

To calculate the annual present value of air pollution, multiply the undiscounted value of impacts for each year (calculated in Step 4) by the relevant annual discount factor. Discount factor for year t = 1/(1+0.015)*t, where:

• 0.015 is the 1.5% discount rate (in line with HMT鈥檚听Green Book guidance)
• t is the number of years into the future that value is from the base year (year 0)

Present value = valued benefit x discount factor

The base year should be the current year in which the appraisal is being carried out. The discount factor for the base year is 1, and the following year (year 1) the discount factor is 0.985 after discounting at 1.5%鈥�. The total present value is the sum of the present value of impacts in all appraisal years.

Step 6: Sensitivity analysis

In addition to the central damage cost estimates, use low and high damage cost estimates for sensitivity analysis. Repeat steps 3 to 6 using the high and low sensitivity damage cost values to generate present values of impacts for those sensitivities.

3. Activity costs

When you do not know the changes in pollutant emissions but do know the changes in fuel consumption, use 鈥榓ctivity costs鈥� to estimate the impact of air quality.

The activity costs are calculated by combining NAEI听emission factors for听NOx,听PM2.5听and听SO2听with the appropriate damage costs. The total costs summed across the three pollutants calculate the activity cost values for each fuel type.

The activity costs are published by the Department for Energy Security and Net Zero (DESNZ) as part of the听Energy Use and Greenhouse Gas Emissions Supplementary Guidance to the Green Book. The activity costs are listed in 鈥楧ata tables 1 to 19: supporting the toolkit and the guidance鈥�, specifically tables 14 and 15 (note that DESNZ听align the price base with other values within their workbook).

Activity costs are expressed in pence per kilowatt hour (p/KWh) and associated with specific fuel types:

• Electricity
• Gas
• Coal
• Oil
• Biomass
• LPG
• Peat
• Petroleum
• Coke

Data on each fuel type is provided across geographical specifications: National average, Inner conurbation, Urban big, Urban medium, Urban small and Rural)

Activity costs are also provided for the transport sector, expressed in pence per litre consumed (p/litre) by vehicle type:

• Car, petrol
• Car, diesel
• LGV, petrol
• LGV, diesel
• Rigid LGV, petrol
• Articulated HGV, diesel

Data on each vehicle type is provided across geographical specifications: Transport average, Central London, Inner London, Outer London, Inner conurbation, Outer conurbation, Urban big, Urban large, Urban medium, Urban small and Transport rural.

4. Annex 1: 2025 damage costs data

4.1 Damage costs per tonne of emissions data

The following tables show the full set of updated damage cost values, in 2025 prices, alongside the low and high sensitivities. In Tables 4 and 6 the final column also displays the conversion factor required to estimate impacts of听PM10听emissions.

Table 3: national damage costs (2025 prices)

Pollutant emitted	Central damage cost (拢/t)	Damage cost sensitivity range (拢/t): low	Damage cost sensitivity range (拢/t): high
NOx	拢10,193	拢1,671	拢34,546
SO2	拢26,193	拢9,158	拢72,022
NH3	拢9,900	拢3,376	拢27,868
VOC	拢150	拢90	拢277
PM2.5	拢114,411	拢40,026	拢371,654

Table 4: PM听source sector damage costs (2025 prices)

Pollutant emitted	Central damage cost (拢/t)	Damage cost sensitivity range (拢/t): low	Damage cost sensitivity range (拢/t): high	PM2.5/PM10听conversion factor
PM2.5听industry (area)	拢170,576	拢61,511	拢787,110	0.220
笔惭2.5听肠辞尘尘别谤肠颈补濒	拢146,671	拢50,747	拢404,555	0.929
笔惭2.5听诲辞尘别蝉迟颈肠	拢109,172	拢37,747	拢297,946	0.977
笔惭2.5听蝉辞濒惫别苍迟蝉	拢182,830	拢63,652	拢554,483	0.633
PM2.5听road transport	拢121,222	拢42,305	拢380,527	0.564
笔惭2.5听补颈谤肠谤补蹿迟	拢146,743	拢51,084	拢444,486	0.636
笔惭2.5听辞蹿蹿谤辞补诲	拢89,066	拢30,825	拢246,788	0.909
笔惭2.5听谤补颈濒	拢111,755	拢38,690	拢311,294	0.888
笔惭2.5听蝉丑颈辫蝉	拢65,693	拢22,723	拢180,426	0.947
笔惭2.5听飞补蝉迟别	拢106,862	拢36,976	拢295,121	0.923
笔惭2.5听补驳谤颈肠耻濒迟耻谤别	拢35,416	拢12,934	拢184,157	0.177
笔惭2.5听辞迟丑别谤	拢149,541	拢51,762	拢415,338	0.899
PM2.5听road transport central London	拢648,110	拢226,292	拢2,048,400	0.551
PM2.5听road transport inner London	拢628,530	拢219,583	拢2,002,690	0.537
PM2.5听road transport outer London	拢353,225	拢123,383	拢1,123,061	0.541
PM2.5听road transport inner conurbation	拢253,612	拢88,530	拢798,916	0.557
PM2.5听road transport outer conurbation	拢159,099	拢55,524	拢499,532	0.563
PM2.5听road transport urban big	拢152,869	拢53,356	拢480,719	0.561
PM2.5听road transport urban large	拢122,884	拢42,888	拢386,116	0.562
PM2.5听road transport urban medium	拢99,639	拢34,775	拢313,066	0.562
PM2.5听road transport urban small	拢84,998	拢29,664	拢266,921	0.563
PM2.5听road transport rural	拢49,192	拢17,163	拢153,912	0.570
笔惭2.5听谤补颈濒 transport central London	拢558,441	拢193,113	拢1,527,561	0.966
笔惭2.5听谤补颈濒 transport inner London	拢709,957	拢245,507	拢1,941,808	0.966
笔惭2.5听谤补颈濒 transport outer London	拢456,691	拢157,929	拢1,249,411	0.965
笔惭2.5听谤补颈濒 transport inner conurbation	拢266,139	拢92,033	拢728,001	0.966
笔惭2.5听谤补颈濒 transport outer conurbation	拢145,097	拢50,181	拢397,628	0.957
笔惭2.5听谤补颈濒 transport urban big	拢158,795	拢54,916	拢434,845	0.961
笔惭2.5听谤补颈濒 transport urban large	拢119,759	拢41,449	拢332,076	0.906
笔惭2.5听谤补颈濒 transport urban medium	拢89,462	拢30,949	拢246,241	0.938
笔惭2.5听谤补颈濒 transport urban small	拢73,313	拢25,389	拢205,259	0.868
笔惭2.5听谤补颈濒 transport rural	拢45,868	拢15,892	拢129,411	0.839
PM2.5 domestic central London	862,547	拢298,193	拢2,348,976	0.987
PM2.5 domestic inner London	拢733,939	拢253,754	拢2,001,566	0.980
PM2.5 domestic outer London	拢394,288	拢136,326	拢1,075,708	0.978
PM2.5 domestic inner conurbation	拢292,459	拢101,120	拢798,172	0.977
PM2.5 domestic outer conurbation	拢182,873	拢63,230	拢499,094	0.977
PM2.5 domestic urban big	拢156,677	拢54,173	拢427,606	0.977
PM2.5 Domestic urban large	拢143,176	拢49,504	拢390,775	0.976
PM2.5 domestic urban medium	拢107,392	拢37,132	拢293,097	0.977
PM2.5 domestic urban small	拢86,151	拢29,788	拢235,129	0.976
PM2.5 domestic rural	拢50,279	拢17,384	拢137,214	0.977

Table 5: NOx听source sector damage costs (2025 prices)

Pollutant emitted	Central damage cost (拢/t)	Damage cost sensitivity range (拢/t): low	Damage cost sensitivity range (拢/t): high
NOx听industry (area)	拢12,228	拢1,868	拢41,837
狈翱虫听肠辞尘尘别谤肠颈补濒	拢21,315	拢2,747	拢74,389
狈翱虫听诲辞尘别蝉迟颈肠	拢18,998	拢2,523	拢66,089
狈翱虫听蝉辞濒惫别苍迟蝉	拢21,796	拢2,794	拢76,114
NOx听road transport	拢13,631	拢2,004	拢46,863
狈翱虫听补颈谤肠谤补蹿迟	拢17,172	拢2,346	拢59,547
狈翱虫听辞蹿蹿谤辞补诲	拢11,431	拢1,791	拢38,982
狈翱虫听谤补颈濒	拢13,241	拢1,966	拢45,465
狈翱虫听蝉丑颈辫蝉	拢3,623	拢1,036	拢11,011
狈翱虫听飞补蝉迟别	拢11,422	拢1,790	拢38,949
狈翱虫听补驳谤颈肠耻濒迟耻谤别	拢4,724	拢1,142	拢14,956
狈翱虫听辞迟丑别谤	拢4,442	拢1,115	拢13,945
NOx听road transport central London	拢72,737	拢7,721	拢258,606
NOx听road transport inner London	拢71,618	拢7,613	拢254,598
NOx听road transport outer London	拢40,048	拢4,559	拢141,501
NOx听road transport inner conurbation	拢28,927	拢3,483	拢101,658
NOx听road transport outer conurbation	拢18,365	拢2,462	拢63,823
NOx听road transport urban big	拢17,655	拢2,393	拢61,279
NOx听road transport urban large	拢14,307	拢2,069	拢49,286
NOx听road transport urban medium	拢11,630	拢1,810	拢39,695
NOx听road transport urban small	拢10,012	拢1,654	拢33,899
NOx听road transport rural	拢5,944	拢1,260	拢19,323
狈翱虫听谤补颈濒 transport central London	拢83,509	拢8,764	拢297,196
狈翱虫听谤补颈濒 transport inner London	拢80,591	拢8,483	拢286,738
狈翱虫听谤补颈濒 transport outer London	拢51,611	拢5,681	拢182,916
狈翱虫听谤补颈濒 transport inner conurbation	拢31,508	拢3,737	拢110,898
狈翱虫听谤补颈濒 transport outer conurbation	拢17,233	拢2,357	拢59,752
狈翱虫听谤补颈濒 transport urban big	拢18,074	拢2,439	拢62,763
狈翱虫听谤补颈濒 transport urban large	拢14,422	拢2,087	拢49,677
狈翱虫听谤补颈濒 transport urban medium	拢10,937	拢1,750	拢37,191
狈翱虫听谤补颈濒 transport urban small	拢8,867	拢1,551	拢29,774
狈翱虫听谤补颈濒 transport rural	拢5,960	拢1,271	拢19,355
狈翱虫听诲辞尘别蝉迟颈肠 central London	拢92,180	拢9,612	拢328,231
狈翱虫听诲辞尘别蝉迟颈肠 inner London	拢87,005	拢9,113	拢309,690
狈翱虫听诲辞尘别蝉迟颈肠 outer London	拢53,260	拢5,849	拢188,798
狈翱虫听诲辞尘别蝉迟颈肠 inner conurbation	拢34,167	拢4,003	拢120,397
狈翱虫听诲辞尘别蝉迟颈肠 outer conurbation	拢22,755	拢2,900	拢79,511
狈翱虫听诲辞尘别蝉迟颈肠 urban big	拢20,114	拢2,645	拢70,045
NOx听Domestic urban large	拢17,188	拢2,363	拢59,561
狈翱虫听诲辞尘别蝉迟颈肠 urban medium	拢13,097	拢1,968	拢44,902
狈翱虫听诲辞尘别蝉迟颈肠 urban small	拢10,618	拢1,730	拢36,020
狈翱虫听诲辞尘别蝉迟颈肠 rural	拢6,403	拢1,323	拢20,916

Table 6: PM听Part A sector damage costs (2025 prices)

Pollutant emitted	Central damage cost (拢/t)	Damage cost sensitivity range (拢/t): low	Damage cost sensitivity range (拢/t): high	PM2.5/PM10听conversion factor
PM2.5听Part A category 1	拢12,917	拢4,478	拢36,781	0.807
PM2.5听Part A category 2	拢59,137	拢20,486	拢166,364	0.850
PM2.5听Part A category 3	拢230,713	拢80,004	拢659,233	0.795
PM2.5听Part A category 4	拢5,329	拢1,848	拢15,289	0.782
PM2.5听Part A category 5	拢8,098	拢2,810	拢23,389	0.761
PM2.5听Part A category 6	拢25,534	拢8,857	拢73,279	0.781
PM2.5听Part A category 7	拢1,481	拢513	拢4,234	0.792
PM2.5 Part A category 8	拢4,177	拢1,450	拢12,082	0.757
PM2.5 Part A category 9	拢9,173	拢3,195	拢28,040	0.616

Table 7: NOx听Part A sector damage costs (2025 prices)

Pollutant emitted	Central damage cost (拢/t)	Damage cost sensitivity range (拢/t): low	Damage cost sensitivity range (拢/t): high
NOx听Part A category 1	拢3,612	拢1,035	拢10,972
NOx听Part A category 2	拢4,896	拢1,159	拢15,572
NOx听Part A category 3	拢10,258	拢1,678	拢34,779
NOx听Part A category 4	拢3,097	拢985	拢9,125
NOx听Part A category 5	拢3,532	拢1,027	拢10,685
NOx听Part A category 6	拢5,255	拢1,194	拢16,855
NOx听Part A category 7	拢2,961	拢972	拢8,639
NOx听Part A category 8	拢3,364	拢1,011	拢10,083
NOx听Part A category 9	拢3,650	拢1,038	拢11,105

4.2 Activity costs data

For activity costs data refer to 听鈥楨nergy Use and Greenhouse Gas Emissions Supplementary Guidance to the Green Book鈥�.

The activity costs data is within 鈥楧ata tables 1 to 19: supporting the toolkit and the guidance鈥�, specifically tables 14 and 15 (note that DESNZ align the price base with other values within their workbook).

5. Annex 2: Damage costs worked example

This section uses a hypothetical policy measure to show how the impact of听NOx听is calculated using damage costs per tonne of emissions.

5.1 The hypothetical policy

A measure introducing more efficient NOx controls from vehicles and applied nationally, where:

• one of the expected benefits of implementing this measure is the reduction of听NOx听emissions
• this measure is being assessed for 10 years, with the first year of impacts in 2026
• the scheme is expected to reduce emissions of听NOx听by 12 tonnes per year until 2028 and 3 tonnes per year thereafter, compared to a 鈥榙o nothing鈥� scenario
• the price base year for appraisal is 2023
• the discounting year is 2026

5.2 Step 1: identify and quantify change in emissions

Table 8 shows the level of change that is expected from this hypothetical policy.

If you鈥檙e quantifying the impacts of听PM10, convert your emissions to听PM2.5听using the conversion factors set out in听Annex A.

Table 8: level of change in听NOx听emissions

Year	NOx听emissions reduction (tonnes)
2026	12
2027	12
2028	12
2029	3
2030	3
2031	3
2032	3
2033	3
2034	3
2035	3

5.3 Step 2: identify which damage cost values to use

For this example, as the policy is impacting vehicles and applied nationally, we鈥檝e used the听NOx听road transport damage cost of 拢13,631 is used.

5.4 Step 3: convert听NOx听damage costs to base year

The price base year for the appraisal is 2023 in this case, so the damage costs will need to be adjusted to the new price base using听GDP听deflators (note these are likely to change over time, see听鈥楢nnual Parameters鈥� tab in the TAG Data Book).

Multiplying the ratio of the index values for 2023 (100) and 2025 (107.14) - so, 100.00 / 107.14 = 0.93 - by the damage cost value, gives a rebased value of 拢12,723.

Table 9: change in emissions (t), appropriate damage cost (拢) and rebased damage cost

Year	NOx听emission reduction (tonnes)	NOx national average road transport damage costs, central (2025 prices)	Rebased to 2023 prices
2026	12	拢13,631	拢12,723
2027	12	拢13,631	拢12,723
2028	12	拢13,631	拢12,723
2029	3	拢13,631	拢12,723
2030	3	拢13,631	拢12,723
2031	3	拢13,631	拢12,723
2032	3	拢13,631	拢12,723
2033	3	拢13,631	拢12,723
2034	3	拢13,631	拢12,723
2035	3	拢13,631	拢12,723

5.5 Step 4: calculate benefits for each year

Multiply the price year adjusted damage cost values by the change in emissions (tonnes) for the corresponding years.

Table 10: calculating the total undiscounted benefit of the change in emissions

Year	NOx听emission reduction (tonnes)	NOx national average road transport damage costs, central (2023 prices)	Total undiscounted benefit
2026	12	拢12,723	拢152,676
2027	12	拢12,723	拢152,676
2028	12	拢12,723	拢152,676
2029	3	拢12,723	拢38,169
2030	3	拢12,723	拢38,169
2031	3	拢12,723	拢38,169
2032	3	拢12,723	拢38,169
2033	3	拢12,723	拢38,169
2034	3	拢12,723	拢38,169
2035	3	拢12,723	拢38,169

5.6 Step 5: discount benefits across the period of the policy appraisal to calculate total present value

Table 11 shows the present values for the hypothetical policy scenario, calculated using the 1.5% discount rate (in line with HMT鈥檚听Green Book guidance).

The total present value of air quality impacts can then be calculated as the sum of present values across the appraisal period. For this example, the central estimate of the present value is 拢621,217 over the 10-year appraisal period.

Table 11: total discounted benefits of the change in emissions

Year	NOx听emission reduction (tonnes)	Total undiscounted benefit	Discount Factor	Total discounted benefit
2026	12	拢152,676	1	拢152,676
2027	12	拢152,676	0.985	拢152,420
2028	12	拢152,676	0.971	拢148,197
2029	3	拢38,169	0.956	拢36,502
2030	3	拢38,169	0.942	拢35,962
2031	3	拢38,169	0.928	拢35,431
2032	3	拢38,169	0.915	拢34,907
2033	3	拢38,169	0.901	拢34,391
2034	3	拢38,169	0.888	拢33,883
2035	3	拢38,169	0.875	拢33,382
Total	57	拢725,211	听	拢695,751

5.7 Step 6: sensitivity analysis

The sensitivity range can be calculated using the same procedure but applying the low and high damage costs.

For the hypothetical policy, the high estimate of the present value is 拢2,391,900 and the low estimate of the present value is 拢102,260.

6. Annex 3: Health metrics

6.1 Health metrics description

This section discusses health听outcomes which capture the underlying health effects of air pollution in non-monetary terms.

These metrics represent听the听intermediate听health听outcomes听estimated as part of (or underpinning) the听damage cost calculations.听As with the damage cost values, the health metrics and the pathways captured are derived from the Impact Pathway Approach and can be broadly split into 3 metrics:

• Mortality 鈥� Life Years Lost (LYL) per tonne of emissions听听

• Morbidity 鈥� Quality-Adjusted-Life Years (QALYs) lost听per tonne of emissions听听

• Morbidity听鈥撎齆umber of hospital admissions per tonne of emissions听听

In section 6.2, data is presented for each of the above metrics for the national damage cost values with separate tables presenting low and high estimates based on the sensitivity range. Please note that some of the hospital admission values are negative due to pathways where increased pollutant emissions result in reductions of ozone concentrations and consequently reduced estimated admissions.

These health metrics can be used for听the purposes of a simplified assessment听to approximate the听health impacts of听marginal changes in听air pollution in the absence of concentration听data and provide an evidence-based narrative to听accompany听the valuation of air pollution impacts using damage costs.

Please note there are multiple steps between these health metrics and their corresponding damage costs values, as the monetised damage costs also include environmental, materials and productivity pathways and apply discounting techniques.

For further information or any questions about these health metrics and how they should be used, email igcb@defra.gov.uk.

6.2 Health metrics data

Table 12: intermediate health metrics associated with national damage costs (central)

Pollutant emitted	LYL / tonne	QALYs / tonne	Hospital admissions / tonne
NOx	0.11	0.068	0.0044
SO2	0.31	0.14	0.0069
NH3	0.11	0.049	0.0025
VOC	0.00015	-	0.0020
PM2.5	1.4	0.60	0.030

Table 13: intermediate health metrics associated with national damage costs (low sensitivity)

Pollutant emitted	LYL / tonne	QALYs / tonne	Hospital admissions / tonne
NOx	0.043	0.0092	0.0026
SO2	0.24	0.038	-0.0045
NH3	0.086	0.014	-0.0016
VOC	0.000027	-	0.00080
PM2.5	1.0	0.17	-0.020

Table 14: intermediate health metrics associated with national damage costs (high sensitivity)

Pollutant emitted	LYL / tonne	QALYs / tonne	Hospital admissions / tonne
NOx	0.21	0.22	0.012
SO2	0.35	0.47	0.022
NH3	0.13	0.18	0.0081
VOC	0.00038	-	0.0034
PM2.5	1.5	2.6	0.098