5.1 |
Model to Estimate Economic Cost of Morbidity
5.1.1 |
Using COI Estimates
5.1.1.1 |
The dollar value of morbidity is calculated from the data collected. For COI estimates, they are based on values associated with cost of illness, i.e., direct and indirect cost, such as, medical expenses (including self-medication and doctor consultation) and productivity loss, compensation schemes and awards. |
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5.1.1.2 |
For this study, the economic costs of health effects due to air pollution will be limited to hospital treatment as in-patients and mortality (upon which CUHK preformed the statistical analysis of association between health effects and air pollution). |
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5.1.1.3 |
The models with specific air pollutants for hospital admissions indicating the relative risks (RR) with 95% confidence intervals (95% CI) (by CUHK/HKU) is the basis for estimating the monetary value of the health outcome. Since the actual number of admission (as health outcome) resulting from pollution effect is known (from the available model), the cost of illness can be estimated by considering the factors concerned. |
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5.1.1.4 |
The COI estimated is then used as an input for estimating the economic cost as presented in the following model:
E = b(dj) * COI(dj) * { RR(pi, dj) -1 }
where,
E |
= |
economic cost of morbidity by hospital admission |
b(dj) |
= |
actual hospital admission and out-patient doctor consultation due to a particular disease dj |
dj |
= |
diseases (e.g., respiratory or circulatory diseases) |
COI |
= |
estimated cost of illness related to hospital admissions and out-patient treatment due to dj |
RR |
= |
Relative risk for morbidity - pi, dj (air pollutant & disease specific in respective order) |
pi |
= |
air pollutants (e.g. NO2, SO2, RSP, and O3) |
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5.1.1.5 |
In practice, COI is first computed based on the statistics on hospital admission and the result obtained is subsequently applied in the model. In this way, the economic cost associated with hospital admission is the product of the total cost of illness and the relative risk (RR) of admission. RR has already been estimated in a separate study on the short-term health impact of air pollution in Hong Kong (see CUHK, 1997; HKU, 1998). It is obtained by multiplying the exponential of the regression coefficient by the defined increase in the pollutant. |
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5.1.1.6 |
For the calculation of COI for morbidity (where hospital admission is expected to be the key cost component), we have identify the cost components (direct and indirect cost related to the illness) as follows:
Cost components (COI estimates):
Direct cost |
Indirect cost |
Self medication:
Buying medication over the counter
Defensive expenditure e.g., special diet, equipment
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Output (earning) loss:
Off-work day (not serious enough for admission)
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Treated as Out-patient:
Doctor consultation - GOPC (12% of all cases)
GOPC charges (registration fee at HK$34)
Subsidies for GOPC cases (HK$141 per case)
Doctor consultation - private (88% of all cases)
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Off-work day (average no. of days hospitalised for admission cases and 1 day off for non hospitalised out-patient cases)
- assume no accompanying cost
- assume accompanying cost
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Hospital Admission:
Average length of hospital stay
Room rate per day
Subsidies involved
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5.1.1.7 |
The 1995 dataset has been used instead of 1994 dataset. COI for respiratory diseases and cardiovascular diseases are calculated separately. For the statistics on the number of hospital admissions in 1995, distribution by age groups are used and together with the average length of hospital stay, both direct and indirect cost of illness are estimated. |
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5.1.1.8 |
The use of the HA statistics is consistent with the CUHK study. The overall employment earnings at HK$10,000 per month has been used to estimate indirect cost. This statistics is provided by the Census and Statistics Department. This is the latest figure available (1996 and 1997) and it is compiled from the General Household Survey by occupation of main employment. |
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5.1.1.9 |
Since the very young and the elderly are more likely to require someone else to assist them especially when their symptoms are severe enough to warrant hospital admission, estimates with accompanying cost are more representative than those without accompany cost. |
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5.1.1.10 |
Direct cost is largely the inpatient charges which include maintenance fee. According to the Hong Kong Government's charge rate, the entitled person is required to pay a sum of HK$68 as the maintenance fee (includes charges for clinical, biochemical and pathological investigations, vaccines and general nursing but excludes consultation, diagnostic imaging etc.). For the same health care services, the non entitled person will have to pay HK$3,130 (Special Supplement No.4, 1996)8. We use the difference between this amount (HK$3,130) and the daily room charge of HK$68 as the subsidy to the entitled person (i.e., HK$3,062). The sum of HK$3,130 would therefore be the public ward maintenance fee which includes charges for clinical, biochemical and pathological investigations (including consultation, diagnostic imaging and other examinations), vaccines and general nursing, where such examination or treatment are necessary, and medicines within the scale provided at the hospitals (S. S. No.4 to Gazette No. 44/1996, Para.2.0). |
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5.1.1.11 |
Indirect cost is made up of earnings loss. For the calculation, we assume that the average length of hospital admission is also the number of days work has been affected due to sickness. In this case, we assume employment outside of the house is affected only when individual is being admitted to hospital. In addition, there is a subdivision for this particular cost area. For some persons, we assume the individuals do not require the assistance of others, however, some categories, often the young and old tend to require accompanying cost. We treat those aged 14 and below and those above 65 to be those where there will be accompanying. The cost is estimated on a per day basis from the known monthly overall wage for Hong Kong (statistics obtained from the Census and Statistics Department). |
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5.1.1.12 |
Medical insurance payments can be treated as subsidies on medical expenses. Even if the victim need not pay the full medial bill, the payment by insurance company constitutes a cost to the society because resources are limited and once it is applied in one area, other area would have a lesser share. Since detailed information on individuals'medical insurance coverage is not readily available, and so long as we avoid double counting of the cost variables, we deem it acceptable to skip the differences due to insurance payment by employing companies. |
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5.1.1.13 |
The key results of the COI estimates for respiratory and cardiovascular diseases are presented in Appendix 4a and 4b. As the economic evaluation of morbidity based on hospital admission alone is likely to underestimate the health impact of air pollution, we have taken into account the total number of out-patient attendances. |
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5.1.1.14 |
Doctor consultation fee includes both public GOPCs and General Practitioner (GP) categories. The data for GOPC attendances are available from the Department of Health Survey (DH, 1997). The information provided by the DH also specified that the GOPC attendances at public out-patient clinics only made up 12% of the market share. Hence, we have used the statistics given to estimate the remaining 88% GOPC attendances. |
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5.1.1.15 |
The statistics on GOPC are the survey findings on "Disease Surveillance at General Out-patient Clinics" conducted by the Department of Health over one week (18 - 24 August) in 1995. These findings could be subject to seasonal effect and hence might not represent the characteristics of the patient attending GOPC in a longer period. Also, the survey covered patients attending public day GOPCs for doctor consultation only. Patients attending non-public, evening, Sunday and public holiday and mobile clinics were not included in the survey. |
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5.1.1.16 |
The economic evaluation of the GOPC attendances offered only broad estimates since it is difficult if not impossible to determine that the pre-disposing factor of the ailment is an associated increase in air pollution. The symptoms of illnesses treated at GOPCs tend to be less severe. Had the two previous statistical analysis also considered the impact of the criterion air pollutants on out-patient cases, we would have a RR for the GOPCs. In this study, we assume all the out-patient cases treated for respiratory diseases and cardiovascular diseases suffered the impact of air pollution. We also assume that every clinic visit will incur an average of one day of work loss (based on the average wage (i.e., HK$120,000/365). |
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5.1.1.17 |
The results of COI (Appendix 4) are applied to the valuation of health impacts together with the relative risks estimated previously by CUHK (September, 1997) and HKU (Jan., 1998). It is considered necessary to take into consideration both hospital admissions and GOPCs attendances in the broad category of morbidity. |
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5.1.1.18 |
Details of the workings on economic valuation of morbidity using the relative risks for 50ug/m3 increase in the levels of NO2, SO2, RSP and O 3 are shown in Appendix 5a (by respiratory and cardiovascular diseases) and Appendix 5b (combined respiratory and cardiovascular diseases). |
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5.1.1.19 |
The set of RR ( Table 1) is taken from the follow-up study of health impacts by HKU (Jan., 1998).
Table 1: |
Relative risks (RR) and 95% confidence interval (95% CI) for 50 ug/m3 increase in the concentration of air pollutants for hospital admissions of respiratory and cardiovascular diseases: |
Diseases/Pollutants |
Respiratory |
Circulatory |
Respiratory & Circulatory |
NO2 |
1.08 |
1.08 |
1.07 |
SO2 |
1.03 |
1.05 |
1.04 |
RSP |
1.05 |
1.03 |
1.04 |
O3 |
1.10 |
1.07 |
1.07 |
Source: HKU (Jan., 1998)
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5.1.1.20 |
The results of the valuation on morbidity based on respiratory and cardiovascular diseases and combined respiratory and cardiovascular diseases are summarised below (Table 2):
Table 2: |
Results of Economic Valuation of Morbidity Using COI Estimates: |
Economic cost (in HK$ million) |
Relative Risk 50ug /m3 |
Respiratory Diseases |
Cardiovascular Diseases |
Combined Respiratory & Cardiovascular |
NO2 |
522.20 |
451.90 |
852.34 |
SO2 |
195.82 |
282.44 |
487.05 |
RSP |
326.37 |
169.46 |
487.05 |
O3 |
652.75 |
395.41 |
852.34 |
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5.1.1.21 |
In comparing the economic cost of the impact of air pollution on respiratory and cardiovascular disease, RSP accounted for a higher economic cost in respiratory diseases than in cardiovascular diseases. This is probably the result of a higher incidence of respiratory illnesses caused by RSP. |
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5.1.1.22 |
Comparison is also made between direct cost of COI estimated and public expenditure on medical and health services. |
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5.1.1.23 |
For the purpose of comparing public expenditure on health, especially health expenses incurred by HA and the Department of Health, the direct cost component of COI estimates is extracted from this study. |
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5.1.1.24 |
We shall present the economic valuation of direct cost as follows:
Category I: |
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Category II: |
By type of diseases:
- respiratory diseases
- cardiovascular diseases
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By combined respiratory and cardiovascular diseases: |
1. Hospital admissions |
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1. Hospital admissions |
2. GOPC and private doctor consultation |
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2. GOPC and private doctor consultation |
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5.1.1.25 |
The results of direct cost estimated are presented in Appendix 5c(i) and 5c(ii).
The direct cost estimated based on respiratory and cardiovascular diseases in separate categories (see Appendix 5c(i)) and as combined diseases (Appendix 5c(ii)) were presented but the estimates in the latter were used for the purpose of comparison. The direct cost on an annual basis ranged from HK$255.98 million to HK$447.97 million. The annual expenditure of the Department of Health (DH) and HA were HK$2,283 and HK$18,922 respectively for 1995/1996 (see Department of Health, Annual Report 1995/96; Census and Statistics Department, 1997). The direct cost calculated is equivalent to almost 20% of DH's expenditure for 1995/1996 (at the upper limit) whereas it is only equivalent to 2.37% of HA's expenditure over the same period. This can be explained by the relative size of HA expenditure compared to that of DH (an eight-fold increase). Details are shown in Appendix 5d.
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5.1.2 |
Economic Cost of Morbidity Calculated Using WTP Estimates
5.1.2.1 |
WTP estimates go beyond the lost of earnings and medical costs. However, WTP values are mainly obtained from contingent valuation and they are grouped as follows:
WTP to avoid the symptoms of the diseases concerned:
Light symptoms without the need for doctor consultation
One symptom day suffered (descriptions of symptoms provided)
Seven symptom day suffered
WTP to avoid hospitalisation specific to the diseases:
One day of hospitalisation
One week of hospitalisation
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5.1.2.2 |
The appropriate value from the FG data set is summarised in Table 3 below:
Table 3 |
Summary of WTP Estimates From the Contingent Valuation on Morbidity |
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WTP |
1 week symptom but no hospital admission |
1day hospitalisation |
Respiratory diseases |
Min |
30 |
20 |
Max |
10,000 |
20,000 |
SD |
1,825.19 |
3,664 |
Average |
735.52 |
1,137 |
Cardiovascular diseases |
Min |
150 |
50 |
Max |
15,000 |
20,000 |
SD |
3,170.09 |
3,981 |
Average |
1,517.59 |
1,736 |
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5.1.2.3 |
In substituting the WTP values to estimate the economic cost of morbidity, we use a similar equation to the one used for COI estimates for hospital admissions. COI input is substituted with WTP. The model is shown as follows:
E = [ b(dj) * ( RR(pi, dj) -1) ] * WTP(dj)
where,
E |
= |
economic cost of morbidity (by hospital admission & out-patient attendances) |
b |
= |
actual hospital admission and out-patient doctor consultation of a particular illness dj |
dj |
= |
illness (e.g., respiratory, circulatory diseases) |
RR |
= |
Relative risk for morbidity due to (pi, dj) (available from study by HKU) |
pi |
= |
air pollutants (e.g. NO2, SO2, RSP, and O3) |
WTP |
= |
estimated monetary value WTP to avoid dj |
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5.1.2.4 |
The "average" WTP value to avoid a day of hospital admission is taken into account. In addition, the average willingness to pay by individuals'to avoid the symptoms during the disease occurrence (non hospitalised cases) is also considered in the calculation. This average bid for 7-symptom days for cases without hospital admission is obtained from the FG survey. Details of the calculations are presented in Appendix 6(i) and Appendix 6(ii). The former shows estimates of the costs based on respiratory diseases and the latter shows estimates for cardiovascular diseases. According to Chestnut (1995), subsidy may be considered under certain circumstances 1. In this study, we have estimated the economic cost with an element of subsidy in the willingness to pay estimates for morbidity. We considered WTP values by the individuals in the FG group understated and this is probably for reason that they left out the subsidy by the public sector. |
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5.1.2.5 |
The results of the economic cost for total morbidity (respiratory and cardiovascular diseases) are presented in Appendix 7. |
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5.1.2.6 |
Appendix 7 presents the calculation of the total economic cost with the relative risks available from HKU study. The working is similar to the calculation using the COI estimates. |
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5.1.2.7 |
The results of monetary valuation by respiratory diseases and cardiovascular diseases (as two separate diseases and as combined respiratory and cardiovascular diseases) are presented in Appendix 7. |
1Chestnut recommends that for a comprehensive measure of WTP, the "share cost" should be added to individual WTP. He argues that financial costs of health effects not always borne by the individual but are shared through health insurance and public health care subsidies. In some instances therefore empirical estimates of WTP to avoid or reduce health effects may not fully reflect these shared costs. The incidence Chestnut is referring to is probably valid in the case of Hong Kong where the room rate for hospital admission is relatively low and a large proportion of the focus group members indicated that they were willing to pay round about the amount of this fee rather than the subsidy which is as much as 40 times the fee payment.
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5.2 |
Model to Estimate Economic Cost of Mortality
5.2.1 |
Cost of Illness (COI) Approach to Value Life (Mortality)
5.2.1.1 |
Cost of illness approach has been the prevailing method used to value life up until the recent years although in practice, it is the economists who tend to favour the WTP method whereas non economists (e.g., engineers and health professionals) may continue to use the human capital calculations (using COI approach) (Haight, 1994)9. |
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5.2.1.2 |
The human capital approach is age-specific and it measures the value of individual's life to society, i.e., future production potential. It is usually calculated as the present discounted value of expected labour earnings. The standard approach assumes a zero value for persons without labour income. However, the choice of an appropriate social discount rate to convert future earnings into present values is still unresolved. Different discount rates will provide different present value of future earnings. The value is significantly bigger for low discount rate. The rate of discount recommended by the US Office of Management and Budget is 10% (Landefeld & Seskin, 1982)10. This represents an estimate of the average rate of return on private investment before taxes and after inflation. |
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5.2.1.3 |
In order to calculate the value of a statistical life (VSL), we need to know the life expectancy, labour force participation and projected earnings. The statistical value of a life year is the aggregate of all the monthly earnings for the year (monthly earnings multiply by 12). The estimated capitalised lifetime earnings is thus the VSL. For example, if a fresh graduate were to enter the labour market at the age of 23, his/her capitalised value would be calculated based on the average earnings over his paid employment period assuming the person would work until his/her retirement age. For example, a in the US, a 39-year period is used. |
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5.2.1.4 |
We shall use the net present value model for calculating the capitalised earnings. We assume the individual is healthy and earning an income (here, income is derived from labour of the individual before tax payments). For the calculation, we are required to consider the net present value of a stream of earnings received over the employment period, assuming retirement is at age 65, thus, a period of about 40 years may be considered. The earnings takes into account tax payment. The reported earnings is generally made in constant or base year dollars. It is necessary to convert the nominal discount rate to a real rate by an adjustment for inflation. |
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5.2.1.5 |
For example, if we were to estimate the net present value (NPV) of capitalised earnings for a fresh graduate, we may use the real dollar value (at constant price) instead of the nominal value and apply a discount rate. |
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5.2.2 |
WTP Approach to Value Loss of Life
5.2.2.1 |
For this, we use a change in risk that will affect loss of life. The revealed-preference through the WTP method is an alternative to human capital (COI) approach. It is used to measure the private valuation individuals place on small reductions in the risk (probability) of death (i.e., m/^ p where, m is the WTP for the benefit of living and ^ p is change in risk). The result obtained indicates the value per statistical life. |
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5.2.2.2 |
The median value indicated by individuals' willingness to pay (from the FG questionnaire survey) will be retrieved from the dataset compiled (see questionnaire which refers to a small change in mortality - risk reduction). |
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5.2.2.3 |
The results obtained for the VSL using COI and WTP approaches will be discussed here. We shall begin with the COI estimates of the VSL. |
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5.2.2.4 |
The overall earning for the Hong Kong population is estimated at HK$10,000 (in 1997 prices) (see Census & Statistics Department (C&SD), correspondence where C&SD provided EHS statistics from Household Survey by major employment categories, 1998). |
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5.2.2.5 |
For this purpose, we shall use a discount rate which reflects the individual rate of time preference. The "Yield of Exchange Fund Bills and Notes" for a 10-year period at around 7% is used (see HKMA, Monthly Statistical Bulletin, July, 1997). |
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5.2.2.6 |
The calculation performed is based on the overall employment earnings for Hong Kong 1996/1997 at HK$10,000 per month or HK$120,000 per annum (Census and Statistics Department, 1998). The stream of earnings discounted over 40 years period is HK$1,597,579. This means that the value of a statistical life is about HK$1.60 million. Details of the calculations performed on the stream of income at a discount rate of 7.0% are shown in Appendix 8a. |
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5.2.2.7 |
According to the data by Department of Health, the total number of deaths for all age groups due to respiratory diseases and cardiovascular diseases were 5,821 and 8,748 respectively for 1995/96. |
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5.2.2.8 |
The total number of deaths (for 1995/96) is taken into account in the calculation. The capitalised earnings over a span of 40 years, based on a 7.0% discount rate (as the opportunity cost of capital) is used in the calculations. Estimation of capitalised earnings are shown in Appendix 8(i) and Appendix 8(ii). |
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5.2.2.9 |
The statistics show that the largest number of deaths occurred in the age group "65 and above" and it is true for both respiratory diseases and circulatory diseases and they accounted for 86.75% and 83.04% respectively. Had the calculations been limited to only those from age groups within the categories of working age population (inclusive of age groups "15-24" and "55-64"), the number of deaths accounted for about 13% and 16% of deaths from respiratory and circulatory diseases respectively. Details of the calculations are presented in Appendix 8c(i) and Appendix 8c(ii) (which show the VSL estimated by deaths from respiratory and cardiovascular diseases). |
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5.2.2.10 |
For the WTP estimates, we use the dataset from the focus group survey. For a risk reduction of death from respiratory diseases by 0.01%, the median value individuals were prepared to pay is HK$500. Thus, the implied value per statistical life (VSL) is HK$5 million. |
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5.2.2.11 |
The median of individuals' WTP to reduce the risk of cardiovascular diseases by the same amount (i.e. 0.01%) is also HK$500. The VSL is therefore the same as that for respiratory diseases (i.e., HK$ 5 million). This median value is then used to estimate VSL based on the actual number of deaths. |
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5.2.2.12 |
In the calculation of VSL using WTP estimates, we take into account age factor. For working purposes, we estimated the mean age of all deaths by the diseases concerned. For simplicity, the victims of air pollution are divided into two broad categories (age below/ age above 76 and 75 for respiratory and cardiovascular diseases respectively). For the group below the mean age, we estimated the VSL of premature deaths by discounting the values based on WTP estimates over a 40-year period (similar to the estimation applied to COI). However, for age group beyond the mean age, their willingness to pay to change the risk of death would not be discounted to reflect that unlike the younger population, they can realise the value in the immediate future. Details of the estimations are shown in Appendix 8b. |
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5.3 |
Substituting VSL Obtained Into the Valuation Model
5.3.1 |
For the cost calculation for mortality, we are required to refer to the relative risks and the following is the Relative Risks (RRs) with 95% CI for every 50 ug/m3 increase in air pollutants (available from the report by HKU, 1998). The matrix is as follows (Table 4):
Table 4: |
Relative risks (RR) and 95% confidence interval (95% CI) for 50 ug/m3 increase in the concentration of air pollutants for hospital deaths of respiratory and cardiovascular diseases: |
Diseases/Pollutants |
Respiratory |
Circulatory |
Respiratory & Circulatory |
NO2 |
1.14 |
1.10 |
1.12 |
SO2 |
1.08 |
0.89 |
0.93 |
RSP |
1.05 |
1.05 |
1.04 |
O3 |
1.22 |
1.15 |
1.07 |
Source: HKU (Jan., 1998)
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5.3.2 |
Since we have estimated the VSL, the value can be substituted into the model below to value the economic cost of mortality.
E' = [ b'dj) * ( RR' (pi, dj) -1 ) * VSL(dj) ]
where,
E' |
= |
economic cost related to mortality |
b' |
= |
mortality rate due to a particular illness dj |
RR' |
= |
Relative Risk for mortality due to (pi, dj) |
pi |
= |
air pollutants (e.g. NO2, SO2, RSP, and O3) |
dj |
= |
illness (e.g. respiratory or circulatory diseases), |
VSL |
= |
estimated value of statistical life of one additional mortality due to dj |
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5.3.3 |
We shall input the VSL calculated (both the human capital and WTP estimates) to the model to calculate the economic cost of mortality for these two approaches. |
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5.3.4 |
Details of economic cost calculated using human capital estimates are shown in Appendix 9a and Appendix 9b (i.e., as separate-individual diseases and combined - respiratory and cardiovascular diseases) per 50 ug/m3 increase in the pollutants. |
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5.3.5 |
Economic cost of mortality calculated using WTP estimates is shown in Appendix 10a and Appendix 10b (same format as Appendix 9a and 9b). |
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5.3.6 |
The following presents a summary of the economic costs estimated with the relative risks per 50 ug/m3 increase in the air pollutants. Details of the calculations have already been presented as follows:
Appendix 4 and Appendix 5 - COI estimates and economic valuation for morbidity and calculations specifically on the Direct Cost component; Appendix 6 and Appendix 7 - WTP estimates and economic valuation for morbidity; Appendices 8, 9 and 10 - VSL using COI & WTP estimates and the economic valuation of mortality
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5.3.7 |
The following is a summary of the economic cost of health impacts (see Table 5 and Table 6):
Morbidity:
Table 5: |
Results of Economic Valuation Using COI and WTP Approaches: |
Relative Risk
50 ug/m3 |
COI/WTP /D.C.* |
Respiratory Diseases
(HK$ million)
|
Cardiovascular
Diseases
(HK$ million) |
Combined of Respiratory and circulatory Diseases
(HK$ million) |
NO2 |
COI |
522.20 |
451.90 |
852.34 |
D.C. |
269.21 |
239.57 |
445.18 |
WTP |
626.97 |
1,044.42 |
1,462.46 |
SO2 |
COI |
195.82 |
282.44 |
487.05 |
D.C. |
100.95 |
149.73 |
254.39 |
WTP |
235.11 |
652.76 |
835.69 |
RSP |
COI |
326.37 |
169.46 |
487.05 |
D.C. |
168.26 |
89.84 |
254.39 |
WTP |
391.85 |
391.66 |
835.69 |
O3 |
COI |
652.75 |
395.41 |
852.34 |
D.C. |
336.51 |
209.62 |
445.18 |
WTP |
783.71 |
913.87 |
1,462.46 |
Note: * D.C. = Direct Cost
Mortality:
Table 6: |
Results of Economic Valuation Using COI and WTP Approaches: |
Relative Risk
50 ug/m3 |
VSL
(COI/WTP) |
Respiratory Diseases
(HK$ million)
|
Cardiovascular
Diseases
(HK$ million) |
Combined of Respiratory and circulatory Diseases
(HK$ million) |
NO2 |
COI |
1301.93 |
1,397.56 |
2,793.02 |
WTP |
1805.84 |
1,868.12 |
3,789.61 |
SO2 |
COI |
743.96 |
- |
- |
WTP |
1031.91 |
- |
- |
RSP |
COI |
464.98 |
698.78 |
931.01 |
WTP |
644.94 |
934.06 |
1,263.20 |
O3 |
COI |
2,045.89 |
2,096.34 |
1,629.26 |
WTP |
2,837.75 |
2,802.19 |
2,210.60 |
Note: |
There is probably an inconsistent relationship between cardiovascular diseases/ combined respiratory and cardiovascular diseases and the pollutant SO2, thus the RR is less than one. Under such circumstances, it would not be appropriate to estimate the economic cost. |
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5.3.8 |
Details indicating the economic cost per ug/m3 increase in the pollution level is shown in Appendix 11. The results can be used to quantify the economic benefit of the reduction in air pollution. |
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