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Characterisation Method Information

Characterisation Method Name:

Respiratory effects impact on DALYs

Version:

2000

Date Completed:

2000

Principal Method Name:

ECO-indicator

Method Description:

DALY (Disability Adjusted Life Years)

Description of the problem

In epidemiological studies it has been shown that several non organic substances and dust are related to respiratory effects in humans. In a recent literature review by [PILKINGTON ET AL1997] epidemiological
data on respiratory effects from environmental pollution are summarised. According to Pilkington the following substances cause respiratory effects:
• Particulate matter PM10 and PM2.5
• Nitrate and sulphate
• SO3
• O3
• CO, and probably
• NOx

The primary emissions that cause exposure to these substances are PM10 , PM2.5 , TSP, NOx , NH3, CO, VOCs, and SOx. These substances are considered as primary pollutants in the fate analysis.

Fate analysis

[HOFSTETTER 1998] calculated fate factors for particles with a simple model using assumptions on residence time and dilution height. These fate factors are compared to literature data. For all primary emissions the results of several statistical methods using empirical and modelled data (a.o. the
European Monitoring and Evaluation Programme and ExternE) are compared. Best estimates have been made for the fate factors based on three main principles:
1. The fate factors should be appropriate for European conditions.
2. Preference is given to fate factors for which the underlying assumptions are known.
3. Average fate factors that assume a proportional relation between emissions and concentration have been used for all but ozone creation. In this case the marginal factor was considered most appropriate in order to reflect the non-linear atmospheric chemistry of ozone formation.

THE UMBRELLA PRINCIPLE FOR INDIVIDUAL VOCS: POCP (Photo Oxidant Creation Potential)
One fate factor has been estimated [HOFSTETTER 1998 ] for total NMVOC (Non Methane Volatile Organic Compounds), but the reactivity of single hydrocarbons varies widely and should be considered when the mixture of VOC emissions is known or
if, e.g., one wants to support the decision on the choice between solvents.
A differentiation between single hydrocarbons can be undertaken by applying the concept of Photochemical Ozone Creation Potential (POCP). The POCP expresses the incremental ozone concentration per incremental emission for a specific VOC specie normalised by the ratio for ethylene.
Ethylene serves as the reference substance and is one of the most reactive VOCs. The unit is without dimension and the POCPs are normally given as a percentage of the one for ethylene. Based on the most recent data on POCP and fate factors for organic substances reported by [JENKIN ET AL 1997] fate factors have been calculated by [HOFSTETTER 1998] for about 120 single VOCs. They are representative for climatic conditions typically found in North-western Europe.

Estimation of dose-response relations
For the damage analysis of emissions that cause respiratory effects the epidemiological approach is used.
Toxicological experiments do not produce effects at ambient concentrations, because test populations used are not representative and the substance is not equal to the substances in the environment. For this
reason and the reason that the slope factor for the dose-response curve is not constant, toxicological data are difficult to extrapolate to effects at ambient concentrations.
On the other hand the epidemiological approach suffers from limited possibilities to prove causalities, to show correlation with several dozens of substances and to attribute health risks among pollutants
with identical emissions sources. On the other hand the epidemiological approach can profit from a large body of literature and has already been used in several externality studies. Therefore this approach will be used to estimate DALYs for respiratory diseases caused by environmental pollutants.
Criteria for causation are used to assess the validity of dose-response relations derived from epidemiological studies. In selecting valid dose-response relations the following criteria apply:
1. The effects come after the exposure.
2. Biological plausibility (depending on the level of knowledge).
3. Consistency of results from large set of studies with similar objectives but different approaches
4. Results should be coherent.
The epidemiological information that is used by [HOFSTETTER 1998] is mostly derived from extensive and detailed reviews by [DONNAN ET AL 1997] and [PILKINGTON ET AL 1997]. The assumptions which are necessary to calculate exposure-effect slopes are taken from [PILKINGTON ET AL 1997].
• Particles: epidemiological evidence on adverse acute health effects of air polluted with particles is very substantial. There is strong but much less widespread epidemiological evidence on chronic
health effects. Sulphates are assumed to result in very small particles (PM2,5), whereas nitrates result in PM10. A conversion factor is used to calculate the relationship for PM2,5.
• Ozone: The overall evidence strongly supports the view that the acute effects of ozone can be quantified and that they should be added to those of particles.
• Sulphur dioxide: Some study results establish a clear association between SO2 and mortality, but causality is not proven yet.
• CO: there is little epidemiological evidence concerning CO. The relationship between CO and acute mortality is used in the calculations.
• Nitrous dioxide: a positive association between NO2 and mortality and respiratory hospital admissions is reported.
In the calculations it is assumed that the slopes are independent from ambient concentrations [PILKINGTON 1997]. The slope at the ambient concentration in the study region is taken as a proxy. However, such a linear relation is questionable when it is applied to vulnerable risk groups. It is the % increase in effect, which is found to be constant at all levels of concentration. In the study of [HOFSTETTER 1998] this simplified assumption is justified because the background concentrations of the study region and of the release assessed in the LCA may be similar and -more important- because the results are dominated by mortality which shows little dependency on the background concentration.
Exposure-response functions are determined using the information on ambient concentrations, population density in the study area, daily hospital admissions for respiratory causes and the relative
risk. The calculated exposure-response slopes have a background similar to the one of the Unit Risk factors for carcinogenicity. However, no generally accepted list of exposure-response
slopes for respiratory diseases has been published yet. The non-terminal endpoints are not yet defined sharply enough to allow for an international compilation [HOFSTETTER 1998]. This means the calculation of damage to human health from respiratory effects can be considered more experimental than the calculations for damage from carcinogenic substances.

Damage analysis

To calculate final results in DALYs the seriousness and duration of the diseases had to be estimated.

The disability weights are estimated using the weights from Murray as a starting point, because no disability weights have been established for all endpoints. Also the duration of illness has been estimated. Literature values sometimes have a large variation. Poor data for life years lost due to premature death caused by respiratory effects had to be used.[HOFSTETTER 1998]

Literature Reference:

1. [Hofstetter 1998] Hofstetter, P. (1998): Perspectives in Life Cycle Impact Assessment; A Structured Approach to Combine Models of the Technosphere, Ecosphere and Valuesphere. , Kluwers Academic Publishers, 1998, Info: www.wkap.nl/book.htm/07923-8377-X. 2. [Pilkington et al 1997] Pilkington A., Hurley F., Donnan P., Health Effects in ExternE Transport: Assessment and Exposure-Response Functions, Institute of Occupational Medicine, Edinburgh, Draft July 1997 3. [Jenkin et al. 1997] Jenkin M.E., Hayman G.D., Derwent R.D., Saunders S.M., Pilling M.J., Tropospheric Chemistry Modelling: Improvements to Current Models and Application to Policy Issues, AEA/RAMP/20150/R001 Issue 1, AEA Culham 1997.

Methodological Range:

perspectiveGeographical range is Europe The data are based on hierarchist perspective

Notes:

Existing Characterisation Factors of Respiratory effects impact on DALYs

Characterisation Parameter

Category Indicator

Impact Indication Principle

Aspect

Substance

Quantity

Unit

Notes

CFactor

DALYs