Parameter and model uncertainty in a life-table model for fine particles (PM2.5): a statistical modeling study.
BACKGROUND
The estimation of health impacts involves often uncertain input variables and assumptions which have to be incorporated into the model structure. These uncertainties may have significant effects on the results obtained with model, and, thus, on decision making. Fine particles (PM2.5) are believed to cause major health impacts, and, consequently, uncertainties in their health impact assessment have clear relevance to policy-making. We studied the effects of various uncertain input variables by building a life-table model for fine particles.


METHODS
Life-expectancy of the Helsinki metropolitan area population and the change in life-expectancy due to fine particle exposures were predicted using a life-table model. A number of parameter and model uncertainties were estimated. Sensitivity analysis for input variables was performed by calculating rank-order correlations between input and output variables. The studied model uncertainties were (i) plausibility of mortality outcomes and (ii) lag, and parameter uncertainties (iii) exposure-response coefficients for different mortality outcomes, and (iv) exposure estimates for different age groups. The monetary value of the years-of-life-lost and the relative importance of the uncertainties related to monetary valuation were predicted to compare the relative importance of the monetary valuation on the health effect uncertainties.


RESULTS
The magnitude of the health effects costs depended mostly on discount rate, exposure-response coefficient, and plausibility of the cardiopulmonary mortality. Other mortality outcomes (lung cancer, other non-accidental and infant mortality) and lag had only minor impact on the output. The results highlight the importance of the uncertainties associated with cardiopulmonary mortality in the fine particle impact assessment when compared with other uncertainties.


CONCLUSIONS
When estimating life-expectancy, the estimates used for cardiopulmonary exposure-response coefficient, discount rate, and plausibility require careful assessment, while complicated lag estimates can be omitted without this having any major effect on the results.
Tainio
Marko
M
Centre of Excellence for Environmental Health Risk Analysis, National Public Health Institute, Kuopio, Finland. Marko.Tainio@ktl.fi
Tuomisto
Jouni T
JT
Hänninen
Otto
O
Ruuskanen
Juhani
J
Jantunen
Matti J
MJ
Pekkanen
Juha
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000209:etiology / Q000401:mortality*; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D005387:Finland / Q000453:epidemiology; D005102:Health Expenditures; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008017:Life Expectancy / Q000639:trends*; D015993:Life Tables; D008175:Lung Neoplasms / Q000209:etiology / Q000401:mortality*; D008875:Middle Aged; D009010:Monte Carlo Method; D009026:Mortality / Q000639:trends; D052638:Particulate Matter / Q000009:adverse effects* / Q000191:economics; D012680:Sensitivity and Specificity; D035501:Uncertainty; D014504:Urban Health / Q000706:statistics & numerical data*; D001335:Vehicle Emissions / Q000032:analysis / Q000633:toxicity
D052638:Particulate Matter; D001335:Vehicle Emissions
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