types of substances emitted, environmental conditions, proximity to other sources of contaminants, and frequency of process upsets. The people who might be exposed to the contaminants are likely to differ in their susceptibilities and activity patterns. Some uncertainties are specific to waste incineration, and some are inherent in any activity that releases contaminants into the environment.
Some of the uncertainties and variability can be reduced or better accounted for; others will remain intractable. The most-effective decisions concerning the siting, design, operation, and regulation of incineration facilities are the ones that take uncertainty and variability fully into account.
Incinerator risk assessments should include the following components of uncertainty and variability analyses
An estimate of the variability and uncertainty distributions of all input values and their effects on final estimates.
A sensitivity analysis to assess how model predictions are related to variations in input data.
Variance-propagation models that show how the variability and uncertainty of final results are tied to the uncertainties and variabilities associated with the various models, their inputs, and assumptions used throughout the risk assessment.
The committee's evaluation of waste incineration and public health was substantially impaired by the lack of available compilations of the ambient concentrations of pollutants resulting from incinerator emissions. In addition, large variabilities and uncertainties associated with risk-assessment predictions often limit the ability to define risks posed by incinerators.