Determination of inadequacies/pitfalls in quantifying Air Pollution impacts – A Fault Tree Analysis (FTA) approach

This work deals with the determination of inadequacies/pitfalls in quantifying air pollution impacts. Firstly, the critical pollutant concentration Pcr is determined as the equilibrium point in the tradeoff between indirect environmental (due to impact at societal level) and direct economic (for pollutant abatement) cost. It is proved that certain exogenous factors may intervene in estimating the indirect environmental cost causing uncertainty in the process of pollution impact quantification. For overcoming this difficulty, we have developed initially a methodological framework under the form of an algorithmic procedure and subsequently a fuzzy fault tree for revealing inadequacies/pitfalls and investigating the respective possible causes. Numerical examples referring to the network of air quality monitoring stations (AQMSs) in Athens, Greece, are presented and the results are discussed. Finally, the optimal metrological validity index (incorporating precision and accuracy) of each AQMS is estimated for maximizing total environmental/economic benefit and minimizing uncertainty. Key-Words: air pollution impacts, environmental cost, fault tree analysis (FTA), tradeoff equilibrium, uncertainty, optimization. WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT Fragiskos Batzias, Yiannis Markoudakis E-ISSN: 2224-3496 251 Volume 12, 2016 Fig. 1a. Dependence of the indirect and the direct/economic partial costs C1 and C2, respectively and shifting of the critical pollution concentration from Pcr to P’cr in case of deep/lasting economic recession crisis. to atmosphere (i.e. the higher the abatement of releases) the higher the cost, again disproportionally due to the validity of the well established in Economics Law of marginal or differential Returns (LDR). Evidently, the critical value Pcr is the equilibrium point of the tradeoff between the partial costs C1 and C2, where the marginal costs MC1 = dC1/dP and MC2 = |dC2/dP| are equal. Although this optimization procedure is right from a conceptual point of view, it may be complicated in practice, because of the intervention of exogenous factors causing change of the partial cost C1 and consequent shifting of the initial Pcr value. E.g., in case of economic crisis, hospital admissions may decrease giving underestimated values for C1 for the same pollutant concentrations, since people prefer treatment while staying at home in order to avoid additional expenses; as a result, the corresponding curve C1 moves downwards to C1’, becoming more flat, since the respective influence is more expressed in the region of higher P-values, as a result, Pcr is shifting to P’cr, where P’cr > Pcr, as shown in Fig. 1a. On the contrary, the C1curve is moving upwards to C1’’, becoming steeper, if the cumulative effect of air pollution on human health is taken into account, leading to overestimation of the Fig. 1b. Dependence of the indirect and the direct/economic partial costs C1 and C2, respectively and shifting of the critical pollution concentration from Pcr to P’’cr when the cumulative effect of air pollution on human health is taken into account. current cost (in order to counterbalance respective underestimation in the previous time periods [1,2]); as a result, the initial Pcr-value is shifting to P’’cr, where P’’cr < Pcr (see Fig. 1b). Since the vectors (P’cr – Pcr) and (P’’cr – Pcr) have opposite direction, the final position of the Pcr, in comparison with its initial value, depends on the form of the partial cost functions and their estimated parameter values.