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Modelling Exposure from Airborne Hazardous Short-Duration Releases in Urban Environments
Atmosphere ( IF 2.9 ) Pub Date : 2021-01-20 , DOI: 10.3390/atmos12020130
John G. Bartzis , George C. Efthimiou , Spyros Andronopoulos

When considering accidental or/and deliberate releases of airborne hazardous substances the release duration is often short and in most cases not precisely known. The downstream exposure in those cases is stochastic due to ambient turbulence and strongly dependent on the release duration. Depending on the adopted modelling approach, a relatively large number of dispersion simulations may be required to assess exposure and its statistical behaviour. The present study introduces a novel approach aiming to replace the large number of the abovementioned simulation scenarios by only one simulation of a corresponding continuous release scenario and to derive the exposure-related quantities for each finite-duration release scenario by simple relationships. The present analysis was concentrated on dosages and peak concentrations as the primary parameters of concern for human health. The experimental and theoretical analysis supports the hypothesis that the dosage statistics for short releases can be correlated with the corresponding continuous release concentration statistics. The analysis shows also that the peak concentration statistics for short-duration releases in terms of ensemble average and standard deviation are well correlated with the corresponding dosage statistics. However, for more reliable quantification of the associated correlation coefficients further experimental and theoretical research is needed. The probability/cumulative density function for dosage and peak concentration can be approximated by the beta function proposed in an earlier work by the authors for continuous releases.

中文翻译:

对城市环境中机载危险短期排放的暴露进行建模

考虑到空气中有害物质的意外释放或故意释放时,释放持续时间通常很短,并且在大多数情况下无法确切知道。在这些情况下,由于周围的湍流,下游的接触是随机的,并且在很大程度上取决于释放的持续时间。根据所采用的建模方法,可能需要相对大量的色散模拟来评估曝光及其统计行为。本研究引入了一种新颖的方法,旨在通过仅对相应的连续释放方案进行一次模拟来代替大量的上述模拟方案,并通过简单的关系得出每个有限持续时间释放方案的与暴露量有关的量。目前的分析集中在剂量和峰值浓度作为人类健康关注的主要参数。实验和理论分析支持以下假设:短期释放的剂量统计可以与相应的连续释放浓度统计相关。分析还显示,就总体平均值和标准偏差而言,短期释放的峰浓度统计与相应的剂量统计密切相关。然而,为了更可靠地量化相关的相关系数,需要进一步的实验和理论研究。剂量和峰值浓度的概率/累积密度函数可以通过作者在较早的工作中针对连续释放提出的β函数进行近似。
更新日期:2021-01-20
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