ORIGINAL PAPER Use of computer dynamic simulation for indoor exposure assessment based on chronogram incident as air pollution source characterization Jordi Bonet • Valentin Plesu • Alexandra Elena Bonet Ruiz • Petrica Iancu • Jose Costa Received: 9 July 2013 / Accepted: 3 October 2013 / Published online: 12 October 2013 Ó Springer-Verlag Berlin Heidelberg 2013 Abstract Determination of the level of exposure due to a chemical incident is crucial for the assessment of public health risks and environmental impact. This kind of information is also useful for the subsequent legal responsibilities. If the air contaminant concentrations are not quantified during the incident, then its air concentration may fall below detectable levels shortly after the incident has passed. In case of smelly compounds, usually the incident chronogram indicates the time when the smell was detected and when the smell was gone. Unfortunately, an objective and analytical measure of odour is impossible. The present study shows that it is possible to computer simulate the concentration evolution in time for a defined indoor scenario. Comparing the odour detection in the chronogram with the computer simulations, it is feasible to determine the maximum gas contaminant exposure during the incident and its evolution in time. Once the pollution source indoor concentration is characterized, considering the overall air renewal time and a plume model, the effects on the environment around the building can be estimated. Keywords Simulation Á Air contaminant concentration Á Dynamic simulation Á Aspen Plus Dynamics Á Maximum exposure assessment Introduction When there is an accidental gas emission, the immediate effect is on the nearby area where it took place. In case of an indoor incident accompanied by air contamination with a chemical volatile substance, detected by its pungent odour, it is required to determine if the exposure levels in the air could have produced some adverse effect to the employees. Odour perception is a primal sense that can subconsciously warn of danger. The human nose is able to detect low concentrations of many organic compounds; also some simple compounds not containing carbon, such as hydrogen sulphide and ammonia, are detected. Unfor- tunately, an objective and analytical measure of odour is impossible. The human nose is not able to quantify the concentrations and the subsequent danger, but it is ready to detect the presence of a large number of contaminants. Determination of the concentration level is crucial for the assessment of public health risks, environmental impact and appropriate remedies, as well as for subsequent health and environmental impact studies (WHO 2009). Studies that include concentration level assessment might con- tribute to effective disaster management (Bongers et al. 2008). A computer dynamic simulation programme, typi- cally used to study the dynamic behaviour of chemical processes (Gangadwala et al. 2008), can be useful to vir- tually reproduce the incident. Before the construction of a chemical plant, its dynamic behaviour is checked by means of simulation software (Aspen Plus Dynamics Ò 2013). The programme includes a wide database of chemical compounds properties and thermodynamic models to calculate the physico-chemical properties of the flow streams. The software solves com- plex systems of differential equations to find the evolution of the chemical process due to a certain perturbation and J. Bonet Á A. E. Bonet Ruiz (&) Á P. Iancu Á J. Costa Department of Chemical Engineering, Faculty of Chemistry, University of Barcelona, 1, Martı ´ i Franque `s Street, 08028 Barcelona, Spain e-mail: a_bonet@chim.upb.ro V. Plesu Á A. E. Bonet Ruiz Centre for Technology Transfer in Process Industries (CTTPI), University POLITEHNICA of Bucharest, 1, Gh. Polizu Street, 011061 Bucharest, Romania 123 Clean Techn Environ Policy (2014) 16:971–977 DOI 10.1007/s10098-013-0679-2