Abstract: Atmospheric turbulence on a micrometeorological scale can lead to concentration peaks in very short time intervals, on the order of seconds or minutes. Exposure to these peaks can cause discomfort and immediate serious impacts, depending on the emitted pollutant, when the peak exceeds sanitary limits. Short-term individual exposure is especially crucial in cases of release of toxic, flammable, and odorous gases into the air, as they can be dangerous and harmful to health at relatively low concentrations and short exposure times. Additionally, it is even more concerning in urban areas, where the presence of buildings significantly alters the structure of atmospheric turbulent flow. To analyze the impacts of atmospheric emission of toxic substances, flammables, or odor fluctuations on health, it is necessary to calculate the average concentration over a short time interval, on the order of seconds or minutes. As legislation and dispersion models typically use at least hourly average concentration, alternative techniques have been developed to estimate short-term individual exposure. Among them is the Power Law function (peak-to-mean ratio), which relates the average concentration over a longer time interval to the maximum average concentration over a shorter time interval. Another model, developed by Bartzis et al. (2008), derived from the Power Law function, relates the maximum average concentration to parameters such as turbulence intensity and integral time scale of concentration. The objective of this article is to analyze the influence of wind direction, receptor point height, and time interval on predicting the maximum short-term average concentration, using these two models, and on the integral time scale of concentration. For this purpose, wind tunnel data from the works of Castro et al. (2017) and Fuka et al. (2018) were utilized. In these studies, the authors conducted flow and dispersion experiments in an idealized urban model, composed of 14 x 21 = 294 rectangular blocks with a width of 2H, length of H, and height of H, where H = 70mm.

Keywords: Peak-to-mean, Averaging time, Short time interval, Peak concentration, Wind tunnel measurements.