Methodological features of health risk assessment in acute inhalation effects on the population

Risk assessment of acute inhalation effects on the population has methodological features at all stages of the research. When choosing priority substances, a modification of the method for calculating the relative hazard index by the emission value (in g/sec) is proposed. To assess acute risk, 1-hour averaging of concentrations coinciding in duration with reference levels of acute inhalation effects (ARfC) is used. The use in modeling program of a maximum hourly emission value for each source results in an unreasonable overestimation of the values of 1-hour concentrations. The standard parameters of the emission sources from the report on permissible emissions ( PDV) do not provide the data for the mode of sources (on/off), the actual emission rates (g/sec) for each hour, and other parameters that specify the sources operation. Recommendations were developed for calculation of 1-hour concentrations close to real, in assessing the exposure, structure, and format of the additional data and a computer package for the data connection to AERMOD and ISCST3 models, as well as for the truncation of the time series of calculated 1-hour concentrations at 95-98th percentile. Features of the acute risk indices calculation — coefficients (AHQ) and indices (AHI) are described. Using the hourly values of the time series of concentrations the highest AHQ value is determined at each exposure point, which is used to estimate the level of acute risk from a substance. To calculate the hazard index (AHI) of the substances affecting the same critical organs/systems, the AHQ hourly values of individual substances are summarized at each exposure point, the highest AHI value is determined, which is used to assess the level of acute risk from exposure to substances with unidirectional action. The approbation of the described methodical approaches has shown their effectiveness in determining the values of exposures and risks close to real values. Their use has reduced the values of AHQ and AHI acute risk indices to "plausible" values by 2 and 3.7 times, respectively.