When predicting air pollutant concentrations, which meteorological parameter is most crucial for accurately determining the ground-level impact?

Wind speed and direction are the most crucial meteorological parameters for accurately determining the ground-level impact when predicting air pollutant concentrations. These parameters directly influence the dispersion and transport of pollutants from their source. Wind speed determines how quickly pollutants are diluted and carried away, while wind direction dictates the path of the plume and the areas that will be affected. Stable atmospheric conditions, characterized by low wind speeds and limited vertical mixing, can lead to higher ground-level concentrations because pollutants are not effectively dispersed. Conversely, high wind speeds and unstable conditions promote greater mixing and lower concentrations. Knowing the prevailing wind patterns and the frequency of different wind conditions is essential for accurately modeling air quality impacts and assessing the potential exposure of nearby receptors to air pollutants. For instance, if a factory emits pollutants and the prevailing wind direction is towards a residential area, the impact on that community will be significantly higher than if the wind typically blows in another direction.