What is the role of receptor height in Gaussian plume predictions?

• A. It has no effect on predicted concentrations.
• B. It determines the point along the vertical axis where concentration is evaluated, influencing the peak concentration location.
• C. It only matters for ground-level receptors.
• D. It only affects wind speed.

Answer: (B)

The key idea is that the vertical distribution of pollutants in a Gaussian plume is described as a Gaussian function of height. Receptor height fixes the vertical coordinate at which you sample that distribution. Since the plume’s concentration changes with height—peaking near the plume centerline and then tapering off toward the ground or higher up—the height at which you place the receptor determines which part of the vertical profile you taste. That choice directly influences both the predicted magnitude of concentration and the vertical position where the peak occurs. So, receptor height sets the evaluation point along the vertical axis and thus where the peak concentration appears.

This isn’t a statement about wind speed, and it isn’t true that height has no effect or that it only matters for ground-level receptors. The height choice matters for any receptor because the vertical distribution governs how much concentration is predicted at that specific height.