What is the difference between ground-level concentration and effective emission height?

What is the difference between ground-level concentration and effective emission height?

• A. Ground-level concentration is measured at z = 0; effective emission height accounts for plume rise and source height to determine where dilution begins.
• B. Ground-level concentration is measured at z = 100 m.
• C. Ground-level concentration is the same as effective emission height.
• D. Emission height does not affect dilution start.

Answer: (A)

Ground-level concentration refers to how much pollutant is present at the receptor height right at the ground (z = 0). The effective emission height is the height from which the plume effectively begins to dilute in the atmosphere, taking into account the source height and any plume rise due to buoyancy and momentum. Because plumes from tall stacks rise as they travel, the dilution starts higher up, not at the ground, which changes how much pollutant is left to reach the surface. So ground-level concentration is about the concentration at z = 0, while effective emission height is about the starting height for dilution in the plume, influenced by plume rise and the actual source height. This distinction is why the correct description mentions both the ground-level measurement and the plume-rise-adjusted starting height for dilution.

Ground-level concentration refers to how much pollutant is present at the receptor height right at the ground (z = 0). The effective emission height is the height from which the plume effectively begins to dilute in the atmosphere, taking into account the source height and any plume rise due to buoyancy and momentum. Because plumes from tall stacks rise as they travel, the dilution starts higher up, not at the ground, which changes how much pollutant is left to reach the surface. So ground-level concentration is about the concentration at z = 0, while effective emission height is about the starting height for dilution in the plume, influenced by plume rise and the actual source height. This distinction is why the correct description mentions both the ground-level measurement and the plume-rise-adjusted starting height for dilution.