A qualitative assessment is an observation of visible emissions, or opacity, from a stationary source. The person responsible for making qualitative opacity assessments must be knowledgeable about the effect on visibility of emissions caused by background contrast, ambient lighting, observer position relative to lighting, wind, and the presence of uncombined water in the plume. A qualitative assessment is a brief description of the visible emissions. The qualitative assessment is not required to be six minutes long, and the observer is not required to be certified.
Records usually required for qualitative assessments include: time and date assessment occurred, whether emissions appeared normal, a description of the emission point from which any unusual emissions emanated, steps taken to correct any abnormal emissions, and the name of the person conducting the assessment, and any other information required by the permit.