Smoke point is an important product quality specification for jet fuel and other grades of kerosene. Specifically, it is a measure of a fuel's tendency to generate smoke when burned. This is caused by the formation of carbonaceous particles that do not completely combust. These are a concern both because of their effect on the environment and on the engine.
The measure for smoke point is set by the flame height at which smoke begins to form when a fuel is burned in a standardized test burner. Higher smoke point material is more desirable.
The primary driver of low smoke point is the presence of aromatics or naphthalenes.