Which characteristic is NOT used to classify microorganisms in air filtration?

The classification of microorganisms in air filtration typically relies on specific characteristics such as size, shape, and type, but color is not a standard criterion used for this purpose.

Size is important because it dictates how effectively filtration systems can capture different microorganisms; larger particles can be trapped by coarser filters, while smaller ones require finer filtration methods. Shape also plays a role, as the morphology of microorganisms can influence their behavior in the air and their interactions with filter media. Different types of microorganisms, such as bacteria, viruses, and fungi, have distinct characteristics and implications for air quality and health effects.

Color does not provide relevant or actionable information for the classification of microorganisms in air filtration contexts, making it the characteristic that is not typically used in this classification system.