Crankcase emissions belong to which emissions category?

• A. Particulates
• B. NOx
• C. Hydrocarbons
• D. Carbon dioxide

Answer: (A)

Crankcase emissions come from the engine’s crankcase ventilation, carrying oil mist and aerosolized byproducts out into the atmosphere. This form of release is particulate matter—the tiny droplets and solids that travel with the air—rather than a purely gaseous pollutant. While some hydrocarbons may be present, the defining portion of crankcase emissions is the oil mist and related particulates, which is why they’re classified under particulates. The other categories—NOx, carbon dioxide, and hydrocarbons as a broad gaseous group—don’t capture the distinctive particulate nature of crankcase vented emissions.