A dryer exhaust duct alarm detects the presence of lint or other obstructions in an exhaust duct or vent. A thin lever is suspended within the duct and is slightly cupped in shape to more effectively capture air flow. In the presence of uninhibited air flow, the lever is substantially displaced from its initial substantially-vertical position toward a substantially horizontal position. But when airflow is inhibited, the lever is not sufficiently displaced. A detector detects operation of the dryer. If the dryer operates for a determined period of time but the lever is not sufficiently displaced, the user is alerted of the problem. Other data may also be presented to the user, including real-time data over a communication medium.