The Madison Fire Department evacuated an apartment building after an idling vehicle parked nearby caused a carbon monoxide detector to go off Saturday afternoon. Shortly after 2 p.m. Saturday, MFD crews were dispatched to 21 Sayner Court after someone inside the apartment complex called 911 reporting a carbon monoxide detector that went off. Fire crews noticed a strong odor of vehicle exhaust in the hallway near the front door, prompting them to evacuate residents. Their air monitor detected 40 ppm of carbon monoxide in the first floor hallway and 104 ppm in the underground parking garage. MFD noted that exposure to at least 50 ppm of carbon monoxide for eight or more hours can lead to symptoms including illness and death.