Automatic actuation of device according to UV intensity

A device automatically actuated according to UV intensity includes a UV detector generating an electric signal indicative of a UV intensity of a light received thereby; a comparator in communication with the UV detector, receiving the electric signal to compare the UV intensity with a first threshold value, and asserting an actuating signal when the UV intensity is in a predetermined correlation with the first threshold value; and an actuated object in communication with the comparator, actuated to change a state thereof in response to the actuating signal. The actuated object can be an anti-glare rearview mirror, a sunshade curtain, a headlamp, or a transmittance-adjustable window of a vehicle. The actuated object can be a sunshade curtain or a transmittance-adjustable window of a building.