Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for monitoring air quality with multiple sensing devices. The methods, systems, and apparatus include actions of: obtaining first sensor data from a sensor that is not an air quality sensor, determining that the first sensor data satisfy a first air quality criterion, in response to determining that the first sensor data satisfy the first air quality criterion, obtaining second sensor data from an air quality sensor, determining that the second sensor data satisfy a second air quality criterion, and based on a determination that the second sensor data satisfy the second air quality criterion, activating an air quality device.