Room air quality sensors mount to vertical surfaces such as walls and pillars and monitor the air quality within the room. They are commonly used to optimize demand-controlled ventilation in rooms that require clean air.

Duct air quality sensors are mounted onto or through the wall of an HVAC duct and measure the air quality of the airstream. This provides information on air quality at specific points in the system, allowing users to diagnose air quality issues and regulate the HVAC system for peak efficiency.