IAQ Interface Module in Fire Alarm Systems Explained

IAQ Interface Module is a generic term for an addressable input module that brings indoor air quality (IAQ) sensor signals (typically carbon monoxide, particulates, or volatile organic compounds) onto a fire alarm loop so that the panel can use them as additional inputs to its cause-and-effect logic.

An IAQ module is not itself a fire detector. It is a digital interface that occupies a loop address and accepts external signals from third-party air quality sensors, presenting their states to the panel as input events. Typical use cases include early warning in spaces where the dominant pre-fire signature is gas-phase rather than visible smoke (for example battery rooms, lithium-ion storage, electrical switch rooms), and integration of indoor air quality with HVAC shutdown logic during a fire.

Naming varies between manufacturers. The same physical product is sold as an IAQ interface, an analogue input module, a CO interface, or a multi-criteria input depending on the brand. What matters at design stage is what range of signals it accepts (volt-free contacts, current loops, RS-485, voltage), how it presents alarms to the panel, and whether the IAQ inputs are listed for life-safety use or only for environmental monitoring. Mixing the two is a common audit finding.

For the loop architecture that hosts the module, see addressable fire alarm systems. For how the panel uses the inputs, see fire alarm cause and effect.