The UEi AQM4 Indoor Air Quality Meter meter measures CO2 levels, CO levels, air temperature, dew point, wet bulb temperature, and humidity. The AQM4 is an ideal instrument for indoor air quality (IAQ) diagnosis. The portable UEi AQM4 Indoor Air Quality Meter uses NDIR (non-dispersive infrared) technology for CO2 measurement to ensure reliability and long-term stability. It is useful in verifying HVAC systems performance and air ventilation control.

Poor indoor air quality causes tiredness, inability to concentrate, and even illness (ex. Sick Building Syndrome). IAQ monitoring and surveying especially for CO2 levels and air ventilation has become widely applied in public offices, classrooms, factories, hospitals, and hotels. It is also recommended for regulating standards of industrial air quality in some countries.