1.9 in 1: Multifunctional air detector that measures CO2 concentration, CO concentration, TVOC value, HCHO value, PM2.5/PM10 value, temperature and relative humidity. Why you need it: monitors key indoor air quality metrics in a single device to support safe ventilation, occupant comfort and environmental monitoring in daily spaces. Suitable applications: office, school, warehouse, and agricultural plantings. It has no startup calibration required and operates automatically. Sensor technology and performance: uses an air semiconductor PM2.5 sensor and an electrochemical performance chip for accurate readings. The readings are precise, with accuracy up to 1 PPM. Display and alerts: large digital screen with backlight for clear reading; includes an alarm function to alert when values exceed set thresholds. Use scenarios: In an office or classroom to track CO2, CO, TVOC, HCHO, PM levels and adjust ventilation to maintain air quality. In warehouses or greenhouses to monitor PM2.5/PM10, VOCs and humidity/temperature, helping protect stored goods and crops. In shared workspaces or laboratories where automatic monitoring and alarm notifications support a safer environment without manual calibration.