# Air Quality The **PMSA003I** is a high-precision laser-based particulate matter (PM) sensor designed for real-time air quality monitoring in the 3D-PAWS system. This sensor continuously measures and reports the concentration and number of airborne particles of various sizes, providing detailed insight into local air pollution. ### How the Sensor Works * **Laser Scattering Principle:** The PMSA003I uses a laser and a fan to draw air into its detection chamber. As particles pass through the laser beam, scattered light is detected and analyzed to determine particle size and count. * **Particle Output:** The sensor outputs both the **number and mass concentration** of particles in several size bins (e.g., PM1.0, PM2.5, PM10); however, estimates of PM1.0 and PM10 are considered to be less reliable. We only recommend using the sensor for PM2.5 measurements. * **Number concentration** is reported as particles per 0.1 L of air. * **Mass concentration** is reported in micrograms per cubic meter (μg/m³). * **Adaptive Sampling Modes:** * **Stable Mode:** When air quality is steady, the sensor samples at a real interval of 2.3 seconds. * **Fast Mode:** If particle concentrations change rapidly, the sensor automatically switches to fast mode, sampling every 200–800 ms. The higher the concentration, the faster the sampling. * **3D-PAWS Integration:** The 3D-PAWS system samples the PMSA003I every second, recording the average 1-minute value observed during each measurement interval for robust air quality tracking. ### **Power Considerations & Recommendation** > **Note:**\ > The PMSA003I is a **power-hungry sensor** because it runs a fan continuously to ensure accurate, real-time sampling. This significantly increases the station’s energy requirements. > > **For reliable operation, we strongly recommend using a Voltaic V75 battery and a 10 W, 6 V solar panel** for air quality stations equipped with this sensor. ### Instruction Slides for Assembling the Air Quality Sensor {% embed url="" %}