Humidity Control for Accurate Particulate Monitoring

Why Humidity Skews PM Readings

High humidity can distort particulate matter (PM) readings by causing airborne particles to absorb moisture and grow, increasing their apparent size and mass, while also risking condensation on sensor optics. This leads to inflated PM values, especially in foggy, rainy, or highly humid environments. Oizom’s heated inlet addresses this problem directly by gently warming the sampled air to keep it above the dew point, ensuring that what gets measured is dust, not moisture.

How the Heated Inlet Works

The heated inlet is a small resistive heating element installed at the sample intake. It is designed to raise the temperature of incoming air just enough to prevent condensation while operating at low power. Integrated into rugged housings made of aluminum or powder-coated steel, the inlet is controlled internally and turns on automatically when needed. It is built with conductive, anti-static materials to prevent particle loss and fits directly into the active airflow path. Operating across a wide environmental range from -20°C to 60°C, the heated inlet is designed for high-humidity and challenging outdoor conditions, helping maintain consistent, reliable monitoring performance across diverse applications. The system maintains a default heating temperature of 45°C to minimize moisture interference and improve data stability.

Precision in Every Sample

By slightly increasing the air temperature, the heated inlet lowers the relative humidity of the sampled air by about 30% (keeping it below the condensation threshold before it reaches the sensor). This “dries” the sample before it reaches the sensor. As a result, the optical particle counter measures only solid dust and particles, not fog or microdroplets. This reduces false PM spikes and improves overall data stability. Your data becomes more accurate and reliable, even in extreme weather conditions.

Built for Real-World Environments

The heated inlet is a standard feature in Oizom’s Pro-level particulate monitors, such as the Dustroid Pro. It is especially effective in high-humidity settings such as tunnels, mines, construction zones, cement plants, and coastal sites. In real-world deployments such as the Skanska tunnel project in Norway, thermal power plants, seaports, and smart-city networks in India, the heated inlet has helped maintain stable monitoring performance during fog, coastal humidity, and monsoon conditions. This ensures that automated actions, such as ventilation or misting, respond only to actual pollution, not to humidity-driven noise.

Low Maintenance, High Performance

The heated inlet operates autonomously and does not require independent calibration; its temperature setting is factory-set and monitored through device firmware. It works seamlessly as part of the sampling system. Regular maintenance involves periodic cleaning of the inlet mesh and air intake, typically once a month or quarter, depending on dust levels. The heater’s function is tracked through device firmware, ensuring it remains operational without manual checks. Standard zero and span calibration for the PM sensor is all that’s needed to maintain system accuracy.

Aligned with Global Standards

Oizom’s approach to humidity control meets international quality expectations. Devices are calibrated in ISO/IEC 17025-accredited (NABL) laboratories and follow EPA performance specifications. Heated inlets support EPA guidance on PM monitoring in humid environments and help maintain relative humidity (RH) below 80%, thereby improving data consistency with reference-grade monitors. Dustroid’s MCERTS certification further confirms its performance under varied environmental conditions.

Reliable Data, No Matter the Weather

With the heated inlet, Oizom ensures your air-quality data remains consistent and actionable. It eliminates misleading PM spikes caused by moisture and maintains sensor accuracy across seasons, geographies, and use cases. Whether you are monitoring a city, a tunnel, or a factory, Oizom’s heated inlet keeps your decisions based on real pollution, not weather artifacts.