Effect Of Temperature And Humidity On Low-Cost Air Quality Sensor Readings

Low-cost air quality sensors are increasingly used in environmental monitoring networks, but their readings change when temperature and humidity change, even if the actual pollution level stays the same. This paper investigates how much temperature and relative humidity affect the readings of three common sensor types — an optical particle counter for PM2.5, a metal-oxide gas sensor for NO₂, and an electrochemical sensor for CO₂. Sensors were placed in a controlled chamber and exposed to six combinations of temperature (15–35 °C) and relative humidity (30–90%). Results show that measurement error grows significantly at high humidity levels, with PM2.5 error reaching nearly 9 µg/m³ at 85% relative humidity compared to 1.2 µg/m³ at 30%. A simple linear correction formula is proposed that reduces this error by up to 74%. The findings confirm that environmental compensation is necessary for reliable low-cost sensor deployments.

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