Why are my NO₂ measurements missing a calibration?

How to identify missing calibrated measurements

Uncalibrated air quality measurements are shown on the Clarity Dashboard as an empty blue circle. We generally do not recommend using uncalibrated data for public data sharing or analysis (except in certain research-oriented applications where raw data are valuable). To see your device’s data without missing calibration measurements, utilize the Data Cleanup toggle above the plot or map.

About the NO₂ global model

The NO₂ global model was developed from hundreds of Clarity Node-S sensor collocations worldwide, yielding a dataset of over six million hourly measurements. To read more about the global NO₂ model, read our blog Introducing Clarity’s Global NO₂ Calibration.

While this model performs well in many scenarios, it may be less accurate in extreme conditions or in locations with pollution sources that are not well represented in the training data. When environmental conditions fall outside a representative range in the training dataset, the model does not produce a calibrated NO₂ measurement to avoid extrapolating beyond the conditions for which it was developed.

For projects requiring higher accuracy or tuned to location-specific environmental conditions, we continue to recommend a local collocation and to work with your Clarity Environmental Project Manager to develop a custom calibration model whenever feasible.

Recommended operating range based on training data

How to check your device calibrations

To confirm which calibrations are assigned to your Clarity Node-S network, visit the article - Check a device's calibration status.