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Metrics in measurements


A metric brings together several notions into a reportable quantity

  • What is sensed (e.g. PM 2.5, NO2, Wind)
  • A measurable trait of above (e.g. Mass concentration, Speed, Compass direction)
  • The aggregation applied (e.g. No aggregation, 1-Hour mean, 24-hour mean)
  • The units or pollution index applied (e.g. μg/m³, ppb, US EPA AQI)

Attributes within a metric

Some metrics have ready-to-use values directly from the sensor. No further processing occurs. Examples are temperature, relative humidity and wind. Other metrics have raw data that can benefit from further processing in the cloud. We call these metrics cloud-calibrated. Examples are PM2.5 and NO2.

  • Direct from sensor: raw and value are the same
  • Cloud-calibrated: raw is from sensor, value is cloud-calibrated

This means you can consistently access the same attribute regardless of metric, with value being most appropriate for visualization and analysis. Keep an eye on the status field though (see Status table below). If the response is a JSON format, the attributes are in an object, like this (where the word metric is a name from the dictionary below)

   "metric": {

If the response is tabular, like CSV or Parquet, the attributes are dot-notation column headers like this:

    ..., metric.raw, metric.value, metric.status, ...

Attribute details

Clarity Node - metric is direct from sensor

attribute description
raw The sensed value direct from the device
value Same as raw
status sensor-ready

Clarity Node - metric can be cloud-calibratred

attribute description
raw The sensed value direct from the device
value The calibration result. null if calibration has not occurred
status see table below

status for cloud-calibrated metrics

status description
calibration-missing No calibrated value because a calibration was not assigned to the device durign the last processing
calibration-processing Calibration is in process
calibrated-reprocessing A calibrated value exists and a newer calibration is in process
calibration-error Calibration failed for the data coming from the device
calibrated-ready Calibration has completed

For reference sites

attribute description
raw null
value The value direct from the reference provider
status reference-ready

Output frequency

The fields a measurement contains depend on the output frequency of the measurement. Your request to retrieve measurements includes an outputFrequency. Tables below list all the possible metrics, by output frequency.

Output frequency type of measurement
minute And individual sample, received from a deployed device, containing everything that device sends
hour An hourly aggregation
day A daily aggrgegation, where a new day is defines in UTC time

Metrics dictionary

Metric names

These v2 metric names are unique across individual measurements and hourly/daily aggregations. That was not the case for the older v1 API. If you have older API code, watch out for changed metric names

Individual Measurements



metric description
atmPressureIndividual Atmospheric pressure, Individual sample (atm)
no2ConcIndividual NO2 concentration, Individual sample (ppb)
o3ConcIndividual Ozone, Individual sample (ppb)
pm10ConcMassIndividual PM 10 mass concentration, Individual sample (μg/m³)
pm10ConcNumIndividual PM 10 number concentration, Individual sample (#/cm³)
pm1ConcMassIndividual PM 1 mass concentration, Individual sample (μg/m³)
pm1ConcNumIndividual PM 1 number concentration, Individual sample (#/cm³)
pm2_5ConcMassIndividual PM 2.5 mass concentration, Individual sample (μg/m³)
pm2_5ConcNumIndividual PM 2.5 number concentration, Individual sample (#/cm³)
relHumidAmbientIndividual Relative humidity ambient, Individual sample (%)
relHumidInternalIndividual Relative humidity internal, Individual sample (%)
temperatureAmbientIndividual Temperature ambient, Individual sample (°C)
temperatureInternalIndividual Temperature internal, Individual sample (°C)
windDirectionIndividual Wind direction, Individual sample (°)
windSpeedIndividual Wind speed, Individual sample (m/sec)

Hour Aggregations



metric description
atmPressure1HourMean Atmospheric pressure, 1-hour mean (atm)
no2Conc1HourMean NO2 concentration, 1-hour mean (ppb)
no2Conc1HourMeanUsEpaAqi NO2 concentration, 1-hour mean, UsEpaAqi
no2Conc1HourMeanWaDwerAqi NO2 concentration, 1-hour mean, WaDwerAqi
o3Conc1HourMean Ozone, 1-hour mean (ppb)
o3Conc1HourMeanWaDwerAqi Ozone, 1-hour mean, WaDwerAqi
pm10ConcMass1HourMean PM 10 mass concentration, 1-hour mean (μg/m³)
pm10ConcMass1HourMeanWaDwerAqi PM 10 mass concentration, 1-hour mean, WaDwerAqi
pm10ConcMass24HourRollingMean PM 10 mass concentration, 24-hour rolling mean (μg/m³)
pm10ConcNum1HourMean PM 10 number concentration, 1-hour mean (#/cm³)
pm10ConcNum24HourRollingMean PM 10 number concentration, 24-hour rolling mean (#/cm³)
pm1ConcMass1HourMean PM 1 mass concentration, 1-hour mean (μg/m³)
pm1ConcNum1HourMean PM 1 number concentration, 1-hour mean (#/cm³)
pm2_5ConcMass1HourMean PM 2.5 mass concentration, 1-hour mean (μg/m³)
pm2_5ConcMass1HourMeanWaDwerAqi PM 2.5 mass concentration, 1-hour mean, WaDwerAqi
pm2_5ConcMass24HourRollingMean PM 2.5 mass concentration, 24-hour rolling mean (μg/m³)
pm2_5ConcMassNowcast PM 2.5 mass concentration, Nowcast (μg/m³)
pm2_5ConcMassNowcastUsEpaAqi PM 2.5 mass concentration, Nowcast, UsEpaAqi
pm2_5ConcNum1HourMean PM 2.5 number concentration, 1-hour mean (#/cm³)
pm2_5ConcNum24HourRollingMean PM 2.5 number concentration, 24-hour rolling mean (#/cm³)
relHumidAmbient1HourMean Relative humidity ambient, 1-hour mean (%)
relHumidInternal1HourMean Relative humidity internal, 1-hour mean (%)
temperatureAmbient1HourMean Temperature ambient, 1-hour mean (°C)
temperatureInternal1HourMean Temperature internal, 1-hour mean (°C)
windDirection1HourMean Wind direction, 1-hour mean (°)
windSpeed1HourMean Wind speed, 1-hour mean (m/sec)

Day Aggregations



metric description
atmPressure24HourMean Atmospheric pressure, 24-hour mean (atm)
no2Conc24HourMean NO2 concentration, 24-hour mean (ppb)
o3Conc24HourMean Ozone, 24-hour mean (ppb)
pm10ConcMass24HourMean PM 10 mass concentration, 24-hour mean (μg/m³)
pm10ConcMass24HourMeanUsEpaAqi PM 10 mass concentration, 24-hour mean, UsEpaAqi
pm10ConcNum24HourMean PM 10 number concentration, 24-hour mean (#/cm³)
pm1ConcMass24HourMean PM 1 mass concentration, 24-hour mean (μg/m³)
pm1ConcNum24HourMean PM 1 number concentration, 24-hour mean (#/cm³)
pm2_5ConcMass24HourMean PM 2.5 mass concentration, 24-hour mean (μg/m³)
pm2_5ConcMass24HourMeanUsEpaAqi PM 2.5 mass concentration, 24-hour mean, UsEpaAqi
pm2_5ConcNum24HourMean PM 2.5 number concentration, 24-hour mean (#/cm³)
relHumidAmbient24HourMean Relative humidity ambient, 24-hour mean (%)
relHumidInternal24HourMean Relative humidity internal, 24-hour mean (%)
temperatureAmbient24HourMean Temperature ambient, 24-hour mean (°C)
temperatureInternal24HourMean Temperature internal, 24-hour mean (°C)
windDirection24HourMean Wind direction, 24-hour mean (°)
windSpeed24HourMean Wind speed, 24-hour mean (m/sec)