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Metrics selection

A metrics selector is a useful notation for controlling which metrics are returned in the measurement. When you request measurements -- either recent or historical -- you can limit which metrics get returned with the metricSelect parameter. Here are some examples, following by a more complete description of the notation:


Desired metrics metricSelect value
The metrics that are returned by the API by default absent or default
Every metric all
Only metrics that start with “no2”
(or similarly, only the category of NO2 pollutants)
only no2*
only :no2
Only metrics that are in the category of pollutants
(thus leaving out environmentals like temperature and humidity)
only :pollutant
Only what a Node2 reports (no accessory module metrics) only :node2
Defaults but not AQIs default - *aqi*
Only Nowcasts only *nowcast*

Metrics select language

The metrics selector creates a set, progressing left-to-right. The language is case-insensitive.


A selection starts with

  • default or absent - set of default metrics
  • all - all the metrics for the given output frequency
  • none or only - the empty set
Add and remove

Then the language adds to or removes from the set. If not specified, you are adding. The selector only xxx starts with the empty set and then adds xxx.

Plus + and minus - toggle between add-to-set and remove-from-set. The selector none + no2* - *aqi starts empty, adds metrics that begin with "no2" and then remove metrics ending with "aqi".

Star matching

An asterisk * matches any text sequence.

  • * matches any text (so, all metrics)
  • temperature* matchings all text that starts with "temperature"
  • *rolling* matching any text with the word "rolling" in it. This would select all the rolling means.
Category matching

There are predefined categories of metrics that can be indicated with a leading colon :
For example, only :blackcarbon selects only the black carbon netrics



  • :pollutant - the PMs, NO2, ozone, black carbon
  • :met - meteorological: ambient temperature & RH, wind, atmosperic pressure
  • :internal - internal temperature & RH
  • :particulate - the PMs, black carbon
  • :gas - ozone, NO2

Specific pollutants

  • :pm1   :pm25   :pm10
  • :no2
  • :ozone
  • :blackcarbon


  • :temperature
  • :rh
  • :wind

Only sensed by the Node2 itself (does not include accessory modules)

  • :node2