Nitrogen dioxide (NO2) chart card

Who it’s for

Environmental health officers, traffic managers, and smart city operators ask “what is the NO₂ level at this station right now, and has it been rising or falling over the last few hours?” They need both the current reading and the recent trend on a single card to distinguish a genuine escalation from normal rush-hour fluctuation.

What it does

A monitoring station reporting nitrogen = 28 µg/m³ shows the current value color-coded by severity alongside a time-series chart of recent readings: green for Good (0–40 µg/m³), light green for Moderate (40–90 µg/m³), orange for Elevated (90–120 µg/m³), dark orange for High (120–230 µg/m³), and red for Hazardous (above 230 µg/m³). The chart lets operators see whether an elevated reading is a new spike or a persisting problem.

• Live NO₂ reading in µg/m³ with color coding across five severity bands
• Historical trend chart shows how NO₂ concentration has evolved over the selected time window
• Shows one sensor’s data per widget; add multiple widgets to track and compare stations across a network

How to set up

Data keys

Key	Role	Type	Description
nitrogen	Chart series	Timeseries	Nitrogen dioxide concentration in µg/m³; change the key name to match your device’s telemetry key
Latest	Latest value	Timeseries	The headline figure above the chart. Its own color ranges are where the band colors are edited
Delta percent	Percentage change	Timeseries	Change against the previous period, as a percentage
Delta absolute	Absolute change	Timeseries	Change against the previous period, in the key’s own unit

The widget ships with a simulated function datasource key labeled Nitrogen dioxide, so it draws random values until you point the datasource at a device and rename the key.

To point it at your own device: open the dashboard in edit mode, open the widget’s Datasources, pick the entity or entity alias, and replace the function key with the key your device reports.

Value ranges

Range	Level	Color
0–40	Good	Green
40–90	Moderate	Light Green
90–120	Elevated	Orange
120–230	High	Dark Orange
230+	Hazardous	Red

How to customize

• To change the time window — adjust the dashboard time filter to show the last hour, day, or week of NO₂ readings.
• To change the severity thresholds — edit the color ranges on the Latest data key to match your local regulatory limits.
• To change the band colors — edit the color for each severity level in the widget settings.

Tips

• NO₂ peaks sharply during rush-hour traffic; a 24-hour chart makes morning and evening peaks immediately visible, helping operators distinguish normal patterns from genuine exceedance events.
• Compare readings at multiple stations simultaneously to determine whether elevated NO₂ is localized to one roadside sensor or part of a wider urban air quality episode.
• For compliance reporting, use the chart’s export feature to download the raw time-series data for the period under review.