Simple nitrogen dioxide (NO2) chart card

Who it’s for

Environmental health officers, traffic managers, and smart city operators ask “how has NO₂ concentration at this station trended over the last few hours or days?” They want a compact trend chart that fits into a multi-station overview without the overhead of a full chart card.

What it does

A monitoring station streams nitrogen telemetry and the widget renders a time-series chart of those readings, color-coded by severity: 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 fills the card without a large numerical readout, maximizing the visible time window.

• Trend chart of NO₂ concentration over the selected dashboard time window
• Color-coded by severity at each point in time across five bands
• Shows one sensor’s data per widget; add multiple widgets to compare trends across stations

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

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 change the chart colors — edit the color of each range on the Latest data key.

Tips

• Use this chart in a grid alongside simple chart cards for CO, O₃, and SO₂ to give operators a side-by-side multi-pollutant trend view without cluttering the dashboard with large value cards.
• A 24-hour time window makes the typical morning and evening NO₂ traffic peaks visible as recurring patterns, so genuine exceedance events stand out clearly.
• A sustained upward trend over several days at a roadside station can indicate increased heavy vehicle traffic or a change in local wind patterns bringing industrial emissions closer.