Click “+ Add Group” to add a new group comparison (e.g., Road Transport, Power Stations, Domestic Combustion).
You can add up to 10 groups to compare at once.
To remove a group, click “− Remove Group” next to it (this appears when two or more groups are selected).

💡 Tip: You can re-order the group boxes by clicking and dragging the ⠿ handle next to each group — the chart updates automatically.

3️⃣ Set the Year Range

Use the Start Year and End Year dropdowns to focus on a particular time period.
The chart will automatically refresh to show data for the chosen range.

4️⃣ View and Interact with the Chart

Once you’ve chosen your pollutant, groups, and years, the interactive line chart will appear.
Hover over any point on the chart to see the exact emission value for that year.
The Y-axis shows total emissions, including units (e.g., kilotonnes).
Each group is shown in a unique colour.

5️⃣ Use the Legend to Toggle Lines

Above the chart, the legend lists all groups and their corresponding colours.
Click a group name in the legend to hide or show that group’s line on the chart.
Faded items indicate hidden or unavailable data.
(Groups labelled “(No data available)” are included for reference but contain no plotted values.)

6️⃣ Smooth or Straight Lines

Click the “🚫 Disable Smoothing” button to switch to straight (non-curved) lines.
Click again (the button will change to “✅ Enable Smoothing”) to re-enable smooth, curved lines.

7️⃣ Download Options

You can export both the chart and its underlying data for your own analysis or reporting.

📊 Download Chart as PNG
Click “⬇️ Download Chart as PNG” to save the current chart as an image.
The exported image includes:

• The chart itself
• Custom colour legend
• Pollutant name and emission unit

📄 Download Data
CSV: Click “📄 Download Data – CSV” for a spreadsheet-friendly text file.
Excel: Click “📊 Download Data – Excel” for a formatted Excel workbook.
Each file includes:

• Pollutant name and emission unit in the first line
• Table with groups as rows and years as columns
• Footer row with download timestamp

8️⃣ Share Your Chart

Click the Share button to copy a unique link or chart image.
You can easily share your current view with others, or paste the chart image into emails and documents.
The shared link will open the viewer with your selected pollutant, groups, and year range.

9️⃣ View Group Details

Use the “📘 See Group Info” section below the group selector to view details of how each group is built.
The table shows Source Names and Fuel Types from the NAEI data that have been combined to create each group.
If a group includes all sources or all fuel types, these will be shown as “All Sources” or “All Fuel Types”.

🔟 Licensing and Attribution

© Crown copyright (Defra & DESNZ) and available under the Open Government Licence (OGL).
See links beneath the chart for full details.