The figure is an example of a graph showing the distribution of nitrogen dioxide (NO2) results at different monitoring sites in the Auckland region using a box plot. The graph shows the distribution of results using percentiles. Each monitoring site box plot provides the following information:
- peak value
- minimum value
- percentile values (99th, 95th, 75th, 25th, 5th and 1st).
This example shows the maximum NO2 result exceeding the 24-hour ambient air quality guideline value of 100 mg/m3 at the roadside site. All results from the industrial, urban and rural sites were within the guideline.
Figure 9.2: Example of figure showing the proportion of PM10 samples belonging to different air quality categories
The figure is an example of a summary statistics graph showing the proportion of PM10 samples belonging to different air quality categories. It presents seven years (2001 to 2007) of data in one graph. Samples are grouped into categories in each of these years. The air quality categories used are:
- Action (>100 per cent of the standard)
- Alert (66-100 per cent of the standard)
- Acceptable (33-66 per cent of the standard)
- Good (10-33 per cent of the standard)
- Excellent (<10 per cent of the standard)
The example shows that the proportion of results collectively belonging to the “Excellent” to “Acceptable” categories ranged from approximately 65 to 90 per cent. In 2004, there were no results in the "Excellent" category. The proportion of results belonging to the "Alert" category was lowest during 2006.