Air quality index
Air quality data tables displaying hourly air quality data are updated online throughout the day.
The air quality index is calculated by converting the measured pollutant concentrations into index values. To generate these values, pollutant concentrations are expressed as a proportion of the Air NEPM standards or EPP (Air) goals, and then categorised according to that value.
Hourly air quality indices are available for South East Queensland, and the Gladstone, Mackay, Townsville, and Mount Isa regions. These values make it easier to interpret current air quality data because they overcome the complexity associated with displaying pollutant concentrations.
The five categories in the department's Air Quality Index, ranging from very poor to very good are defined by index value ranges and colours as shown.
Not Available |
Very Good 0-33 |
Good 34-66 |
Fair 67-99 |
Poor 100-149 |
Very Poor >150 |
How the index is calculated
The concentration of a pollutant is measured by air quality monitoring equipment at a monitoring station. This is then converted to an index value using the equation below.
Index value = pollutant concentration x 100 pollutant goal concentration
The pollutant goal concentration used to calculate the index value is the Air NEPM standard for that particular pollutant (or the EPP(Air) goal in the case of visibility).
Once the index value is known, air quality is indicated by the colour and category value.
Index values over 100 indicate that the pollutant concentration exceeds the goal or standard. With the exception of visibility, the goals and standards are based on health studies and standards from around the world. The visibility goal is designed to protect visual amenity (how far you can see).
Pollutants monitored
The department has a network of air quality monitoring stations in Queensland chosen to measure pollutants that are typical of the region and its activities. Pollutants include carbon monoxide, nitrogen dioxide, ozone, particles, sulfur dioxide, and visibility.
Find out how the air quality monitoring data recorded at a departmental monitoring station travels to your computer screen.
Air quality goals used
The Air NEPM standards and the EPP(Air) goal for visibility are presented in the table below. The averaging times for the concentrations of the pollutants are included in the table.
Pollutant |
Air NEPM Standards |
Averaging Time |
0.10 ppm |
1 hour |
|
0.12 ppm |
1 hour |
|
0.20 ppm |
1 hour |
|
9 ppm |
8 hour |
|
50 µg/m3 |
24 hour |
|
25 µg/m3 * |
24 hour |
|
80 µg/m3 ** |
24 hour |
Notes:
* NEPM Advisory Standard
** Good practice guide for assessing and managing the environmental effects of dust emissions
Pollutant |
EPP(Air) Goal |
Averaging Time |
20 km |
1 hour |
The EPP (Air) goal for visibility-reducing particles is 20km visibility, which means you would be able to see clearly for at least 20 km.
This goal is related to a light scattering coefficient value measured using a nephelometer. The degree of scattering is inversely proportional to the visibility. A scattering of 235 Mm-1 or less is equivalent to a visibility of more than 20 km.
The 1 hour, 8 hour and 24 hour averaging times are for the most recent periods (that is the latest 1 hour, 8 hour and 24 hour periods).
ppm: parts per million
µg/m3: micrograms per cubic metre
Mm-1: per million metres
Last updated: 27 October 2009