About EPA air quality bulletins

EPA measures a range of pollutants at each of its monitoring stations. Each pollutant has a different impact on human beings or the environment. The State Environment Protection Policy (The Air Environment) (SEPP) sets standards for these pollutants.

A National Environment Protection Measure (NEPM) for air has also been developed. This sets nationally agreed air quality standards for a range of pollutants. There is one exception: visibility – where the current SEPP standard will continue to apply.

Bulletin issue

Currently EPA 24-hour summary air quality bulletins are issued twice daily (approximately 9.45am and 3.45pm) from Monday to Friday and daily (3.45pm) on weekends. Hourly data is available 24 hours a day, seven days a week on this website.

Air quality categories

Data in EPA air quality bulletins are expressed in terms of an air quality index. EPA has also adopted five-colour coded air quality categories. Data is assigned to a category based on the index value as listed in the table below.

 

Category	Index range
Very good air quality	0–33
Good air quality	34–66
Fair air quality	67–99
Poor air quality	100–149
Very poor air quality	150 or greater
A grey background indicates that the monitoring station is not instrumented for the pollutant or data is temporarily unavailable.

 

Determination of an overall station summary

The station summary provides an overall picture of air quality at each station. It takes into account all the different pollution measurements made at the station, and provides a station air quality index and air quality category:

• VERY GOOD
• GOOD
• FAIR
• POOR
• VERY POOR
• Offline
• Not Available

Sometimes, there is not enough data to provide an overall summary. For example, some stations have been set up to measure only one pollutant, which may not be enough information to prepare a summary. Also, there may be a pollution monitor installed but it may be offline for maintenance work. In these cases, the station summary will say “not available”.

Sometimes the entire station is out of action, for example due to telecommunications or power failure. In this case, the station summary will say “offline”.

The determination of the station summary is done by checking to see if critical pollutants were successfully measured at that station. The critical pollutants are Particles (PM₁₀) and Visibility Reduction. In other words, one of these measurements must be present before a station summary can be formed.

The only exception to this rule is that if any pollutant records a level which is FAIR or worse, then that pollutant can be used to form a summary.

If there is enough information to prepare a summary, the station air quality index is calculated as the highest of the individual pollutant index values, and the category (VERY GOOD to VERY POOR) is then determined from the station index.

Here are some examples of how the summary works:

Examples of station index calculation

• On 10 June, Pt Henry records an ozone index of 40 (that is, GOOD) and a sulfur dioxide index of 50 (GOOD). As no measurements of PM10 or Visbility Reduction are made at Pt. Henry the station summary will say not available.

• On 2 May, Pt Henry records an ozone index of 45 (that is, GOOD) and a sulfur dioxide index of 90 (FAIR). Even though neither of the critical pollutants have been measured, a station index will be calculated as there is a pollutant index in the FAIR range. The station index will b 90 and the summary will say FAIR.

• On 5 July, no readings are available for the Pt Henry station. As a consequence the summary will say offline.

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