Using our minute data, we report concentrations as hourly and daily averages. All averages are arithmetic means.
Hourly
Data are collected continuously at each monitoring site for the selected parameters and these are reported as hourly data readings in scientific units.
At some rural network sites instruments power up every 15 minutes to sample for one minute, and only continue measurements if total suspended particle (TSP) concentrations exceed 25 µg/m3. In this case, unlike the standard averaging method, an algorithm calculates hourly concentrations by accounting for the time between value changes.
Daily
The hourly readings, from 1:00 am to 12 midnight, are summarised as daily data readings in scientific units. The table below lists the ways in which data is presented.
| Type of average used for hourly and daily web updates | Daily web updates made (using this type of average unless indicated otherwise) | Parameters updated |
|---|---|---|
| 1-hour average (AA1H) | Maximum of the 1-hour averages recorded for the day (i.e. between 01:00 and 24:00) | PM10 PM2.5 Ozone Sulfur dioxide Nitrogen dioxide Visibility |
| 24-hour average (AA24H) | Average of the 1-hour averages recorded for the day (i.e. between 01:00 and 24:00) | PM10 PM2.5 Sulfur dioxide |
| Rolling 4-hour average (RA4H): 4-hour average calculated for each hour of the day, where the time of the RA4H (e.g. 05:00) refers to the last hour of the averaging period (02:00-05:00). Note that the RA4H for 03:00 includes the hour 23:00 from the previous day up to 03:00 on the reported day. | Maximum of the rolling 4-hour averages recorded for the day (i.e. between 01:00 and 24:00) | Ozone |
| Rolling 8-hour average (RA8H): 8-hour average calculated for each hour of the day, where the time of the RA8H (e.g. 09:00) refers to the last hour of the averaging period (02:00-09:00). Note that the RA8H for 07:00 includes the hour 23:00 from the previous day up to 07:00 on the reported day. | Maximum of the rolling 8-hour averages recorded for the day (i.e. between 01:00 and 24:00) | Carbon monoxide |
| Rolling 24-hour average (RA24H): 24-hour average calculated for each hour of the day, where the time of the RA24H refers to the last hour of the averaging period. For example, the RA24H for 23:00 includes data from the previous day (23:00) up to the hour 23:00 from the reported day. | The arithmetic mean of 1-hour averages recorded for the day (i.e. between 01:00 and 24:00) | PM10 PM2.5 |