Goals and limits
Monitoring types
The air quality goals and criteria for pollutants monitored at the WestConnex tunnel ambient monitoring sites are based on the following Conditions of Approval:
The air quality goals and criteria are shown in the table below:
| Monitoring type | Pollutant / parameter | Averaging period | Units of measurement | Limit / goal |
|---|---|---|---|---|
| External ambient | CO | 8 hours (rolling) | PPM | 9 |
| External ambient | NO2 | 1 hour | PPM | 0.125 |
| External ambient | PM2.5 | 24 hours | µg/m³ | 25 |
| External ambient | PM10 | 24 hours | µg/m³ | 50 |
| External ambient | Sigma Theta | 1 hour | º | N/A |
| External ambient | Temperature at 10 metres | 1 hour | K | N/A |
| External ambient | Temperature at 2 metres | 1 hour | K | N/A |
| External ambient | Wind direction | 1 hour | º | N/A |
| External ambient | Wind speed | 1 hour | m/s | N/A |
| In-tunnel | CO | 3 minutes (maximum value) | PPM | 200 |
| In-tunnel | CO | 15 minutes (maximum value) | PPM | 87 |
| In-tunnel | CO | 30 minutes (maximum value) | PPM | 50 |
| In-tunnel | NO2 | 15 minutes (maximum value) | PPM | 0.5 |
| In-tunnel | Visibility | 15 minutes (maximum value) | m-1 | 0.005 |
| Ventilation outlet | CO | 1 hour | mg/m³ | 40 |
| Ventilation outlet | NO2 | 1 hour | mg/m³ | 2 |
| Ventilation outlet | NOX | 1 hour | mg/m³ | 20 |
| Ventilation outlet | Solid particles | 1 hour | mg/m³ | 1.1 |
| Ventilation outlet | VOC | 1 hour | mg/m³ | 4 |
Traffic light status
We have developed a traffic light status for air quality based on the same values the Office of Environment and Heritage (OEH) use to display their Air Quality Index (AQI). The AQI is a scale of air pollution that helps people understand air quality and modify any activities if pollution levels are high. For further detailed description and explanation of the OEH AQI visit Understanding air quality for the Office of Environment and Heritage.
The traffic light status of each pollutant is shown in the 'Current snapshot' table for External Ambient, In-tunnel and Ventilation Outlet and it is based on the hourly reading relative to the limit or goal.
| Percentage of goal | Traffic light status |
|---|---|
| If reading is less than 67% of limit/goal | Good |
| If reading is greater than or equal to 67% and less than 100% of limit/goal | Fair |
| If reading is greater than or equal to 100% of limit/goal | Poor |