I am sure we would all be happy to breathe the sort of air one finds in remote forests. Obviously, that is not a realistic expectations in the areas where most Australians live which are major cities. On the other hand, we also don't want to breathe air that is so polluted that it makes us sick, no matter where we live.
To balance this, the state and federal governments have jointly produced the national air quality standard. The official name of this standard is the "National Environment Protection (Ambient Air Quality) Measure". I am declaring right here that I am not qualified to judge the adequacy of this standard. All I ask with regards to air quality in Sydney is, exceptional events such as bush fires aside, that we meet this standard, nothing more, nothing less.
Before WestConnex, some air quality monitoring was undertaken to measure pre-existing air quality. One monitoring station was in West Botany Street, near the intersection with Marsh Street. It turns out that air quality was already not meeting targets, even before construction started.
Breaches of annual target for PM2.5: For the ten months for which I have data, the PM2.5 average (particles smaller than 2.5 microns in diameter), was 11.13 micrograms per cubic meter. This exceeds the national standard which specifies a maximum yearly average of 8. In my calculation, I have taken into account the different length of the months but not worried about cases where for one reason or another there are a few days without data. It does not matter that I only have 10 months of data, because even if I assumed that there was no pollution at all in the other two months, the average would still be 9.27 micrograms per cubic meter.
Breaches of daily target for PM 2.5: There were two months were the daily target was exceeded, January and May 2016. The June report blames the exceedances for the month on burn-offs. Those sort of events don't really count. However, on January 2, there was an exceedance of the PM2.5 target for which the report only stated: "High values were recorded on this day at other New M5 sites." I am counting this one as a genuine exceedance as as no reason was given. Perhaps weather conditions were such that pollutants dispersed less readily than usual.
| Month | PM2.5 monthly average, μg/m3 (yearly allowed average is 8) | PM2.5 highest 24 hours period, μg/m3 (allowed is 25) | PM10 monthly average, μg/m3 (yearly allowed average is 25) | PM10 highest 24 hours period, μg/m3 (allowed is 50) |
|---|---|---|---|---|
| September, 2015 | 10.8 | 14.7 | 20.2 | 34.4 |
| October, 2015 | 13.0 | 19.8 | 28.3 | 41.9 |
| November, 2015 | 10.2 | 19.0 | 22.4 | 46.0 |
| December, 2015 | 13.6 | 23.1 | 25.4 | 43.9 |
| January, 2016 | 7.9 | 26.3 | 20.7 | 32.5 |
| February, 2016 | 7.5 | 18.5 | 20.5 | 32.9 |
| March, 2016 | 8.6 | 15.7 | 15.9 | 27.5 |
| April, 2016 | 13.5 | 24.1 | 21.2 | 32.4 |
| May, 2016 | 16.1 | 39.3 | 25.8 | 54.1 |
| June, 2016 | 9.9 | 17.9 | 15.6 | 26.0 |
| Daily Target Exceedances | ||
|---|---|---|
| Reason in reports | Pollutant | Days |
| No reason given | PM2.5 | 2/1/2016 |
| Hazard reduction burning | PM2.5 | 8/5/2016, 9/5/2016, 10/5/2016, 20/5/2016, 23/5/2016, 24/5/2015 |
| PM10 | 23/5/2016, 24/5/2015 | |