Air Quality
Air quality was assessed using data from three air quality stations around Darwin at Palmerston, Stokes Hill and Winnellie. Data are collected by the Department of Environment, Parks and Water Security. The measure of PM2.5 (particulate matter of 2.5 microns in size) was chosen as the most suitable measure for air quality affected by smoke haze in the Darwin Harbour region.
Scoring method
The percentage of daily non-exceedances (i.e. below standard) of the maximum human health standard of 25 μg/m3 were calculated for each air quality station (Palmerston, Stokes Hill, and Winnellie) for the period 1/1/2020 – 31/12/2020. The average of these percentages was used as the report card score.
Findings
The air quality parameter PM2.5 is a suitable indicator to represent deteriorated air quality due to bushfire smoke that is experienced annually in the Darwin Harbour region. This variability throughout the year is shown in the figure to the right with elevated PM2.5 levels between May and November, peaking in June. However, for 2020, there were 4 days where the average PM2.5 exceeded the National Environment Protection Measure (NEPM) standard of 25 µg/m3, resulting in 98.9% of the year meeting this air quality standard corresponding to a very good grade (A).
Additional information
Hourly background carbon dioxide (CO2) concentrations in ppm (parts per million) at Cape Grim, NW Tasmania, and Gunn Point, NT since January 2010. The global atmospheric growth rate and a seasonal cycle are evident in both data sets. There is greater variability and a larger seasonal cycle at Gunn Point compared to Cape Grim, due to active tropical ecosystems. Since commencing observations at Gunn Point in late 2010, background CO2 has risen by around 25 ppm.
