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Author: State of the Environment 2023

On 12 March 2020, the South Australian Government implemented lockdown measures until the end of April 2020. The measures were expected to reduce air pollution due to decreased non-commercial vehicle traffic and decreased industrial and commercial activity. The average reduction in traffic volume was 40% during the peak of the restrictions before returning to near-normal levels at the end of July 2020.

In the Adelaide CBD, levels of CO decreased by 40% in accordance with the traffic volumes, compared with measurements taken during the same period (March–April) in the 5 years before the COVID-19 lockdowns. Evidence of decreases in NOx and PM2.5 was harder to observe.

Five years of data were used for the pre-pandemic period to reduce the influence that large-scale events, such as bushfires and land burns, can have on estimates of ambient pollutant concentrations. This resulted in a small reduction in NOx levels. PM2.5 levels continued to be influenced by bushfire smoke in the early part of 2020 and remained very similar to past averages. Overall, an improvement in air quality was recorded, with 20–40% reduction in all pollutants during March and April 2020.

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