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Sydney under blanket of smoke as hazard reduction burnings spread citywide air pollution

Controlled burnings northwest of Sydney Australia sharply increase air pollution in the city. Read all about the “Sydney smoke” and its effect on air quality.

Sydney has recently suffered from unusually high levels of air pollution due to planned burning activities nearby, which have sent a thick cloud of smoke over the city. The Sydney smoke created a hazy contrast to the city’s typically cleaner air.1

At its worst, Sydney air quality measurements reached over triple the Australian recommended annual guideline for fine particulate matter (8µg/m3), and in areas nearby including Liverpool, air pollution peaked at even higher levels, remaining over 35µg/m3 for almost a full 24 hours (equivalent to a health warning of “Unhealthy for Sensitive Groups” by US standards).2


Air pollution remains high throughout Monday in Liverpool
Air pollution levels remained high throughout Monday in the Sydney area


The smoke resulted from hazardous reduction burns—or controlled burnings—which are an established part of forest management.3 The blazes took place to the northwest of the city, across the Southern Highlands and Colo Heights, while the largest area burned was Heathcote, where a full 160 acres of the Royal National Park was ablaze.


Sydney's annual air pollution level during 2018 was a fraction of current conditions
Sydney's annual PM2.5 air pollution level during 2018 was only 7.6µg/m3 - a fraction of the pollution currently hanging over the city


Unfortunately for Sydney, the weather conditions which made this a perfect time to carry out these burnings also happened to be some of the worst weather conditions to exacerbate the impacts of smog. Cooler temperatures, lighter winds, and higher humidity help reduce the risk of wildfires spreading, but they also similarly make it harder for pollution to disperse.

As Sydney experienced an inversion, which helped to “trap” the smoke, and burnings continued for a week, residents had to follow air quality developments and take precautions to protect their health. To reduce your exposure to hazardous wildfire smoke, stay up-to-date with local readings using the IQAir Air Quality App, and when outdoor pollution levels are high, try to limit outdoor activities.

Article Resources

[1] Berlinger J, et al. (2019, November 11). Australia’s deadly bushfires bring threat of ‘long and dangerous day ahead’.

[2] Keywood M, et al. (2016). Ambient air quality: National air quality standards.

[3] Brook B. (2019, April 29). Hazard reduction burns lead smoke to settle across Sydney affecting air pollution.

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