Explained: Why Australia's Sydney Is Engulfed In Smoke For Days

The city of Sydney in Australia is currently engulfed in thick wood smoke resulting from the hazard reduction burns ahead of the wildfire season. The Australian city's air quality readings have been among the worst in the world over the past four days after the authorities undertook controlled burning of fuel loads.

According to a report by news agency Associated Press, the city's fire authorities have carried out only 14% of the planned burning in New South Wales. These hazard-reduction burns will continue over the next week or so ahead of the expected hot and dry summer in the Southern Hemisphere.

What the authorities say

On Thursday, the planned burns were suspended after the city witnessed excessive pollution levels and deteriorated air quality. New South Wales Rural Fire Service Inspector Ben Shepherd said the process had to be postponed due to excessive smoke that enveloped the city, adding that the department would let the smoke clear out over the next 48 hours.  

Last week, the burns couldn't be carried out because of the rain. The authorities anticipate an increased fire danger due to rising temperatures and windy conditions late next week, meaning it will delay the burns again.

The Black Summer of 2019-20

At least 33 people, including 10 firefighters, were killed in the catastrophic Black Summer wildfires of 2019-20. The fires destroyed 3,000 homes, razed 19 million hectares (47 million acres) and displaced thousands. The resulting smoke also led to the death of 400 people in all major cities in the region.

This year, the authorities expect the upcoming wildfire season across southeast Australia to be the most destructive 2019-20 fires.

What happened in the last few years

Post the Black Summer of 2019-20, the region has seen unusually wet and mild summers in three successive years. Last year, only 24% of the planned hazard reduction burns were carried out in New South Wales due to rains. It also created larger fuel loads for this year, becoming a source of frustration for authorities.