Sydney was wrapped in a thick toxic fog Tuesday, November 19, fueled by fires that devastate the east coast of Australia since last Friday.

Pollution levels have reached "dangerous" thresholds in Sydney according to official figures. The highest concentrations of PM 2.5 fine particles reaching up to 186 parts per million in the northwest of the city, rates comparable to those observed in the Indian capital New Delhi. Residents were instructed to avoid outdoor physical activity.

Fine particles can irritate the respiratory system and aggravate pre-existing cardiac and pulmonary problems, said New South Wales State Director of Environmental Health Richard Broome.

Nearly 140,000 hectares of bush burned

The fog that envelops Sydney, the capital of New South Wales (southeast), comes largely from a gigantic bushfire ravaging two national parks, some 100 kilometers northwest of the city.

The fire has been raging for several days, and has already burned nearly 140,000 hectares of bush. Six people have died and hundreds of homes have been destroyed in the states of New South Wales and Queensland since the start of the fire season in September.

Higher temperatures, around 40 degrees Celsius, as well as strong winds and low humidity are expected, increasing the risk of fires for Wednesday. More than 110 fires are still active. Hundreds of homes have been damaged or destroyed, and over a million hectares of vegetation have been burned.

Such fires occur every year on the immense island-continent during the austral spring and summer. But this year, the fire season was particularly early and violent and could be one of the worst recorded in the country.

With AFP