Sydney is world famous for its shimmering harbour and clear blue skies. Not this summer.

As bush fires ravage the country’s east coast, pollution is becoming a regular occurrence in Australia’s biggest city -- triggering health warnings and intensifying the debate about climate change in the worlds driest-inhabited continent.

Pockets of the city ranked worse than Shanghai on Thursday, with one suburb showing a very unhealthy reading of as much as 206, according to the World Air Quality Index, while Shanghai came in an unhealthy 160.

A separate index, compiled by the state government, rates anything above 200 as hazardous. Several parts of Sydney Thursday carried that highest warning, reaching as high as 622, and local authorities warned people to avoid outdoor exertion and stay indoors if possible, particularly those with heart and lung disease.

With summer barely underway, Sydneysiders are regularly waking up to their city clouded in a choking haze caused by smoke drifting from more than 100 bush fires burning in New South Wales state. Since the start of October, there have already been 17 days with hazardous AQI readings in the Sydney region, according to the states Department of Environment. Comparatively, there was only one day with a reading in excess of 200 during the states last fire danger season, from October 1, 2018 to March 31, and still none the period before that.

Sydneysiders should be bracing for more to come.

During the day, both Thursday and Friday, we are going to have winds generally westerly -- and as long as that fires there, that smoke is going to keep coming across, said Helen Kirkup, a meteorologist from the Bureau of Meteorology. The westerly, which is bringing in smoke from fires in the Blue Mountains region, might even bring some dust across from the west, just to add to the mix.

Even if the wind direction changes, Sydney still might not catch a break. Northerly and southerly winds would only serve to bring up different smoke.

The ferocious and early start to the fires this year has stoked a debate around whether Australia’s government -- a champion of the coal industry -- is doing enough to curb greenhouse gas emissions. On Monday, a woman whose home was burnt down in the recent fires dumped some charred remnants on the lawns of Parliament House in a plea for action on climate policy.

Prime Minister Scott Morrison has repeatedly shut down claims that his governments approach to climate change has contributed in any material way to the current bushfire emergency.