The air quality in Sydney is the equivalent of smoking 34 cigarettes a day

Chunks of black ash started raining down on Sydney today as the sky turned an apocalyptic shade of orange amid catastrophic bushfires west of the city.

The Harbour City has been covered in a thick blanket of smoke for weeks as bushfires burn on the city's fringe, including in the Blue Mountains.

But millions of residents woke up this morning to find a fresh layer of ash coating their homes and cars.

One Twitter user posted a video of their work desk littered with black pieces of ash.

One Twitter user posted a picture of their work desk covered in black ash

Another uploaded a pictured of a white outdoor table dotted with embers.

Someone else said: 'Poor air quality, it's raining ash. Sydney is choking!'

The city's air quality is said to be the equivalent of smoking 34 cigarettes a day.

More people are stepping out wearing masks and experts now say the air quality of the city is worse than in India's congested Delhi.

Meteorologist Sarah Chadwick told Daily Mail Australia while there may be a short reprieve over the weekend, Sydneysiders were in it for the long haul, with the smog expected to continue into January.

Sydney Harbour is covered in a thick layer of smoke as black ash rains down from the sky

Another social media user posted a picture of their outdoor table dotted with chunks of ash

'We're going to see the winds turn easterly over the weekend, which could reduce the smoke for a little but, but it wont be sustained until we put the fires out,' she said.

'The main thing we need is a good soaking, and we don't have any on the horizon at the moment.

'Through the month of December, we're more likely to see less than average rain. [The issue] is not quite as pronounced in January, but [the rainfall levels are] still quite low.'

Ms Chadwick said the amount of smoke sitting over the city depended on current fire activity, and she did not believe anyone could give a definitive answer on when the blazes raging across the state might be extinguished.

The sun turned bright red, as seen in a picture by a social media user in Sutherland in Sydney's south

Ash raining down from the sky under a bright red sun in Hurstville in Sydney's south

Meanwhile residents have suffered through the longest and most widespread period of poor air quality in the state's recorded history.

NSW Health revealed in the week ending on December 1, 1126 people presented at emergency departments across the state, and 2214 people called an ambulance reporting they had trouble breathing.

Strong westerly winds expected until Saturday will further hinder firefighters efforts, with hot and dry conditions set to exacerbate the situation.

Communities in fire-prone areas are urged to prepare their homes 'while they still have time' and to ensure they're prepared themselves in the event of a fire.

