The air quality in Melbourne's suburbs has dropped to the worst-rated level today, as smoke from bushfires in East Gippsland and the north-east continues to blanket the state.

Key points: Air quality across most of Melbourne's suburbs was rated as "hazardous" this morning

Air quality across most of Melbourne's suburbs was rated as "hazardous" this morning Victoria's chief health officer said he believed the city's air quality dropped to "the worst in the world" overnight

Victoria's chief health officer said he believed the city's air quality dropped to "the worst in the world" overnight Firefighters have been called out to nearly 200 false fire alarms overnight, largely due to the smoke

The pollution has forced pools and beaches to close, horse races to be cancelled, construction workers to abandon outdoor work and caused concerns about the welfare of tennis players at the Australian Open.

One emergency-level blaze is burning near the East Gippsland community of Tamboon, as emergency services attempt to contain huge fires still burning across the state.

Play at the Australian Open was delayed due to significant smoke haze and resumed an hour later when conditions improved.

The sun in Docklands was softened by smoke pollution this morning. ( ABC News: Simon Tucci )

Slovenian player Dalila Jakupovic had to abandon her qualifier mid-match when she fell to her knees coughing.

She was escorted from the court and the match was called off.

At the Kooyong Classic, a match between Maria Sharapova and Germany's Laura Siegemund was called off at five all.

The moderate to hazardous air quality is forecast to continue across much of the state on Wednesday.

Data published on the Environment Protection Authority's (EPA) AirWatch website this morning showed air pollution levels were "hazardous" across Melbourne's suburbs, from Melton in the west to Dandenong in the south-east and Macleod in the north.

It also reached hazardous levels in the state's second-biggest city of Geelong for the second time in two weeks, while the same rating was given to towns in the firegrounds such as Omeo and Orbost.

The picturesque beach at Dromana has been transformed by the smoke. ( Supplied: Adam Richmond )

The smoke affected visibility at Phillip Island. ( Instagram: @phillipislandtourist )

The EPA website struggled to cope with traffic this morning and has crashed several times.

One global ranking website suggested the air pollution in suburbs like Box Hill is among the worst in the world, behind only some cities in India.

Victoria's chief health officer Brett Sutton said he believed Melbourne's air quality had dropped to "the worst in the world" overnight as cooler temperatures brought particles in the air closer to the ground.

An eerie red sun set over Melbourne on Monday night. ( ABC News: Patrick Rocca )

The Metropolitan Fire Brigade (MFB) said it had been called out to 192 false alerts from fire alarms since 10:00pm yesterday, the majority of which were because of the smoke.

Ambulance Victoria said it responded to 110 callouts for people with breathing issues between midnight and 11:00am, two thirds more than normal.

Horseraces at Werribee were cancelled and several outdoor suburban swimming pools were closed due to the smoky conditions.

Geelong has experienced hazardous levels of smoke pollution. ( ABC News: Nicole Mills )

Many of the state's beaches, including those along the tourist-friendly Great Ocean Road, have also been closed due to fears that surf lifesavers will be unable to see swimmers in trouble.

Life Saving Victoria's manager of lifesaving operations, Liam Krige, said the closures were to protect the safety and wellbeing of both lifeguards and the public.

"Visibility of swimmers in the water is just one of the aspects that Life Saving Victoria's trained and dedicated lifeguards and volunteer lifesavers take into account when making assessments about beach safety," he said.

The closures mean that lifesavers are not actively patrolling the beaches and swimming is not recommended.

Victoria's construction union has also advised builders to stop all outdoor work, which has affected most sites, including high-rise developments.

A CFMEU spokesman said the smoke was not only a health issue for workers as they inhaled fine particles, but also posed a danger as it reduced on-site visibility.

The view from Sunshine train station was hazed with smoke this morning. ( Supplied: Adam Gemmell )

People living in an area with hazardous air quality are advised to limit their time outdoors and follow treatment plans if they suffer from respiratory conditions.

Dr Sutton said people in East Gippsland and the state's north-east, where poor to hazardous air quality is likely to remain for some time, should try to let fresh air into their homes when possible.

"When conditions are good … that's the time to open doors and windows to air your house, to get the smoke out and then when the air quality's poor, close doors and windows, stay inside, minimise your activity," he said.

Longford, just outside Sale, is among several Gippsland communities who have suffered poor air quality for weeks. ( ABC News: Mark Debono )

The EPA's air quality controller, Jason Choi, said the smoke would likely stay around Melbourne into Wednesday, when afternoon showers could see it clear.

Authorities have advised people with asthma, who are pregnant, over the age of 65 or under the age of 14 to try to limit their time spent in the smoke where possible.

"We generally don't get to these sorts of levels," Mr Choi told ABC Radio Melbourne.

The smoke has resulted in appalling air quality in most of Melbourne's suburbs, including Dandenong. ( Supplied: Tara Jarvis )

Victorian road authorities have urged motorists to keep their headlights on low-beam to ensure they can be seen, even during the day.

"You should keep your windows closed and switch your air-flow set to re-circulation to reduce the smell of smoke inside your car," VicTraffic said in a Facebook post.

The West Gate Bridge has been partially obscured by the thick smoke pollution. ( Supplied: Kevin Hinds )

State-wide shortages of face masks

Hardware chain Bunnings said supplies of P2 face masks were running low across the state and some stores had run out as Victorians sought to protect themselves from the smoke.

Wholesaler Metcash, which supplies Mitre 10, Home Timber & Hardware, Thrifty Link and True Value Hardware stores said demand for P2 face marks was "unprecedented".

Loading

"We currently have product available but it is selling very fast across all our network of independent stores," Metcash said in a statement.

"We have gone to great lengths, calling on all sources of supply to meet this unprecedented demand."

At Southbank, cyclist Luke Johnson told the ABC he had ridden into the CBD from Blackburn and only in the last kilometre had felt the smoke in his chest.

"I didn't think it'd be quite this bad," he said.

Gayle Cowling, who was walking to work, said she was struggling with the air, which smelled and tasted of smoke.

"It's just sad, with what's going on with the bushfires … if this is what it's like here, I can't even begin to imagine what it's like for them in the thick of it," she said.

ABC Radio Melbourne caller Trevor said he only had about 100 metres of visibility in some areas as he drove into Melbourne from the Mornington Peninsula this morning.

He said traffic had slowed down to about 40 kilometres per hour as he got closer to the city.

Australian Medical Association president Tony Bartone, who lives in Melbourne, said people who did not need to be outside should stay indoors.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 11 seconds 3 m 11 s The AMA has recommended Melburnians stay indoors if they can.

"You can feel it and you can see it and you can taste it in the air," he said.

Dr Bartone said the smallest pollution particles of less than 2.5 microns in size posed the greatest health risk, as they were able to bypass the body's defence mechanisms and settle deep in the lungs.

United States space agency NASA has predicted that the smoke from Australia's bushfires will lap the world and could make its way back over Australian skies in the coming days.

The tourist town of Lakes Entrance, which was evacuated at the start of the bushfire crisis, has had very poor air quality during the fires. ( Supplied: Marie Walker )

Firefighters in Victoria have been using milder conditions to their advantage this week as they work to contain massive bushfires across the Alpine region, East Gippsland and the north-east which have burnt 1.4 million hectares of land.

Smoke remains heavy over that region, as the second escorted convoy of people left the cut-off town of Mallacoota for New South Wales.

Police have said the Princes Highway into Mallacoota will likely remain closed for weeks as emergency services work to clear fire-damaged trees from the side of the road.

At a press conference this morning, Premier Daniel Andrews confirmed the Inspector-General for Emergency Management, Tony Pearce, would be given $2.55 million to hold an inquiry into the state's bushfire season.

The inquiry will consider the effectiveness of the state's response, the declaration of a state of disaster, the support from the Commonwealth Government, evacuation processes and the preparedness of the state going into the season.

Loading

Loading