Challenging day ahead in NSW, SA and Queensland as the RFS mourns volunteers

A firefighter at Balmoral, 150km south-west of Sydney where an out of control fire destroyed a home on Thursday. Gusty conditions pushed heat and smoke across greater Sydney. Photo / RNZ / AFP

An already difficult day for firefighters has ended in tragedy as two RFS volunteers were killed when their truck rolled southwest of Sydney.

Three others are in hospital from the accident and two more firefighters are in a coma after being overcome by flames in a separate incident.

Firefighters are in for a tough day right around the country with Queensland facing terrible conditions and South Australia set to have its worst fire risk day of the summer with catastrophic conditions declared across the state.

Meanwhile, Sydney has again been blanketed in smoke as bushfires burning on the outskirts of the city cause the air quality to plummet.

The smoke from the fires has been so thick it was visible on the Bureau of Meteorology radars before 9am.

One Twitter user posted a comparison of the sky from Melbourne to Brisbane.

While Sydney's air quality isn't as bad as it was on December 9 – when thick bushfire smoke threw the city into chaos – the air quality index (AQI) was still deemed as "hazardous". A hazardous reading is anything above 200.

Between 11am and noon today, parts of Sydney's AQI were more than three times the hazardous level with the city's southwest hitting levels above 700.
Readings for the P2.5 particles, the ones that can enter the bloodstream and have health impacts, are also unhealthy.

How good is Sydney harbour? #sydneysmoke #NSWbushfires #sydneyfires #wherethebloodyhellareya pic.twitter.com/qIPNKwFK1r

— Adam Marsters (@AdamMarsters) December 19, 2019

In Camden, in the west of Sydney and near the Green Wattle Creek fire, P2.5 readings are close to 200. A good reading, where no health impacts are expected, is typically under 100.

#SydneySmoke is also trending on Twitter with thousands of people sharing pictures of the hazy city.

Sydney was brought to its knees on December 9 when thick bushfire smoke blew into the city's basin.

Offices around the CBD were evacuated as the conditions caused dozens of fire alarms to go off and the smoke wreaked havoc with public transport as well.

Also the air quality in Sydney is shocking again - normal view vs today #sydneysmoke pic.twitter.com/7eEN88jFYy

— Christina - Hair Romance (@HairRomance) December 19, 2019

Ferries were cancelled due to poor visibility and fire alarms went off at stations, causing Opal card readers to become inactive.

That day, Sydney's air quality index had deteriorated to a staggering extent, exceeding 2000 in some areas.