Fire alarms have been sounding in high-rise buildings across downtown Sydney and Melbourne as dense smoke from distant wildfires confuse electronic sensors. Modern government office blocks in the Australian capital Canberra have been closed because the air inside is too dangerous for civil servants to breathe.
The sun has glowed an eerie red behind a brown shrouded sky for weeks over Australian metropolitan areas that usually rank high in the world's most livable cities indexes.
It's an unprecedented dilemma for Australians accustomed to blue skies and sunny days that has raised fears for the long-term health consequences if prolonged exposure to choking smoke becomes the new summer norm. Similar concerns over smoke are emerging in other regions of the globe being impacted by more fires tied to climate change, including the Western U.S.
"I'm going to give birth any day now, literally, and I'm going to have a newborn baby that I'm going to protect from all this," said Emma Mauch, a pregnant Canberra mother.
Her friend, Sonia Connor, described the struggle of keeping her own energetic 3-year-old daughter contained inside their Canberra house with windows and doors sealed by tape as the outside temperature exceeded 42 degrees Celsius (108 degrees Fahrenheit). It's a choice between air flow in stifling heat or keeping potentially toxic smoke out.
"My daughter hasn't shown any sort of symptoms, let's say. For me, I can feel it in my lungs, my throat has felt weird," Connor said.
"It doesn't seem to be stopping her, but the long-term effects? Who knows? She's 3. Who knows what's going to happen?" she added.
Slovenian tennis player Dalila Jakupovic fell to her knees in a coughing fit on Wednesday while competing in a qualifying match for the Australian Open in Melbourne.
"I've never experienced something like this," Jakupovic told Australian Broadcasting Corp.
"We are used to pollution — like, we play in China and more polluted countries — but this smoke is something different that for sure we're not used to."
Canberra as well as Australia's two largest cities, Sydney and Melbourne, have at various times in recent weeks rated as the most polluted cities in the world, although some argue the industrial pollutants in places such as New Delhi are more dangerous than wood smoke.
The fires have claimed at least 27 lives since September, destroyed more than 2,600 homes and razed more than 10.3 million hectares (25.5 million acres), mostly in New South Wales state. The area burned is larger than the U.S. state of Indiana.
Hospital admissions have increased in the smoke-affected cities, with some patients suffering asthma for the first time in their lives. The government has responded by distributing 3.5 million free particle-excluding masks.
Acting Australian Chief Medical Officer Paul Kelly said he was discussing with the government launching a study of the long-term health implications of the wildfire smoke.
Bruce Thompson, president of the Thoracic Society of Australia and New Zealand, is among the respiratory disease experts who predict increases in heart and lung diseases as well as some cancers if climate change makes prolonged exposure to wildfire smoke an annual phenomenon.
"We're breathing in stuff that the lungs don't like that leads to significant changes, especially people who are predisposed to respiratory conditions," Thompson said.
Thompson, who suffers itchy eyes and a running nose from smoke at home in Melbourne, said comparisons could be drawn between the current crisis and a wildfire that ignited coal in the open-cut Hazelwood mine near the town of Morwell in Victoria state in 2014. The fire burned for 45 days, blanketing Morwell and its 14,000 residents in thick smoke and coal dust.
That exposure was still taking tolls on the health of the Morwell community and the wider Latrobe Valley, particularly the young, Thompson said.
Brian Oliver, head of the Respiratory Molecular Pathogenesis at University of Technology Sydney, likened prolonged and repeated exposure to such wildfire smoke to smoking cigarettes.
Oliver predicted increases in smoker diseases across Australia if the wildfire smoke became more common in a drier and hotter future.
NASA says the unprecedented masses of Australian smoke that have drifted east across the Pacific Ocean have returned after circumnavigating the globe.
In the U.S., an estimated 20,000 premature deaths now occur annually due to chronic wildfire smoke exposure. That's expected to double by the end of the century, according to scientists funded by NASA, as tens of millions of people get exposed to massive "smoke waves" emanating from blazes in Western states.
Experts say an increase in serious health problems in California may be almost inevitable for vulnerable residents as the disasters become more commonplace.
Research suggests children, the elderly and those with existing health problems are most at risk.
Short-term exposure to wildfire smoke can worsen existing asthma and lung disease, leading to emergency room treatment or hospitalization, studies have shown. Increases in doctor visits or hospital treatment for respiratory infections, bronchitis and pneumonia in otherwise healthy people also have been found during and after wildfires.
Some studies also have found increases in ER visits for heart attacks and strokes in people with existing heart disease on heavy smoke days during previous California wildfires, echoing research on potential risks from urban air pollution.
For most healthy people, exposure to wildfire smoke is just an annoyance, causing burning eyes, scratchy throats or chest discomfort that all disappear when the smoke clears.
Wood smoke contains some of the same toxic chemicals as urban air pollution, along with tiny particles of vapor and soot 30 times thinner than a human hair. These can infiltrate the bloodstream, potentially causing inflammation and blood vessel damage even in healthy people, research on urban air pollution has shown. Studies have linked heart attacks and cancer with long-term exposure to air pollution.
Whether exposure to wildfire smoke carries the same risks is uncertain, and determining harm from smog versus wildfire smoke can be tricky. There is little known about the long-term effects of wildfire smoke because of difficulties in studying populations years after a wildfire.
Michael Abramson, professor of epidemiology and preventive medicine at Melbourne's Monash University, is a co-author of a report on the ongoing investigation of the health impacts of the Hazelwood blaze.
Abramson urges a national study of the health impacts of the latest wildfires, saying his research focused on a much smaller population of 74,000 people in the Latrobe Valley.
"We're now seeing substantial exposure extending over weeks to cities that have millions of inhabitants, so I think it's very likely that there might be more subtle effects that we haven't been able to detect," Abramson said.
The political party Australian Greens called on the government to establish a climate emergency national medical stockpile to prepare for future bushfire crises.
Richard Di Natale, the leader of the Greens, said that under his plan the stockpile would include smoke-filtering masks.
The air quality in Melbourne on Tuesday morning dropped to hazardous levels, as smoke from Victoria's northeast fires blanketed the state.
"It's almost impossible to avoid. It can claim lives, and it hurts everyone's quality of life," Di Natale said, according to The Sydney Morning Herald report on Monday evening.
"Already one person has died in Canberra, and the public health impacts on the broader population won't be known for months."
The government has an existing stockpile with 1.8 million masks available, but the Greens demanded a significant expansion.
Retailers across the country have sold out of P2 masks, which filter out hazardous smoke particles, forcing them to order hundreds of thousands more.
Wesfarmers, the owner of hardware giant Bunnings, earlier in January said that demand for the masks was "through the roof."
"The Australian Greens are launching the climate emergency national medical stockpile to reflect the immediate risk to people's health," the Greens said in a statement.
"It will give people an assurance that their government has the ability to respond to the health impacts of the fire crises, without running into the widespread mask shortages we have seen since December."
Greg Hunt, minister for health, has promised that the government will make more masks available as demand rises.
Crews battling Australia's wildfires said Sunday that they have been able to turn from defense to offense for the first time in weeks thanks to a break in the weather.
Dale McLean, who is helping manage the response to a fire near the town of Bodalla in New South Wales state , was part of team that was bulldozing down small trees and burning scrub ahead of the fire's projected path to try to stop it from reaching a major highway by starving it of fuel.
"This fire took a major run about seven or eight days ago, and with the weather changing now, the weather settling down, the fire has settled down," he said. "The fire behavior has changed. So we're able to get in front of the fire now, get on the offensive."
Other workers echoed McLean's comments, saying cooler temperatures and mild winds have finally offered them a chance to make progress. The weather is expected to remain benign for the next week, although any deterioration in conditions after that could see the wildfires flare up again.
The progress came after a firefighter was killed by a falling tree. Bill Slade — one of the few professionals among mainly volunteer brigades battling blazes across southeast Australia — died on Saturday near Omeo in eastern Victoria state, Forest Fire Management Victoria Executive Director Chris Hardman said.
The 60-year-old married father of two was commended in November for 40 years of service with the forestry agency.
"Although we do have enormous experience in identifying hazardous trees, sometimes these tree failures can't be predicted," Hardman said. "Working on the fire ground in a forest environment is a dynamic, high-risk environment and it carries with it significant risk."
The tragedy brings the death toll to at least 27 in a crisis that has destroyed more than 2,000 homes and scorched an area larger than the U.S. state of Indiana since September. Four of the casualties have been firefighters.
The crisis has brought accusations that Prime Minister Scott Morrison's conservative government needs to take more action to counter climate change, which experts say has worsened the blazes. Thousands of protesters rallied Friday in Sydney and Melbourne, calling for Morrison to be fired and for Australia to take tougher action on global warming.
The prime minister said Sunday that his government was building resilience to the fire danger posed by climate change.
He said the government was developing a national disaster risk reduction framework within the Department of Home Affairs that will deal with wildfires, cyclones, floods and drought.
"This is a longer-term risk framework model which deals with one of the big issues in response to the climate changing," Morrison said.
He said his government accepted that climate change was leading to longer, hotter and drier summers, despite junior government lawmaker George Christensen posting on social media over the weekend that the cause of the latest fires was arson rather than man-made climate change. Another junior lawmaker, Craig Kelly, has also publicly denied any link between climate change and fire crisis.
State authorities have said a minority of fires are deliberately lit.
"The government's policy is set by the Cabinet. Our party room has a broad range of views," Morrison said of those within government ranks who reject mainstream climate science.
Morrison also announced that 76 million Australian dollars ($52 million) would be spent on providing psychological counseling for firefighters and fire-affected communities as part of a previously announced AU$2 billion ($1.4 billion) recovery fund.
"There has been a deep scar in the landscape that has been left right across our country," Morrison said. "But I am also very mindful, as is the government, of the very real scars that will be there for quite a period of time to come for those who've been exposed to the trauma of these bushfires."
While the fire threat is most acute in rural communities, wildfire smoke that has choked some of Australia's largest cities is a reminder to many urban Australians of the unfolding disaster.
With flames climbing as high as a 15-story building and menacing his supposedly fireproof home on three sides, Justin Kam ran to the laundry room and opened the door. Inside was fire.
That's not supposed to happen, he thought.
It was clear his family's fortress had been breached and they were in mortal danger and needed to get out.
"Once the fire had penetrated the structure, that was the signal: Time to get out. You can't save it," he said. "Staying in any longer and we really would've been a statistic."
They escaped — just barely — but found themselves among 2,000 homeowners whose houses have burned down during what has been been a catastrophic fire season Down Under, full of apocalyptic images that have focused the world's attention on climate change.
The blazes have killed at least 25 people, scorched an area twice the size of the U.S. state of Maryland and killed hundreds of millions of animals and birds. The fires are expected to flare up later this week when temperatures rise.
Kam and his wife, Helena Wong, had built their home in the New South Wales town of Balmoral with steel framing, reinforced glass so thick you would need a sledgehammer to break it and retaining walls made of rock, all to protect them from Australia's notorious wildfires.
Their defenses turned out to be no match for a rapacious fire so hot it evaporated their outdoor furniture, leaving behind ghostly imprints reminiscent of those after the atomic bombing of Hiroshima.
Justin and Helena had moved to their sleepy village of 400 people 20 years ago and thought they had found their slice of paradise. Their house overlooks a valley filled with eucalyptus trees. Kangaroos hop along their veranda, and a wombat dug a burrow under their deck. Helena began breeding rare chickens.
They knew the fires would come, and had successfully fought two before.
On Dec. 21, Justin was ready, watching the progress of the flames from his roof with binoculars. The couple and their 16-year-old son, Gabriel, who was on Christmas break from school, had been raking and wetting down the areas around the house. The had filled buckets, emptied gas cylinders, put on their smoke masks and left two vehicles running in the driveway, just in case.
But this fire was like nothing they had ever seen. A wall of flame came up the valley. A fireball rose 60 meters (200 feet) into the sky. The flames were so hot they were swirling, and not only moving with the wind, but also against it.
The family raced to douse embers on one side of the house only to find the flames approaching from a different direction.
"It operated like a military tactician," Justin said. "It would hit you from the front, and while you're occupied with that, it would turn around and hit you from the flanks."
The fire killed a half-dozen lizards that took refuge in a pot of water and all of Helena's chickens. When the flames burst into the house, they melted a champagne bottle, fusing it with some buckled porcelain and a sushi knife.
As the family members ran from their house, Helena's shoes melted and embers landed on her shoulders. She believes they made it out by no more than 30 seconds. The back of their car had melted, so they jumped into their truck and drove up their driveway to the end of their street.
But there was nowhere to go from there. They were surrounded by flames.
After what might have been five minutes or 10, the fire front moved on and they drove to the fire station, where others were taking shelter.
Among them was Rosemary Doyle, whose own house had burned down. The fire station itself was under threat, and people began to pray, even the atheists among them. The power went out, and Doyle crawled out from the bathroom, thinking: Not today. Not yet. It's not my time.
On Tuesday, Brendon O'Connor, the town's volunteer fire captain, said that while the fire had moved on from Balmoral, where it burned down about 25 homes, he doesn't know when it will stop.
"Either when the good Lord opens up the heavens and gives us weeks of rain, or it burns to the coastline," he said. "They're really the options. It really is too large to put out. Anything that we're doing isn't working."
O'Connor on Tuesday attended the funeral for one of two volunteer firefighters killed by a falling tree while driving to Balmoral to help battle the blaze.
When Justin and Helena returned to their burned-out home, they found a piece of pink chalk and used it to write on their wall, "We'll be back!"
But it will be a long struggle. They are finding it difficult to navigate through all the red tape, and they didn't have insurance on their house. Justin, a woodworker who built all the family's furniture, said that was because they had other financial priorities, such as school fees and looking after aging relatives.
"We had our plan in place, but still, it spanked us like little naughty children," Justin said. "That's Mother Nature for you."
Thunderstorms and showers brought some relief for firefighters battling deadly wildfires across Australia's drought-parched east coast on Wednesday, but also raised concerns that lightning will spark more fires before dangerous hot and windy conditions return.
Around 2,300 firefighters in New South Wales state were making the most of relatively benign conditions by frantically consolidating containment lines around more than 110 blazes and patrolling for lightning strikes, state Rural Fire Service Commissioner Shane Fitzsimmons said.
"Unfortunately with lightning strikes, it's not always the next day they pop up," Fitzsimmons told the Australian Broadcasting Corp.
"They can smolder around in trees and in root systems for a couple of days and pop up under drier, hotter conditions, so we are very mindful of that as we head into Friday," he added.
The unprecedented fire crisis in southeast Australia that has killed 25 people, destroyed 2,000 homes and shrouded major cities in smoke has focused many Australians on how the nation adapts to climate change. Prime Minister Scott Morrison has faced fierce criticism both domestically and internationally for downplaying the need for his government to address climate change, which experts say helps supercharge the blazes.
The center-left opposition Labor Party has made political capital from the crisis by promising more ambitious policies than the ruling conservative coalition to tackle climate change. Opposition climate spokesman Mark Butler wants the government to allow a debate on climate change in Parliament when it returns in February.
"Hopefully we could fashion a bipartisan position," Butler told ABC. The two sides last held a bipartisan position on climate change in 2007, and have remained bitterly divided ever since on issues such as making carbon polluters pay for their emissions.
Labor had pledged to reduce Australia's greenhouse gas emissions by 45% below 2005 levels by 2030 and achieve zero emissions by 2050 if it had won last year's elections.
The coalition government has committed to reduce emissions by 26% to 28% by 2030 and warns that Labor's more ambitious target would wreck the economy. The government argues that Australia is responsible for only 1.3% of global emissions and more ambitious targets would not ease the current fire crisis, which follows Australia's hottest and driest year on record.
The unfolding disaster in Australia, which is likely to continue throughout the Southern Hemisphere summer, has galvanized calls for more global action on climate change.
Elton John and actor Chris Hemsworth are among the celebrities donating big bucks to help aid the firefighting efforts. Hemsworth, an Australian who lives in the drought-affected New South Wales town of Byron Bay, wrote on Twitter that he was donating $1 million and asked his followers to show support. "Every penny counts," he wrote.
John announced during his Farewell Yellow Brick Road concert in Sydney on Tuesday that he will also donate $1 million. The singer said he wanted to bring attention to the devastation that wildfires have caused, saying it has reached a "biblical scale."
Hemworth and John joins a growing list of celebrities, including Pink, Nicole Kidman and Keith Urban, who have pledged to donate toward relief efforts.
Prince Charles, who is next in line to become the British monarch and king of Australia, said in a video message from Scotland that he and his wife Camilla had been in despair watching the infernos burn across Australia.
"I fear this is a hopelessly inadequate way of trying to get a message to all of you that both my wife and myself are thinking of you so very much at such an incredibly difficult time and in such impossible and terrifying circumstances," the prince said.