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Air quality: How bad is Sydney's smoke for health? Australia bushfires: Pollution concerns for tennis tournament
(about 2 months later)
Millions of people in Sydney are among residents across Australia who have been blanketed by bushfire smoke in recent weeks. When tennis player Dalila Jakupovic was unable to complete her qualifying match for the Australian Open, which begins on Monday, she blamed the "unhealthy" air quality caused by fire smoke. Bushfires have been burning across Australia for weeks, causing air pollution which can be harmful to health.
Outside of immediate fire zones, should they be worried? How damaging is bushfire smoke? And can it really be worse than having a cigarette? Ms Jakupovic criticised the organisers for letting the match go ahead in those conditions, as she and several other tennis players experienced effects, including coughing and difficulty breathing, nausea and muscle cramps.
How harmful is bushfire smoke?
Breathing in smoke can cause irritation in the eyes, nose, throat and lungs. In more serious cases it can lead to hospital, especially for people with pre-existing respiratory conditions.
As trees, leaves and other ground vegetation burn, they release small particles of solid carbon, water vapour and gases including carbon monoxide.
Ultrafine particles of less than 2.5 micrometers - referred to as PM2.5 - pose the biggest risk to health because they can bury deep into the lungs and even enter the blood stream. This risks irritation, infection and an increased chance of heart attacks and lung disease.
Professor Francesca Dominici, a statistician who works on public health, conducted a recent study into the effects of exposure to particulate matter. She found it was linked to hospital admissions for a wider range of conditions than previously thought.
As well as the known effects on the lungs and heart, her team identified "new diseases including septicaemia which is a serious bloodstream infection... urinary tract infections and renal failure," she told ABC News.
Bushfire pollution does not typically do as much lasting damage as traffic or industry pollution, according to Associate Prof Brian Oliver, an expert in respiratory disease from the University of Technology, Sydney, because conditions often lift with a change in weather.
This means any breathing discomfort is mostly short-lived.
But because many fires have been burning for weeks, and authorities warn that there is no immediate end in sight, experts say this should now be treated as medium-term exposure.
Who is this affecting?Who is this affecting?
Bushfires have been burning across the country, often sending smoke over populated areas.Bushfires have been burning across the country, often sending smoke over populated areas.
Residents of Sydney - Australia's largest city - have endured smoke for weeks. The city's air quality has exceeded "hazardous" levels on several occasions.Residents of Sydney - Australia's largest city - have endured smoke for weeks. The city's air quality has exceeded "hazardous" levels on several occasions.
That's led to a 10% rise in hospital admissions, say officials. Paramedics have treated hundreds of people for breathing problems. That has led to a 10% rise in hospital admissions, say officials. Paramedics have treated hundreds of people for breathing problems.
Adelaide - a city of 1.3 million - was also affected last month with its residents told to stay indoors. Adelaide - a city of 1.3 million - was also affected last month, with its residents told to stay indoors.
How harmful is bushfire smoke? Because PM2.5 particles found in bushfire smoke are so small - a ninth of the size of a grain of sand - they can travel huge distances on the wind, potentially affecting many more people. The smoke is expected to make "at least one full circuit around the globe," according to the US space agency Nasa.
Bushfire smoke is not as bad as industrial pollution but it is still harmful, says Associate Prof Brian Oliver, an expert in respiratory disease from the University of Technology, Sydney. Most vulnerable are children, the elderly and smokers, while those with asthma, heart and lung problems can see exacerbated symptoms - such as chest tightness and difficulty breathing.
"Any smoke that is produced as the by-product of something burning is noxious and bad," he tells the BBC. And, as competitors in the Australia Open tennis tournament have experienced, athletes can be more susceptible to smoke damage because they are breathing in larger volumes of air as they exercise.
It comes largely from natural sources - trees, leaves and other ground vegetation - and comprises small particles, gases and water vapour. The more intense the exercise, the more extra air will be taken in.
The gases include carbon monoxide, carbon dioxide and nitrogen oxide - all are most present nearer to a fire. Standard face masks are ineffective when it comes to blocking out fine particles, according to health authorities. They warned people to avoid exercising outdoors this week - a suggestion that many have ignored.
In Sydney - which has received smoke from blazes 150km (93 miles) inland - most danger lies in "ultrafine" particles which can travel vast distances on the wind. How bad has Australia's air quality been?
How bad has Sydney's air quality been?
Fine particle matters - known and measured globally as PM2.5 - are invisible to the human eye. They are coated in chemicals such as lead and are most worrying because they penetrate deep into the lungs.
Australia's clear air standard is a PM2.5 level of eight micrograms per cubic metre. By comparison, smoking a single cigarette produces 20 micrograms per cubic metre.Australia's clear air standard is a PM2.5 level of eight micrograms per cubic metre. By comparison, smoking a single cigarette produces 20 micrograms per cubic metre.
Recent readings in Sydney have been as high as 734 micrograms - the equivalent of about 37 cigarettes.Recent readings in Sydney have been as high as 734 micrograms - the equivalent of about 37 cigarettes.
And for firefighters and even some people who live closer to the blazes, exposure would have been "10-15 times higher", says Associate Prof Oliver.
"You have to feel for those people out there in those conditions," he said.
In some areas of Sydney, the air quality index - which takes in the particle reading, ozone levels, and other chemicals - has also exceeded Delhi's pollution when it reached "unbearable" levels last month, he added.
What is the impact on health?
In these circumstances, even healthy people can have small breathing issues and feel irritations in the eyes, nose, throat and lungs.
Most sensitive are children, the elderly and smokers, while those with asthma, heart and lung problems can see exacerbated symptoms - such as chest tightness and difficulty breathing.
Standard face masks are ineffective when it comes to blocking out fine particles, according to health authorities. They warned people to avoid exercising outdoors this week - a suggestion that many have ignored.
But this breathing discomfort is, fortunately, mostly short-lived, says Associate Prof Oliver.
Bushfire pollution does not typically do as much lasting damage as traffic or industry pollution - because conditions often lift with a change in weather.
However many fires have been burning for weeks, and authorities warn that there is no immediate end in sight. If the smoke lingers, then the particles could eventually have the same effect as cigarettes.
"A cigarette is basically a plant that we purposely inhale. And in bushfires, it's another plant that we're inhaling the smoke from, so it's not surprising the health effects are actually quite similar," said Associate Prof Oliver.
What about 'thunderstorm asthma'?What about 'thunderstorm asthma'?
Smoke is an obvious health hazard that can travel vast distances from the fire front. But the weather stoking the flames has created other issues too, such as dust storms.Smoke is an obvious health hazard that can travel vast distances from the fire front. But the weather stoking the flames has created other issues too, such as dust storms.
In Victoria, officials issued an "extreme" warning in November for a phenomenon known as "thunderstorm asthma".In Victoria, officials issued an "extreme" warning in November for a phenomenon known as "thunderstorm asthma".
This is where strong winds create more pollen in the air, which can lead to an outbreak of asthma attacks. In 2016, nine people died in Melbourne from such an outbreak. This is where strong winds create more pollen in the air, which can lead to an outbreak of asthma attacks. In 2016, nine people died in Melbourne from just such an outbreak.
Reporting by the BBC's Frances Mao Bushfires can actually create their own weather systems, which may exacerbate this effect, according to Rachel Badlan, a researcher at the University of New South Wales.
If it covers a large enough area, the upward movement of hot air from a fire can interact with the atmosphere and form a pyrocumulonimbus - a cloud of smoke, ash and water vapour which comes alongside massive thunderstorms.
Pollutants from these storms are flung into the stratosphere - more than 10km into the earth's atmosphere - according to Nasa.
Reporting by the BBC's Frances Mao. Additional reporting by Rachel Schraer.