How wildfire pollution may be harming your health
Smoke from burning forests and peat can linger in the atmosphere for weeks, travelling thousands of miles and harming the health of populations living far away.
From far above, they almost look beautiful. Golden yellow tendrils etched across the dark forest landscape below. But in daylight, at close range, the devastation wrought by the fires in the Krasnoyarsk region of Siberia is harrowing.
A wall of blistering flames engulfs the vegetation. Behind it, charred trees stand like blackened toothpicks while columns of smoke choke the air, rising high up into the atmosphere. Since the start of 2020, Russia has seen an estimated 19 million hectares (73, 359 square miles) consumed by wildfires, according to Greenpeace International’s analysis of satellite images. Nasa has warned that abnormally warm temperatures in eastern Siberia – particularly in the Sakha Republic, more than 1, 250 miles (2, 000km) away from Krasnoyarsk – have led to more intense and widespread fires than normal.
The destruction this leads to is undeniable. Swathes of forest and peatland are destroyed. Countless animals caught up in the flames and smoke perish. And when the flames reach areas inhabited by people, they can claim many lives and homes of those unlucky enough to be caught in their path.
In the first few months of 2020, Australia grappled with the worst wildfire season in its history. It claimed the lives of 33 people, destroyed thousands of homes and saw 18 million hectares (69, 500 square miles) burned. Three billion animals were killed or displaced. And this August, thousands of lightning strikes triggered hundreds of fires across California, leading to a state of emergency being declared as the flames threatened densly populated residential areas. Beset by a prolonged drought, the state experienced its most destructive and deadliest fires in recorded history during 2017 and 2018.
These impacts on the ground can be hard to bear, but wildfires can have another far-reaching effect on our lives.
Rising up to 14 miles (23km) into the air, well into the stratosphere, plumes of smoke from large wildfires can spread all over the globe thanks to currents of air. Smoke from this summer’s Siberian wildfires has been choking nearby cities for months now and has spread across the Pacific Ocean to reach Alaska. The smoke has even been reducing air quality by creating hazes in cities as far away Seattle.
The Arctic wildfires in Siberia this summer have set a record: for releasing more pollution into the air in a single month than any other in 18 years of record keeping, according to the European Centre for Medium-Range Weather Forecasts.
It is in part down to what’s burning – resin-rich boreal forest, peat buried in bogs and melting tundra permafrost all release high concentrations of carbon dioxide into the atmosphere along with methane and toxic contaminants such as mercury. But it’s also because the fires are more widespread – a byproduct of record-breaking heat waves that gripped the Arctic in early summer. This helped thaw parts of the tundra, making it much more susceptible to burning.
Carried with the gases released by wildfires, however, are also tiny, lightweight particles of soot. Such "particulate matter" (PM) is a common component in air pollution in cities, where it can be released from vehicle exhausts and heavy industry. But smoke from wildfires can lead to dramatic spikes in the amount of particulate matter in the air compared with average air pollution.
Wildfire causes episodes of the worst air quality that most people living in high income countries are ever going to see – Sarah Henderson
For example, during wildfire season in Canada, cities in British Columbia have seen particulate levels that are 20 times higher than would be expected on an average day.
"Wildfire causes episodes of the worst air quality that most people living in high income countries are ever going to see, " says Sarah Henderson, senior scientist in environmental health services at the British Columbia Center for Disease Control. The small size and large amount of particulate matter has a lot to do with this.
Wildfires tend to produce large quantities of finer particulates known as PM2.5 and even finer nanoparticles, which are known to be particularly harmful to human health. This is largely because the tiny particles – which are more 30 times smaller than the width of a human hair and so too small to see – can penetrate the lung membranes when breathed in, damaging the respiratory system and passing into the blood stream.
In the short-term, that can lead to coughing, shortness of breath and exacerbate asthma attacks. During the bushfires at the end of 2019 in Australia, hospital admissions due to breathing problems increased by 34% in the state of New South Wales.
One study estimated that between 2004 and 2009, around 46 million people in the western US were exposed to at least one wave of smoke from wildfires. On days where smoke had caused high PM2.5 levels, there was a 7.2% increase in hospital admissions due to respiratory illnesses. Increases in PM2.5 have also been found to be accompanied by a spike in cases of cardiac arrest.
The potential long-term effects, however, are just as worrying.
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