A visual guide to the Canada wildfires and US smoke pollution

Where are the fires and why are they so bad?

There are more than 400 wildfires burning across Canada, with many out of control, according to officials. The fires are unusual in their timing, size and location. The “fire season”, when weather conditions are ripe for conflagrations, has only just begun. A third of the fires are in the boreal forest in the eastern province of Quebec, a place not used to dealing with large blazes.

Fires are now burning in every Canadian province except for Prince Edward Island and Nunavut, a frigid northern region where trees cannot survive. The amount of land consumed is also striking – more than 4.4m hectares has burned so far this year (2.7m since the start of the fire season).

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Why did the sky above New York turn orange?

The city’s sky turned from milky white to a dystopian tangerine on Wednesday, bringing with it a smell similar to a campfire.

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The hazy skies were caused by plumes of smoke from the Canadian fires when winds funnelled the haze first to Ottawa and Toronto and then directly into many of the major population centers of the US east coast.

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What is causing this?

Forest fires are not new for Canada but, much like in other places such as California, scientists have found fire seasons are getting longer and more intense due to the climate crisis.

Analysis of a procession of huge fires in British Columbia in 2017 found they were driven by extreme warm conditions made up to 11 times worse by climate change. No attribution study has been done on the current fires, although scientists will probably be undertaking work on these, including a blaze that was the largest in Nova Scotia’s history when it erupted in May.

Extra heat and altered rainfall patterns are causing a long-term change in fire behavior.

What has been the impact of all this smoke?

Unhealthy air warnings at one point covered 110 million Americans, not just in New York but also cities including Philadelphia, Washington DC and Boston. Footage from space taken on 7 June shows Canada wildfires smoke reaching Pennsylvania.

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In New York, where schools and playgrounds shut down and outdoor activities were restricted, people started donning masks outside not worn since the early days of the pandemic.

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Health experts said they expected an uptick in hospitalizations due to respiratory and cardiovascular problems triggered by the foul air, which in New York was the worst of any major city in the world.

Levels of PM2.5, tiny particles of soot, dust and other burned debris found in smoke, were five times above “safe” national air quality guidelines, posing significant dangers for the lungs of people with health complications, pregnant women, children, the elderly and other vulnerable groups.

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What happens now?

The crisis has somewhat abated for New York and Philadelphia on Friday, with blue skies starting to peep out from behind the haze, although the smoke’s southward path caused Washington to issue an alert, its first ever, over hazardous air quality conditions.

And the fires are still burning, with US environmental agencies providing smoke forecasts for the coming days with advice for citizens on what activities to avoid.

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