Air pollution in US from wildfire smoke is worst in recent recorded history

Exclusive: rapid analysis of extreme event by Stanford University shows worst day of exposure to such pollution since 2006

The US experienced its worst toxic air pollution from wildfire smoke in its recent recorded history on Wednesday, researchers have found, with people in New York exposed to levels of pollution more than five times above the national air quality standard.

The rapid analysis of the extreme event, shared with the Guardian, found that smoke billowing south from forest fires in Canada caused Americans to suffer the worst day of average exposure to such pollution since a dataset on smoky conditions started in 2006.