Washington DC and Philadelphia experienced their worst air quality in years as intense wildfires in Canada continue to impact millions. The poor conditions have forced event cancellations and grounded flights across the US. Nearly 100 million people are experiencing very poor air quality in North America. US President Joe Biden described the fires as a “stark reminder of the impacts of climate change”. …Cities including Washington DC, Philadelphia and New York had significantly worse air quality than cities abroad such as Lahore, Dhaka and Hanoi. The smoke has caused the cancellation of school outings and sporting events, and, in the capitol, the White House’s planned pride celebrations. The National Zoo was also closed, with its animals, including three giant pandas, taken indoors to shelter. …Mr Biden said he spoke to Canadian Prime Minister Justin Trudeau on Thursday and deployed more than 600 firefighters to help battle the blazes in Canada.