MercoPress. South Atlantic News Agency

Fearing forest fires and bad air quality, Canada cancels fireworks display.

On Friday, cities including New York, Toronto, Montreal and Washington DC were near the top of a list of major cities with world's worst air quality.

Persistently bad air quality over North America and worries about sparking more fires has led to the cancellation of some Canada Day firework displays. There were also concerns over air quality around next week's Fourth of July celebrations in the US.

Smoke has drifted over large sections of the US and Canada this week.

On Friday, cities including New York, Toronto, Montreal and Washington DC were near the top of a list of major cities with world's worst air quality.

The first night of an annual fireworks competition in Montreal on Thursday was called off, and the city's Canada Day display, set for Saturday night, has also been cancelled.

However a celebration in Toronto is still scheduled to go ahead. The city was continuing to monitor the situation, a spokesperson said, but no changes were planned as of late on Friday.

The 1 July holiday commemorates the British North America Act, which merged four British colonies into a single new country in 1867. Like the Independence Day holiday in the US, it is traditionally marked with outdoor events, including fireworks.

A number of cities and towns in some of the worst affected areas cancelled their Canada Day pyrotechnics or moved them away from wooded areas.

Officials are not only worried about the explosives making bad air quality worse, but also potentially setting off further fires during what has already been declared Canada's worst wildfires season since records began.