Fireworks aren't that bad for Montreal's air quality, new study says

The fireworks that light up Montreal's skies every summer have minimal long-term impact on the city's air quality, a new study said. 

But, the study showed that, in the minutes immediately following the shows, pollutants released by the explosives tended to drift into nearby neighbourhoods where they reach harmful levels even if their effect was localized and short-lived. 

Jean-Luc Allard, a specialist in air quality and an engineer with AtkinsRealis, the firm commissioned to conduct the study, said fireworks displays don't have a large effect on air quality in Montreal. Air quality levels remain consistently within provincial standards, he said.

The plume of smoke visible immediately after a display, however, did lead to a spike in harmful particulate matter wherever it travelled. 

"We can detect, in some cases there is a deterioration in air quality but the impact associated with a fireworks display is limited in space and time," he said. 

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Fireworks can be beautiful and exciting, but they also leave a mess of chemicals, gases and particulate matter that affect more than just short-term air quality.

Scott Weichenthal, an associate professor at McGill University in the department of epidemiology who studies air pollution, said the study did show significant spikes in air pollution in some areas of the city after fireworks displays. The affected areas change depending on where the wind carries the smoke.

"It's not like it's a blanket in the whole city and it's not lasting for for days on end," he said. "But there are definite short term increases that could have have relatively important impact on people that are sensitive."

Weichenthal said fireworks displays are a tradeoff between the economic benefit they bring and the not insignificant air pollution they cause.

Increasingly though, municipalities are reviewing their use, as residents raise concerns over noise and animal welfare. Mont-Tremblant, Que., moved to ban them last year. 

Fireworks displays drew scrutiny in the summer of 2023 when wildfire smoke blanketed Montreal. 

The smog from the wildfires caused the city's air quality to plummet and led to the cancellation of fireworks displays. While they would have been a negligible contributor to smog, according to the study, Weichenthal said conducting a fireworks display when air quality is already bad would not make a lot of sense.

Sophie Emond, the president of La Ronde, a theme park on Sainte-Hélène Island, that plays host to an international fireworks competition each year, pointed to the benefits of fireworks displays and said the study showed that some of the concerns around fireworks displays were misplaced. 

"The results of this study are clear, fireworks displays have a limited impact on air quality," she said.

"They're economic drivers, … They attract crowds, from here and tourists and stimulate the local economy. We're convinced that banning them would not be the answer to the concerns people have about them." 

They also have a very limited carbon footprint, she said. A single, medium-sized fireworks display emits about as much carbon as a bus does driving from Montreal to Trois-Rivières, Que.

People who are sensitive to air pollution and who live near a fireworks display can protect themselves, Weichenthal said, by keeping their windows closed after fireworks shows and get an air filter.