At least two Environment Canada meteorologists warned that linking Diwali fireworks to air pollution in an air quality advisory could be perceived as discriminatory, internal emails show, but the advisory was still published.

Their warnings appeared well-founded. So many complaints had poured in by the end of the day that the department reissued the advisory without mentioning Diwali and publicly apologized.

A new edict was issued that air quality warnings should make no reference to specific events.

鈥淧lease stick to meteorological explanations,鈥� reads an internal communication to meteorologists and other Environment and Climate Change Canada staff.

鈥淟essons learned,鈥� reads a response from one staff member.

Those communications, as well as hundreds of emails and other direct messages, are contained in more than 400 pages of documents obtained by The Canadian Press through an access-to-information request.

The documents show the genesis of the decision to issue the advisory in the first place, the warnings about mentioning Diwali in the days leading up to the event and the aftermath and fallout within the department.

It all began following Diwali in November 2021, when an air quality monitor picked up a small spike in air pollution in parts of the Greater Toronto Area, including Brampton and Mississauga. The increase moved the air quality index from low risk to moderate risk for about four hours.

Staff traced the spike to local fireworks set off to celebrate Diwali, a festival of lights celebrated each fall.

鈥淵ou might find this particularly interesting,鈥� one associate director at Environment Canada wrote in an email the next day. 鈥淔ireworks the cause of the spike.鈥�

It was at that time that the officials discussed monitoring Diwali and decided it would likely be wise to send out an air quality warning before the following year鈥檚 festival.

A lack of knowledge about Diwali among the staff was clear. One person wrote that based on information provided by another colleague, 鈥渢his Diwali event happens every year.鈥�

Diwali is celebrated by Hindus as well as some Sikhs, Jains and Buddhists. The date, based on a lunar calendar, usually falls between mid-October and mid-November each year.

Four days before Diwali in October 2022, discussions began anew about issuing a warning.

At least two meteorologists raised concerns, particularly about the fact warnings hadn鈥檛 been issued previously for Canada Day fireworks.

One of them suggested getting the communications department involved before proceeding. Another said targeting specific areas could be seen as 鈥渄iscriminatory,鈥� and any decision to issue a warning must be based on meteorological conditions, not just the fact Diwali was happening.

鈥淐anada Day would be a more logical place to start鈥� issuing air quality warnings linked to fireworks, he said, rather than targeting one area for one holiday.

He was shot down by one of his colleagues, who insisted based on her anecdotal experience that Canada Day fireworks don鈥檛 compare to the number and type that are set off for Diwali.

鈥淭he amount of fireworks on the night of Diwali is easily 50 times that of any other holiday I鈥檝e experienced including Canada (Day) and I鈥檓 not really exaggerating,鈥� she said.

The protocol established for the warning could be adapted for other fireworks events, but last year鈥檚 Diwali was the first time a warning was issued.

It went out the morning of Oct. 24, 2022, and the backlash was swift. By the end of the day, Environment Canada鈥檚 inquiry line had received 60 formal complaints, calling it 鈥渞acist鈥�, 鈥渟hameful鈥� and 鈥淓urocentric.鈥�

More poured in through other avenues, including via The Weather Network, which sent out the alert via its mobile app.

鈥淚 am a Hindu who recognizes Diwali as an important religious event and am concerned that this message may cause citizens who do not celebrate Diwali to target Hindus for polluting the air around them,鈥� one person wrote.

Several others questioned why such warnings were not issued on Canada Day, too.

Environment Canada staff then scrambled to respond, calling in communications experts and senior managers to help.

In addition to issuing a new advisory without mentioning Diwali or fireworks, it was decided that in the future, only meteorological conditions should be mentioned in any warnings.

One air quality expert weighed in to explain that there are meteorological reasons why fireworks in the fall 鈥� for Diwali or otherwise 鈥� would cause more air pollution than those fired up in the late spring or summer months.

Largely, that is because of what is known as a 鈥渢emperature inversion,鈥� in which the surface air is actually colder than the air above it.

That phenomenon is common in the fall, particularly after sunsets, which occur much earlier in October than they do in July. That phenomenon also tends to trap air pollution lower to the ground, causing the spike in air quality readings.

While many staff involved in the fallout appeared to agree that the warning mentioning Diwali should not have been issued, others defended the plan.

Several pointed out that the air quality did spike that day in Brampton, rising exponentially to 25 times the normal level by midnight, and five times the previous record that had been set in 2013. It returned to low risk levels by about 3 p.m. the following day.

鈥淚n this world of political correctness in which we live鈥�.I wanted to draw your attention to the numbers from last night,鈥� one staff member wrote. 鈥淥ff the charts!鈥�

In an internal communication about that spike written on Oct. 25 last year, Environment Canada said meteorological conditions had created 鈥渁 perfect setup鈥� for the fireworks to cause a spike in air pollution, with a 鈥渧ery strong inversion and light winds.鈥�

Still, some staff suggested pushing back against criticism by collecting data on the number of people hospitalized as a result of the air quality issue. And at least one person said that at the end of the day, holiday or not, their job was to monitor for air pollution and warn the public when it鈥檚 bad.

This report by The Canadian Press was first published Oct. 2, 2023.

Mia Rabson, The Canadian Press