Sunday evening's commute at Union Station was anything but ordinary for one Toronto resident who reported feeling a "burning sensation" in their mouth followed by lots of coughing after travelling through the area, leading to lots of conspiracies about the source of the symptoms. 

The commuter took to Reddit shortly after the incident to ask other users if anyone else experienced the same sensation at Union Station around 5:30 p.m. 

"I just left Union Station, I was making my way to the Lakeshore West train and my self and my buddy felt a burning sensation in my mouth and me and my buddy started coughing," the thread reads. 

"Then others started coughing and within 30 seconds around 20 people were coughing or covering their mouth and trying to get out of the area and more talking about it or looking around. I didn't stick around to find out what was going on. I still feel kind of light headed. Just wondering what the hell happened." 

Anyone feel a burning sensation and coughing at union station around 5:30?
byu/Huntguy inaskTO

The thread has already amassed over 100 comments in less than 24 hours, with lots of users speculating about the source of the symptoms. 

"I was waiting to see what platform to go to and all of a sudden I see everyone running out coughing," one person wrote. 

"Some girls said their lips and faces were burning this transit guy gave them wipes and called for officers to come I don't know still what happened when I ran to the go train nobody knew. I'm dying to know what that was about. I definitely felt dizzy and I'm still coughing and have a headache." 

Another person suggested that someone in the station could have possibly been pepper sprayed. 

"Sounds like pepper spray. Someone did that I my high school and exactly what you described. Can't imagine it's anything else. If so, wouldn't worry about any long term effects," they said. 

Just before 6 p.m. on Sunday, Toronto Fire Services tweeted that crews were on scene at Union Station for a "CBRN [Chemical, Biological, Radiological and Nuclear] Level 2 Incident," with no reported injuries at the time. 

In an update at approximately 7:30 p.m., Toronto Fire wrote that they had ruled out "any cause for concern" after an investigation, although the source of the incident was not confirmed. 

"Could have been some concentrated cleaning solution or base chemicals that spilled. Your coughing symptoms sound like a mild case of vapour exposure, whatever it was," one Reddit user concluded.  

"Another commenter said it was a CBRN Level 2 incident, which is about mid-level on that hazard scale. In any case, breathe lots of fresh air and rinse your throat out before drinking lots of water for a few hours." 

At the time of publication, Toronto Fire has still not confirmed what the source of the incident was.