The Windsor Professional Firefighters Association says it will document any incidents of "delayed response times" once city council's new plan for the department is implemented.
Council approved the closure of three fire stations and the construction of two new ones.
Angelo Gertsakis, president of the union, calls the plan "dangerous and outdated" for fire service.
"We're telling the general public that the service that we have in this city is not adequate enough for the citizens, and they deserve better. We're going to fight to get them the better service," Gertsakis said. "if we have to go knock on everybody's door and make them aware of what the city is trying to do, we will do that."
The union wants the city to withdraw the current proposal, which has been approved by council, and conduct "a proper public consultation" of the plan's impact on public safety.
"We're just going to do our studies," Gertsakis said. "The Windsor firefighters aren't just going to stand back and watch it go without a fight."