Everything seems to be answered except for number of hazardous materials teams, so I’ll take a swipe at that.
Short answer, it depends on how “big” your big city is. Pierre ND big? Providence, RI big? Boston big? New York City big?
I can speak the most about cities in the Northeast, since that’s where I live and work.
Any city less than 400,000 people or so would probably not have a dedicated hazardous materials unit. I can’t speak for cities out west or down south, I understand some of the “smaller” cities in Texas and Louisiana near the refineries have dedicated teams, but like I said, I don’t know what they do.
Most fire departments have a heavy rescue (or two). The folks assigned to that company would handle, apart from firefighting duties, motor vehicle extrications, confined space rescues, high angle rescues, trench rescues, machinery entrapment, etc. Stuff that engine and ladder firefighters wouldn’t really deal with on a regular basis (not that they don’t know how to do it, they’re just not sent to every single one like the rescue folks are). The heavy rescue also has the tools to handle those types of situations. In most departments, the crews assigned to the heavy rescue are also the hazardous materials technicians*. Of course, in many departments, the technicians are spread throughout the city, so you send a number of companies to a significant incident and the team will form itself out of a number of individuals arriving in different vehicles.
I know Boston has a hazardous materials truck, I don’t know if it staffed all the time. They also run several decontamination units, but again, I don’t know if they are staffed.
I believe New York City has two or three (possibly five) dedicated hazardous materials units, but I’m by no means an expert on FDNY’s operations.
Some areas have combined to regionalize their hazardous materials response. Statewide in Massachusetts there are a number of teams, comprised of firefighters from all over that particular part of the state. For the “big” stuff, we can call up the line and request one (or more) of these state teams, whose members will be alerted by pager or cell phone to respond. Someone will respond with a command vehicle, someone else will pick up the equipment vehicle, and the team will assemble on site. State team activation takes a bit of time, but when they come in, they’re going to take care of pretty much anything you can hit them with.
- Three accepted levels of hazardous materials responders:
Awareness - You can identifiy a problem and call for help
Operations - You can identify a product and take defensive actions (initiate command, evacuation, diking/daming/diverting, and decontamination, but nothing that requires you to get product on you). All firefighters in Massachusetts must be Operations-level trained.
Technician - You can actively work to mitigate the hazard (you can get product on you)
Clear as mud?