The plural of fireman is firemen. If you want to use inclusive language, then you can say firefighter and firefighters.
Cambria
The personal pronoun that takes the place of the plural noun 'firefighters' is they as a subject and them as an object.example: The firefighters use this facility for training. When they damage it, a local contractor repairs it for them at no charge.
The release of a large amount of radiation, the death of about 50 firefighters and plant staff, the evacuation of the neighbouring town and area.
They don't have to be beige/khaki. Many departments use black, and some even use red!
firefighters use water because when water touches something it cools down
water is the most practical thing to use
Thermal infrared cameras are used for many things. Examples of this are with firefighters. Firefighters use these cameras to see through smoke and possibly through walls. Also, police officers may use these cameras to seek out running criminals in the dark. People interested in the supernatural may additionally use thermal infrared cameras as it can help to see paranormal apparitions.
There is no standard collective noun for firefighters, in which case a noun that suits the situation can be used; for example a crew of firefighters, a squadron of firefighters, a team of firefighters, etc.
It's Carbon Dioxide (CO2)
The possessive form for the plural noun firefighters is firefighters'.
they use oxygen mask to breath so they die in all the smoke