I worked for a major chlorine & bromine manufacturer for 10 years.
Chlorine is very nasty in all forms.
- It boils at -34°C, which means that it can literally freeze the balls off anything it touches.
- At 20°C it has a pressure of ~6 bar.
- It's a very strong oxidizing agent - things will burn in it rapidly. Really, really bad in contact with aluminium, magnesium etc.
- It's heavier than air and so collects in pits and trenches
- >5 ppm will cause irritation to windpipe and lungs
- 30-50ppm will cause severe pulmonary oedema (lungs will fill with mucous)
- 400ppm will kill you in 30 minutes
- >1000ppm will kill in 2-3 minutes
My very late grandfather was gassed with Chlorine at Ypres. His lungs were badly damaged and he died at age 38 from lung issues.
It's not a good way to go.