Say hello to my little friend, The Tick From Millbrook.
When wearing Level A protection, it is not uncommon for the environment inside the suit to be 20-30 F. hotter than ambient, and 100% humidity, within minutes of sealing up the suit. Because of this, medical monitoring is required before and after working in these suits.
Hazmat gear will usually be worn in several layers, making it even less comfortable to wear. Hazmat gear consists of an air- and water-proof oversuit, booties, gloves, and a hood. These pieces are often taped up, at the ankle and wrist, so that there are no gaps for nasty things to enter. After using this equipment in a hazardous environment, firefighters will have to be decontaminated (washed off) before they can remove the protective clothing.
The first layer is often station wear (uniform) or a one-piece Nomex jumpsuit. The jumpsuit seals snuggly at the ankles, wrists, and neck, giving fire protection - otherwise, in the event of a flash fire, the plastic suit otherwise stick to the skin. The back of the jumpsuit has a large patch identifying the wearer.
When I get to the climb I'll take off the HMS and put my clothing on.