Deadzones should be separated into two different categories: Biohazard and Radioactive instead of the one in 3.x that is “both” and doesn’t make much sense.
TL:WNR: Biohazard deadzones require respirators and deal immediate damage, Radioactive deadzones give you radiation poisoning
Biohazard
Biohazard Deadzones are zones in which a form or respirator is required to not get affected. Biohazard Deadzones deal slow damage but rapidly decrease the immunity bar.
Certain items could help protect against it with various degrees of effectiveness: Balaclavas, Bandanas and Sickness/Dust Masks give low protection, Construction Respirators give medium protection, while Gas Masks, HazMat hoods and the Snorkel+Oxygen Tank (if the oxygen is still transmitted by WiFi like in 3.x) will provide full protection.
These deadzones can be found in labs, certain parts of hospitals and in places where there has been an ecological disaster (e.g. a lake where some toxic materials have been dumped unwillingly because of the infection).
Radioactive
Radioactive Deadzones, as the name suggests, are radioactive. Radiation is a silent killer, unless finding a Geiger counter, or dweling far enough into the “Zone” to see the radiation having effects on your vision. Entering radioactive deadzones will give the player different levels of radiation poisoning depending on the amount of exposure time and how close the player was to the radioactive source. Radiation poisoning itself doesn’t deal any damage, but affects almost all other stats: it will gradually reduce your immunity, and will double the consumption rate of food, water and stamina. Radiation poisoning will always linger, and can only be cured by taking Anti-Radiation pills, but all they will do is stop radiation poisoning and not heal any damage done by it.
You can advance through radioactive deadzones only by using a Lead-Lined Scientific Radiation Suit, only found in Scorpion-7 or near nuclear power plants.
These Deadzones will appear in certain areas, such as any radiological disaster (such as in Russia) and near The Washing Machine.