Radiation effects begin with debuffs. The “Irradiated [x]” parts listed in the following are what will show up in the status window at that level of irradiation. Subtract one from it, then multiply it by 10 to arrive at your approximate current level of radiation.
Irradiated [6] (50 Rads) = Speed -1.
Irradiated [9] (80 Rads) = Speed -1, STR -1.
Irradiated [11] (100 Rads) = Speed -2, STR -1, INT -1
Irradiated [13] (120 Rads) = Speed -2, STR -1, INT -1, DEX -1
Irradiated [14] (130 Rads) = Speed -2, STR -1, INT -1, DEX -1, PER -1
Irradiated [16] (150 Rads) = Speed -3, STR -1 ,INT -1, DEX -1, PER -1
Irradiated [17] (160 Rads) = Speed -3, STR -2, INT -1, DEX -1, PER -1
Irradiated [21] (200 Rads) = Speed -4, STR -2, INT -2, DEX -1, PER -1
Irradiated [24] (230 Rads) = Speed -4, STR -2, INT -2, DEX -2, PER -1
Irradiated [25] (240 Rads) = Speed -4, STR -3, INT -2, DEX -2, PER -1
Irradiated [26] (250 Rads) = Speed -5, STR -3, INT -2, DEX -2, PER -2
Irradiated [31] (300 Rads) = Speed -6, STR -3, INT -3, DEX -2, PER -2
Irradiated [33] (320 Rads) = Speed -6, STR -4, INT -3, DEX -2, PER -2
Irradiated [35] (340 Rads) = Speed -6, STR -4, INT -3, DEX -3, PER -2
Irradiated [36] (350 Rads) = Speed -7, STR -4, INT -3, DEX -3, PER -2
Irradiated [38] (370 Rads) = Speed -7, STR -4, INT -3, DEX -3, PER -3
Irradiated [41] (400 Rads) = Speed -8, STR -5, INT -4, DEX -3, PER -3
Irradiated [46] (450 Rads) = Speed -9, STR -5, INT -4, DEX -4, PER -3
Irradiated [49] (480 Rads) = Speed -9, STR -6, INT -4, DEX -4, PER -3
Irradiated [50] (490 Rads) = Speed -9, STR -6, INT -4, DEX -4, PER -4
Irradiated [51] (500 Rads) = Speed -10, STR -6, INT -5, DEX -4, PER -4
Irradiated [56] (550 Rads) = Speed -11, STR -6, INT -5, DEX -4, PER -4
Irradiated [57] (560 Rads) = Speed -11, STR -7, INT -5, DEX -5, PER -4
Irradiated [61] (600 Rads) = Speed -12, STR -7, INT -6, DEX -5, PER -4
Irradiated [62] (610 Rads) = Speed -12, STR -7, INT -6, DEX -5, PER -5
Irradiated [65] (640 Rads) = Speed -12, STR -8, INT -6, DEX -5, PER -5
Irradiated [66] (650 Rads) = Speed -13, STR -8, INT -6, DEX -5, PER -5
Irradiated [68] (670 Rads) = Speed -13, STR -8, INT -6, DEX -6, PER -5
Irradiated [71] (700 Rads) = Speed -14, STR -8, INT -7, DEX -6, PER -5
Irradiated [72] (710 Rads) = Speed -14, STR -9, INT -7, DEX -6, PER -5
Irradiated [74] (730 Rads) = Speed -14, STR -9, INT -7, DEX -6, PER -6
Irradiated [76] (750 Rads) = Speed -15, STR -9, INT -7, DEX -6, PER -6
Irradiated [79] (780 Rads) = Speed -15, STR -9, INT -7, DEX -7, PER -6
Irradiated [81] (800 Rads) = Speed -16, STR -10, INT -8, DEX -7, PER -6
Irradiated [86] (850 Rads) = Speed -17, STR -10, INT -8, DEX -7, PER -7
Irradiated [89] (880 Rads) = Speed -17, STR -11, INT -8, DEX -7, PER -7
Irradiated [90] (890 Rads) = Speed -17, STR -11, INT -8, DEX -8, PER -7
Irradiated [91] (900 Rads) = Speed -18, STR -11, INT -9, DEX -8, PER -7
Irradiated [96] (950 Rads) = Speed -19, STR -11, INT -9, DEX -8, PER -7
Irradiated [97] (960 Rads) = Speed -19, STR -12, INT -9, DEX -8, PER -7
Irradiated [98] (970 Rads) = Speed -19, STR -12, INT -9, DEX -8, PER -8
Irradiated [101] (1000 Rads) = Speed -20, STR -12, INT -10, DEX -9, PER -8
I’m not mathematically inclined enough to derive a pattern from this, but I’m sure someone is. The radiation debuff caps at “Irradiated [1996]” with ~19950 rads, and does -399 Speed, -249 STR, -179 DEX, -165 PER, and -199 INT. You can get more irradiated, and the number in the status window will continue to climb, up to “Irradiated [2000]” at ~19990-20000 rads, but it does not show any stat changes beyond Irradiated [1996].
Radiation seems to be quite bad for your health. I’ve seen 100 rads reduce healthy (not healthy_mod) from 0 to -55 in only four hours game time. It’s possible that it might directly harm health without having to go through healthy_mod, but I have not confirmed this.
~150+ Rads, mutations can manifest, if enabled in Settings. I’ve never seen them below that count, but that doesn’t mean they can’t occur below it.
~160+ Rads, nausea begins to manifest. Once again, I’ve never seen it at lower levels, but I don’t make a point of standing in nuclear waste for science, so don’t quote me on that.
~250+ Rads brings possible pain and HP damage. In my experience, higher levels of radiation than this don’t really increase the damage incurred per instance, but may increase the likelihood of occurrence.
Higher levels of radiation don’t appear to bring anything else new, but may increase the likelihood of each of these happening. Take note that radiation tanks your health, so high levels of it will greatly increase your odds of getting sick without environmental protection for the mouth.
As far as I can tell, boomers and huge boomers can only blind you and break windows if they explode adjacent to them; I’ve not seen any evidence of radiation from them, but I wouldn’t discount the possibility, given that the huge ones glow. Huge boomers glow in the dark themselves, making them easy targets for hunting at night, and their bile does too. As sanyaskillpro said, if they spit on you, you will glow in the dark, making you visible to zeds in the area if you’re around at night.
Smokers seem to be much the same. I recall reading once in the original thread for PK’s Rebalancing that Smokers once had ambient radiation, but the developer for the mod removed that and replaced it with an attack that gave radiation.
Bloated zeds leave behind radiation. When they explode, the gas cloud leaves behind ambient radiation. Ambient radiation settles into the tiles it occurs on and never leaves, unless that has changed since I last played.