Not much is truly known about the MtF gas, only misconceptions and rumors have been spread. Because MtF cases are so rare, as only 75 people have it in the entire world, it doesn't seem to be a large concern. Thus, not much effort has been put into cures or studies, and no government precautions have been taken, although society is being cautious about going outside and everyone on Earth is working together to detoxify the air.

Hidden MtF information

Transformation

When an exposed man has inhaled too much MtF, they begin the transformation into a female over a short period of 10 minutes. The gradual 20-minute body transformation into their eventual final form is called a "trance." In short, a man's sexual reproductive organs mold into a woman's during the trance, his appearance changes to appear as an attractive young woman, and his libido rises to the extreme. Strangely, not all biological males are affected. Transgender women and biological females are immune, and the change in transgender males is minimal. If body modifications were made already, the transformation will be exclusively internal. MtF gas is not able to alter the gender during pregnancy. MtF gas does not change personality, although this can be affected by the uncontrollably high sex craving and female instincts. If the male has a unique body type, such as muscular or obese, the body type will not change, only the gender.

Variations

The transformation is different for everyone, and a first trance can show in a spectrum of ways. It can be overwhelmingly painful and distressing (like turning into a werewolf), or sensual and pleasant, which it's pleasant most of the time. The man might be sensitive and feel everything from the organs shifting inside the body to the flesh and fat growth to the memory of being a past man slowly fading, or be completely oblivious and ignorant to the transformation until it's done (which can lead to various reactions from witnesses.) The features can be exclusively internal (meaning only the reproductive organs and vagina change, the breasts aren't visible and there is no change to the appearance), or female features can the man look like a totally different person.

Describing the transformation in real time

Reference MtF transformation fetishes. As in gender transformation growth, the first trance is slow-paced. The body grows in short pulses, with each breath. It can pull someone up, either by the back arching, the hips getting pulled as the flesh expands, or the changing man moaning as his throat constricts. The pectorals change to breasts, which slowly rise up, the flesh expanding and inflating like an unstoppable force, and they can get big enough to rip a shirt. The breasts jiggle, they're squishy, and they seem to pulse with the man's heartbeat. The ass and the thighs grow, as the leg muscles rapidly inflate in size, they become very thick and fatty. They also jiggle and they're squishy, as the ass expands it can lift the changing man off the floor, the thighs can clap together gently. The vulva forms from the skin of the penis and testicles as they shrink into the body. The uterus and vaginal wall forms, tearing through muscle and pressing against the pelvis. It can twitch, clench, and drip precum down the thighs. The waist visibly cinches inward. The jawline melts away. The hair grows in length, straight or curly. To relieve the pressure build-up, the man may lie down on his back or assume a suggestive receiving pose, and only assuming a sex position can relieve the transformation pain.

After transformation

After the trance, the man cannot recall ever being a man, although they still realize they were a man at some point, due to their body not being used to the change at first. The memory loss is so the man's mind and body can adapt more easily. Although, balance/coordination, voice changes, awareness of new body parts and hair and organs, and female culture might not be easy to adapt to at first. Over time, the changed man will naturally begin to act like a woman.

"Relapses"

Reference FtM transformation fetish. With an addition to the vocabulary, relapses are when a changed man temporarily shifts back into a biological male, often for only a short time. As trances are activated when a man inhales too much gas, relapses can happen when the changed man experiences extreme negative emotions (terror, rage, traumatic flashback, depression, dysphoria), or inhales a dose of pure oxygen (which is rare nowadays), although the true cause of relapses are unknown. The man will go through another trance during a relapse (except they transform back into a man.) When triggered, this time each trance (into a man and back to a woman) lasting five minutes, and the complete state of being male lasting two or three minutes.