The BioCrisis refers to a widespread environmental crisis beginning prior to the events of Oni. At the time of Oni, the air supply in the cities is systematically filtered and decontaminated by ACCs. We learn from Dr. Hasegawa's diary that massive contaminated areas called "Wilderness Preserves" exist outside the cities. One such contaminated zone is the reason for the death of Jamie Hasegawa. Drs. Hasegawa and Kerr subsequently developed the Daodan project to help humans survive an impending danger from the BioCrisis. The BioCrisis is still an ongoing event and a current threat. The WCG assures the general populace that they have it under control, but in-game posters (right) indicate that civilians are still expected to wear masks in the cities despite the use of ACCs to process the air.
The following console quotes shed only a little light on the nature of the BioCrisis:
The new systems modifications are designed to combat the steady rise in Class 3 atmospheric pollutants but the new parts have not been tested at full capacity. The second tier test will be followed by a test of the third tier, assuming everything goes according to plan.
ATMOSPHERIC INVERSION PROCESS TESTING
As a result the Class 3 toxins we are most concerned about would pass through the system untreated. There is even a chance that the they would be charged as they passed through the coupler transforming them into Class 4 airborne toxins.
ATMOSPHERIC INVERSION PROCESS TESTING [cont]
Needless to say the environmental damage in such an event would be catastrophic and irreversible. All crews must be aware of this danger and pay strict attention to the posted maintenance schedules and testing protocols.
All that we can glean from these consoles is that the pollutants are called "toxins", they are "airborne" (hence the Atmospheric Conversion Centers), and that there is a "steady rise" occurring in class 3 toxins. That last fact is the most significant.
There is one other console that mentions the nature of the pollution:
<<<Secondary Stage: COMPLETE>>>
STURMANDERUNG baseline report: Dioxin levels
Project initialization: 97 ppm
Primary stage: 100 ppm
Secondary stage: 152 ppm
The mention of dioxin, a cancer-causing chemical compound, seems to be merely a side effect of Muro's plan, the main purpose apparently being to trigger the inversion process mentioned above, wherein the class 3 toxins pass through the system untreated or are even elevated to class 4.
What exactly is the nature of the contamination of the outside world? Are all areas equally polluted? How did the BioCrisis come about in the first place? These questions are not specifically answered in Oni, but we can extrapolate from what we know.
To tackle the last question first, the pollution which the ACCs were developed to combat might simply be the result of mankind's current habit of polluting Earth. One could postulate that if some of our current habitual pollution is making things worse than we think, it might be too late to reverse the damage when it's finally noticed. This is one possible explanation for the BioCrisis. The other explanation is that there was a specific event such as nuclear or biological warfare, or a massive chemical reaction, that caused the Crisis.
It's also possible that concentrated waste produced during the ACCs' decontamination process is being improperly disposed of, making the problem worse by creating highly contaminated soil ("a poisonous world") wherever that waste was dumped. (For what it's worth, Hasegawa's description of a typical Wilderness Preserve is reminiscent of Miyazaki's Nausicaa.)
Once the ACCs were built in some cities, people would have huddled together in those locations. Hasegawa's diary makes it clear that ACCs did not cover the entire inhabited earth ("The world outside the Atmospheric Processors is poisonous"). Some areas are apparently worse than others; when he and Jamie explore a Wilderness Preserve, he calls it "one of the Contaminated Zones, the dirty secrets that the government made it easy to ignore." Apparently not only is it dangerous to live outside of the ACCs' area of effect, but there are specific zones that are much worse than people realize.
We also get the impression that the WCG is rather complacent about cleansing the area outside the cities. Supposedly a BioCrisis Subcommittee was dedicated to monitoring the status of the pollution and augmenting the efficiency of the ACCs. Perhaps they have been telling people that they are doing so when in fact the situation is unmanageable. The required cleanup work might be too costly for anyone to perform, even a world government; the reason might be more sinister, too, such as the fact that it is easier to monitor and control a population when they bunch up in cities than when they are spread throughout the countryside. We also don't know if the cause of the pollution is ongoing (see below).
It's interesting to note that, as far as people know, their lives within the cities are sustainable. As long as the ACCs keep pumping out clean air, everything will be fine. After losing Jamie to a Contaminated Zone, Hasegawa feels differently: "If something isn't done we are all doomed."
The entry that we hear from his diary is unfortunately not clear on why humanity is doomed. Did Dr. Hasegawa observe the "steady rise in class 3 pollutants"? Did he predict that the hostile environment of the Wilderness Preserves would overtake the cities at some point? Perhaps the ACCs are not keeping up with the growing pollution.
We still have not addressed the first question this section raised: the nature of the pollution. There are three possibilities:
- Toxins which have saturated the biosphere, to the extent that a plant can kill someone with a mere scrape from its thorns.
- Advanced biological agents such as powerful viruses — perhaps mutated by the original pollution.
- Alien life invading and reshaping our ecosystem.
If #1 is the case, then something must be continuing to pollute the earth. Poisons do not multiply themselves; as long as runoff from polluted soil and toxic rain are not allowed to enter the city, then the environment in those cities should be sustainable. Is there an ongoing industrial or organic process that is producing more pollutants?
Perhaps #2 is the case, and the WCG is using the word "toxin" to avoid the panic that would arise if people were aware of the active nature of the threat. Living, virulent organisms might be in the process of spreading and invading the cities, rather than inert toxins. They could be mutated viruses created by the initial man-made pollution.
Option #3 may seem much more far-fetched, but there is a mention of extraterrestrial life in the description of the Screaming Cell Cannon. Where are the Screaming Cells coming from? Is it possible they are are being harvested from the Contaminated Zones? The infection that kills Jamie could well be some life form that is not of this earth. Any further conclusions cannot be reached from the facts that Oni gives us, leaving the rest to our imaginations to fill in. See Oni2:Slaves of War for a fan theory based on this option.