After keeping windows open all the time, I was definitely out of the death from a carbon dioxide. When its concentration is increased in the room, the subject should die from a suffocation, but there is no proof to conclude an assassination. However, it was just effective in the closed room so that the air circulation gives us a chance to the survival.
However, that night was so cold. Hong Kong is generally warm but it becomes about 10 centidegree in the winter. Furthermore, there is no preset heating system in the room. I did not realize how cold it became as the window was always closed during the night and I slept after tired on the couch to face up with the ventilator.
The cold air still flew from the air-conditioner even in that night. It was switched off, but the Chinese intelligence blew a carbon dioxide from the upper room, which was too freezing as well. I suddenly woke up during the night feeling like I was frozen to death and my body was so cold that I immediately noticed a danger.
It was highly likely a result of the inattention and not of the well-prepared plot, but I was caught by the fear that I was going to die sooner or later. I was so pessimistic to lament my entrapment at that time, though this specific issue could be solved just to wear more clothes, which was my strategy from then on.
It was quite ironic that Hong Kong was too warm for anyone to be frozen, but it should create a huge pain if opening all the windows at the winter night. However, that was the only option I could take to counter a carbon dioxide or any other gas from the upper room.
I was in the room but realistically the same as living in the outside atmosphere, suffering from a drilling sound during the daytime and from a water pouring and beeping during the night. My all behavior was tightly watched and I was drugged quite often to lose my consciousness. I had no idea what the next additional torture was, but I tried to fight against them day by day just for my survival.