An individual flying over the chernobyl site two days after the explosion most probably experienced what hazard or hazards?

Acute exposure to radioactive substances.

Acute exposure is radiation exposure that occurs in a short time period. It can be an exposure that occurs once in your lifetime. This might be that one foot x ray you had because you may have broken your foot. Acute exposure can also be exposures that occur more than once, but very infrequently and for short periods of time. This might be dental x rays you get every few years.