The ventilation is most likey the problem but without actually seeing you place it is difficult to commnet. Have a look at what i’ve writen above. 🙂

The ventilation or lack of is most frequently the root cause. In modern open plan offices there are usually too many people and the system has not been designed for such a hihg occupancy. A common cause is alsoa complete lack of fresh air supply. A common miscnception is that the air conditioning system provides fresh air. this is hovewer rarely the case. Most frequently the air con just conditions the existing air (warming or cooling it) and does not remove contamiants. So if your office has one of these that all the bacteria and comon visuses remain in the atmosphere and are past between people causing inlnesses. Solutions are relativelly simple but difficult to introduce due to cost inplications.