The reason for this lies in the buildings themselves. These large buildings usually have windows that cannot be opeened.The same air stays in the building for a long time and becomes unhealthy.It may be full of chemicals that come from the furniture , the rugs , or thephotocopy machines.Or it may be full of cigarette smok.This unhealthy air causes "sick building syndrome," as doctors call this problem.In order to cure the people with this syndrome , it is necessary to treat to treat the building.The answer is simple : more fresh air.