The reason for this lies in the buildings themselves. These large buildings usually have windows that cannot be opened. 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 the photocopy 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.