People who work in large office building get sick more than normal.They may have headache,or sore,red skin. They 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 become unhealthy.it may be full of chemical that come from the furniture,the rugs,or the photocopy machine.or it may be full of cigarettes smoke.this unhealthy air causes "sick building syndrome".as doctor call this problem.in order to cure the people with this syndrome,it is necessary to treat the building.the answers is simple :more fresh air