One out of every ten to twenty people will experience a nosebleed each year. Most are resolved with minor first aid treatment. Still, almost anyone experiencing a sudden and unexplained nosebleed (the medical term is epistaxis) wants to find out what caused it. If it happens at work, they'll often question if workplace factors are the cause.
What to do? First, basic first aid treatment calls for keeping the person with a nosebleed calm. Have them sit upright, lean slightly forward, and pinch the nostrils for five or ten minutes. Don't allow the person to clear their nose by blowing or removing clots. Applying ice (crushed in a plastic bag or washcloth) to the nose and cheeks may help stop the bleeding. Seek medical help if the nose continues to bleed after 10-15 minutes, if the bleeding is severe, or if the nosebleed is recurrent.