Each year about 20,000 people are injured or killed by landmines. Victims are affected to an extent of, say, 20 life-years, for a total of about 400,000 life-years per year. Over a 10 year period, that's 4 million life-years.
Human News aims to devote 1 character to each 40,000 life-years, or 1000 average lives. Thus, this story can have about 4 million / 40,000 = 100 characters.