That leaves 820 liters of air, one-fifth of which (164 liters) is oxygen. If a trapped person consumes 0.5 liters of oxygen per minute, it would take almost 5 and a half hours before all the oxygen in the coffin was consumed. “There's nothing someone [buried alive] could do.
Subsequently, one may also ask, why was Joan of Arc put to death?
According to historians, Joan of Arc was 19 when she was burnt at the stake in Rouen by the English on 30 May, 1431. She died of smoke inhalation. The Cardinal of Winchester is recorded as having ordered her to be burnt a second time.
What was Joan of Arc accused of when she was captured?
Joan of Arc, a devout saint of God, was burned at the stake in May of 1431 on charges of heresy. After a long trial that lasted over a year, three major indictments were made against her. The first of these was that she used magic because she claimed to hear voices from St. Michael, St. Margaret, and St. Catherine.