Officials report that there have been 3 deaths in Japan involving dry ice in coffins over a period of two years from 2020 to 2021.
They also say there have been cases of people found lying unconscious next to a coffin, or losing consciousness with their face in the viewing window of a casket.
In the wake of the accidents, the National Consumer Affairs Center of Japan conducted an experiment to measure the concentration of CO2 by putting 10 kilograms of dry ice in a coffin. The concentration rose sharply when the coffin lid was closed. After 20 minutes it exceeded 30 percent, which is enough for someone to immediately lose consciousness. After four hours it rose to around 90 percent.
The CO2 concentration dropped after the lid was opened, but remained at more than 30 percent after 50 minutes.
The agency recommends sufficient ventilation, and that mourners not be alone in case of an emergency, and to step away from a coffin if they feel ill.