The concentration of a chemical in the air that is released by people when stressed is an objective indicator for setting the age rating of films, finds a new study. The more nervous moviegoers are, the more isoprene they emit - a measurable indication of how stressful a film is.

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The concentration of a chemical in the air that is released by people when stressed is an objective indicator for setting the age rating of films, finds a new study. The more nervous moviegoers are, the more isoprene they emit - a measurable indication of how stressful a film is.