ABSTRACT
Most people understand that there is a small but nite risk of being killed by a falling airplane. While most people do not view this as a signi cant risk, they are surprised to learn that the risk of being killed by a crashing aircraft is four times the threshold risk (one chance in a million) that the US Environmental Protection Agency (EPA) uses in evaluating standards for regulating toxins.1 Even more surprising is how few people realize the risk of a fatality due to a large comet or asteroid impact.
