This document presents an ethical dilemma regarding pollution. It describes a society with highly polluting cars where an individual can install a device to stop their car's pollution, but it costs money. If others also use the device, the air will be cleaner even if just one person uses it. However, if others do not use it, the air will still be dirty even if one person uses it. So there is no incentive for any individual to use the device if others do not, leading to a social dilemma where no one acts and pollution increases.