The word ‘person’ is rarely pluralized with an s. However, there are cases in English where it is sometimes possible. You can find examples of this on elevators, subway trains, and signs that state the legally permitted number of people who are allowed in a specific space. The reason for this is that extra emphasis is put on each and every person in that space as it serves as a warning for non-compliance. In the above case, 16 persons are allowed on the elevator. If one extra person comes on the elevator, it may fall. It would be impossible to convey this idea by using the more commonly used plural ‘people’. (irregular plural)
