Looking at the original post, I think this topic is specifically aimed at office workers in an urban setting.

Really, I think the question is what items can the average office worker put in their pockets that would help them if some sort of local disaster strikes while they are at work - be it a building fire, earthquake, terrorist attack, etc.

Given this, I think 4 is a reasonable number of items, though I don't think the question necessarily constrains answers to that. For myself, I think the constraint is more what items would be helpful yet can be carried inconspicuously and comfortably while wearing typical corporate attire.