You need to lump people into higher and higher level "intersections" (district, city center, region, state, continent, planet) along with other identifying data

You need to lump people into higher and higher level "intersections" (district, city center, region, state, continent, planet) along with other identifying data, until at least "k" people are in each group and can not be told apart: https://en.wikipedia.org/wiki/K-anonymity https://en.wikipedia.org/wiki/K-anonymity