[doukdouk]

Well, not putting explosives in a city is not hard; not putting substances that have some industry uses and happen to be explosive (eg fertilizer) near industry is hard.

After all, it needs to be shipped, stored and used.

If there's shipping, there will be some port city not far.

And if there is industrial use, there will be workers, and some city as well to house the workers.

See:

- Halifax explosion (how hard is it to not make explosive-carrying ships go to ports?)

- AZF explosion (how hard is it to not locate factories far away from cities?)

- Texas City Refinery explosion (how hard is it to not let refinery workers inside the refinery?)

- Tianjin explosions (how hard is it to not locate a port city near its port?)

And so forth