I don't know why. Perhaps because I never heard of hazardous substance days at firehouses elsewhere. Perhaps because it sounds less as if I made up the story.

Not necessarily a day, but I know that it's not uncommon for fire departments to do similar things for testing items for lead.

Is test-your-stuff day common where you are from?

https://en.wikipedia.org/wiki/List_of_highest-income_countie...