These were paved state/federal highways, not dirt roads. I just asked because whenever they oiled/sanded the road it must have been quite a while before since there was no evidence of anything having been spread recently...just looked like any other paved road. Maybe no one ever got around to taking down the signs.
I figured it had to be something to freshen/prolong the life of the asphalt, but it's not something I've ever seen done around here.
Calcium chloride is what I remember being used when I was growing up, sometimes they'd just spray water. I think they might have used river water, because sometimes it smelled really swampy.
Don't ever remember seeing oil used on roads, though some farmers would pour used motor oil along fence lines to keep the weeds down. I guess nobody really thought about how bad it was. I was guilty of that too when I still lived in an apartment...I'd go to some gravel pit or someplace similar and just let the oil drain on the ground when I'd do an oil change in my car. :embarrassed: Hopefully, the statute of limitations is up.
I can only imagine what's getting in the air even now from people who use waste oil furnaces to heat shops, etc.