Second-hand smoke, no doubt.
Polonium-210
The farms around us moved to no till farming after the original families sold out. Since that time we have watched
wildlife decrease and vanish. The birds that used to be here are gone. Pheasant, grouse etc have gone. I attribute it to the weed killer spread and the hedge row nesting areas being contaminated. We leave a large portion of our land in natural state. There are still none. Kind of sad in a way.