Thanks all, I did in the end decide to put the onion skins down waste disposal, there isn't usualy much for the comost heap, cat, dogs, hens, geese, goats get first pick, not much left after that
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When you realise what crud is in the air 24/7 putting any veg or fruit peelings in the compost heap is minuscule.
Good point, I like to think where we live, fairly high above local towns etc, is relatively clear, but as someone pointed out we are SE of Sellafield (is it still called that?), anyway when I do go down into town, as little as possible, I can smell the fumes, or in the car I'm always closing the vent off because I can smell fumes from vehicle in front, I like my high hillside home :-)
As to roots I worked out a few years ago dunking perrenial weeds is the way to go, don't see it recommended on programmes, a friend takes her nettle roots etc down to the tip, says I'm just making work for myself, I'll work that one out one day