Many bonfires are assembled for a long time before the event and in some cases unknown waste is dumped on to the bonfire. This could damage the health of bystanders and wildlife. Animals which have started to nest in the bonfire before the event can also be burnt alive, this cannot happen anymore.
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Combined, public bonfires can burn the equivalent of 1000's of trees. I believe this pollution harms human health, particularly the lungs, and negatively affects wildlife, and that the burning of certain materials, especially treated wood, plastic, and household waste, releases even more harmful toxins. The combustion of materials like pallets, especially when treated or inappropriate items are burned, generates dark smoke and soot.