[sitharus]

If the incineration happens at over 1000°C and the facility has operation exhaust gas scrubbers then not much. You'll end up with bromine, chlorine and fluorine salts in the ash.

If it's below 400° (as happens if you burn plastic in your backyard or fireplace) you'll release dioxins, which are persistent fat-accumulating toxins, and fluorine and bromide compounds which are typically bad news to anyone downwind.

It does depend on the plastic you burn though. Some are worse than others, but 1000°+ controlled incineration is typically fine for all.

[beachy]

We watched a documentary on people living with minimal waste, which highlight an elderly couple who managed to live with less than one rubbish sack of waste per year.

I was admiring their efforts until I noticed a smouldering rubbish heap in their back garden. Sure enough, they burned all their plastic and other waste.

[90minuteAPI]

I don't think that really counts as living with minimal waste then.