The problem is not the incineration
per se but
what will be incinerated. [Some of the past and possible problems are given at:
Education - Industrial air pollution ]
For sure a lot of the hazardous substances which were burned and spread all over the neighbourhoos are now not used in industry (or not supposed to be used .... ) especially heavy metals (Cadmium, Arsenic, Lead, Mercury &c &c).
However the products or components of the vast range of plastics (which make up the majority of incinerated waste) only need to be voided in tiny quantities to be a severe chronic hazard.
Someone else may have mentioned that of course incinerators have well defined criteria for what they can accept and they wouldn't lie or be sloppy would they? However, they have to take the word of waste disposal firms who are paying their wages and (many of whom) have not the slightest regard for health and safety ..... so, I think, everyone is right to be very, very worried ....