How much worse is burning this stuff than a vinyl siding apartment complex fire? Back of the envelope they burned about 2 orders of magnitude more material tha

How much worse is burning this stuff than a vinyl siding apartment complex fire? Back of the envelope they burned about 2 orders of magnitude more material than in a large one of those, but were maybe in a 2 orders of magnitude less dense population area than those often take place in. Does the vinyl chloride precursor burn into much worse stuff than the polyvinyl version, for equal masses? I get that it might cross some threshold for acute effects for people right near by that the other fires may never cause even for direct neighbors.