Are these harmful particles aluminum-specific or general to all metals? What if it was carbon fiber, titanium, thin sheet steel, or some nontoxic plastic? Wood

Are these harmful particles aluminum-specific or general to all metals? What if it was carbon fiber, titanium, thin sheet steel, or some nontoxic plastic? Wood is a really odd choice, as it is not a very uniform and predictable material to work with, and it seems "reduce detrimental effects on the ozone layer" is the real constraint, rather than biodegradability. For things on land that decompose rather than burn up, it may be true that "reduce toxic effects on soil and the ecosystem" == "biodegradability", but it's not obvious to me that this applies to something burning up in the atmosphere. Burning wood isn't particularly great for the ozone layer either (c.f. forest fires).