First post. On any forum ever. I usually actively avoid fora, but something from this "What if?" was bugging me. The post wraps up by stating that if all the pollen in the air were gathered into one pile and set alight, then the resulting explosion. . . But doesn't the act of gathering the pollen into a pile negate the whole surface area thing? I'm thinking of the lycopodeum powder experiment from high school chem (lycopodeum powder is a mold spore, not a pollen, but the principle applies; the same goes for the iron, milk etc. used as an example in the post). Lycopodeum powder won't burn in a pile in your hand but will when dispersed in the air. Same for pollen, no?
Definitely. The key is that oxygen should be able to reach the fuel at a rate quick enough to sustain the reaction.
One of the fun experiments I did in university (I studied chemistry) was to make pyrophoric iron. It is basically a very elaborate process to make iron into a very fine powder. At the end of the experiment, the powder just sits there, until you pour it down from your test tube into a receptacle, which causes the fine iron powder to ignite spontaneously. Looks very cool, but it is 2 days work in the lab for a few seconds of fun. (look it up on Youtube)