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Generally, manufacturing synthetic materials on this submicron length scale is a common challenge.

On the jet, they deployed lasers of different wavelengths to map a smoke column in three dimensions in real time; there was an instrument to sense acetonitrile, a chemical known to be an indicator species of biomass burning, while other sensors looked for black and brown carbon, submicron aerosol composition, and a long list of other components.

Brown was running an instrument that could detect what Coggon’s could not: submicron aerosols such as nitroaromatics.

And some of it—no one really knows yet how much—will be in the form of submicron particles that linger in the air for long periods rather than rapidly falling out.

These droplets cover a huge size range: they can be wider than 100 microns—big enough to see as they fly out—down to the submicron scale.