Three smoke "blasts". A couple of sprays of grey primer, followed by a couple of pure white.
Three explosion "blasts". A couple of sprays of black primer, followed by a light spray of grey.
One poison gas "blast". Spray as smoke the hightlight with some green.
This pic might show the green-ish hue of the smoke a bit better. Simply a quick drybrush with Foundry Phlegm Green light.
These are the armatures on to which I stick the Woodland Scenics foam, using smelly all purpose glue from (UK) Bostik or Uhu. MDF bases with holes drilled for kebab or cocktail sticks.
A trick to help make them slight more durable is to prime the foam with very thin PVA before spraying. Make sure you allow plenty of drying time tho. Thanks for looking!