It's not a grainy, gray street dust.

它不是颗粒状的灰色街道灰尘。

These bacteria can be found even in ordinary street dust, but that’s obviously not a prescription to introduce dust into your nutrition.

这种细菌连普通的街道灰尘里都找得到，虽然医师显然不会开灰尘这种营养处方给你。