The slightest agitation, wherever it occurs, sets in motion the dust whose weight in the universe has been determined to be at least equal to that of the celestial bodies. We live in a feverish, agitated age, which makes certain types of dust particularly dangerous, but we have the means to protect ourselves. Industrial dust is dangerous, causing a lung disease called silicosis. Franju takes us to a number of particularly dangerous industrial sites (the flax industry, pebble crushing, porcelain manufacture, tunnel drilling, the charcoal industry) where people are highly exposed, and discusses the means available to combat this danger. Franju’s intention was not to make a simple prevention film, but to present the difficult jobs and working conditions in a sensitive and dramatic way.