The conventional explanation for this arrangement is that the glass fell to Earth first, then giant waves caused by the impact covered them with sediment, then iridium-containing dust settled out of the atmosphere over the course of a few weeks and formed the clay.

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He said the "tension" between health and safety and profit had caused the "lamentable problems" which had led to ceiling dust possibly containing asbestos falling to the shop floor when it was open.

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When pitching stores, hotels and restaurants, their demonstration often includes cutting open a paper tea bag, containing only broken leaves and tea dust, from a mass-market brand.

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The danger from nuclear waste comes mainly from dust-like particles containing radioactive isotopes of iodine, cesium and strontium that could be released if the reactor fuel is allowed to become too hot.

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