In-facepiece dust concentration is changed dozens of times in a matter of minutes due to changes of the size of the gaps between the mask and face. Source. A respirator is a device designed to protect the wearer from inhaling particulate matter, including airborne microrganisms, fumes, vapors, i.e. gases.
Why join Brainly? A community for students. Products of the neolithic culture Steel plows Boats with sails Domesticated dogs Wild figs. the answer would mostly likely be referring to things that actually were of use to the neolithic people and agriculture was the biggest thing making the answer steel plow. anonymous.
On this page is a nice selection of Mesolithic and Neolithic stone tools. The Mesolithic specimens are largely scrapers, knives and choppers, whereas the Neolithic are mostly arrow points that show a very good level of craftsmanship. The specimens represent several of the different North African cultures including some nice Predynastic Egyptian pieces, plus some material from stone age Britain.