Where I worked in aerospace (missile guidance systems) a so-called "clean room" is essential for assembly of the equipment. When it all started in the 1950s the Navy built us a factory with a state of the art clean room. It was a hermetically-sealed and slightly pressurized area, with very fancy air circulation and filtering systems. When you went in you had to don white coveralls, a cap, and booties. Entry was via an air-lock where a blast of air was directed over you. The air quility was tested three times a day. In spite of all this it proved difficult to maintain the required air purity. Over the years an entirely different aproach has replaced the traditional clean room. It is called a "laminar flow work station". The room is simply built and maintained to normal office standards. However the workbench is semi-enclosed under a hood, and smoothly flowing filtered air is constantly blown over it. Air quality at the only place which matters, where the hardware is being assembled, is much better than what was achieved by the elaborate clean room that was state of the art in 1955.
Unfortunately a laminar flow workstation does not fit in well with the typical home decor.