An air purifier or air cleaner is a device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke.
Functional schematic of an air purifier
A Sharp FU-888SV Plasmacluster air purifier.
The same air purifier, cover removed.
An air purifier placed under a table
Charcoal is a lightweight black carbon residue produced by strongly heating wood in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern charcoal briquettes used for outdoor cooking may contain many other additives, e.g. coal.
Charcoal
Packaging of charcoal for export in Namibia
An abandoned charcoal kiln near Walker, Arizona, US
Wood pile before covering with turf or soil, and firing it (c. 1890)