Old English broc garment for the legs and trunk; see breeches). The sense might reflect the breeches sense, on the notion of two limbs or of appliances used in pairs. The typographical bracket is first recorded 1750, so called for its resemblance to double supports in carpentry (a sense attested from 1610s). Senses affected by Latin brachium arm..
Carbon dioxide, a greenhouse gas, is the main pollutant that is warming Earth. Though living things emit carbon dioxide when they breathe, carbon dioxide is widely considered to be a pollutant when associated with cars, planes, power plants, and other human activities that involve the burning of fossil fuels such as gasoline and natural gas.
Pollution point sources are identical to other physics, engineering, optics, and chemistry point sources and include: Air pollution from an industrial source, rather than an airport or a road, considered a line source or a forest fire which is considered an area source, or volume source.