green air
n.β Β«The days ahead appear to offer more of the same “green air”βthe term is derived from the green color code that denotes clean airβthat settled into the region following the passage of Fridayβs cold front.Β» ββAir quality improving” by Thomas Fraser Daily Times (Maryville, Tenn.) Sept. 17, 2005. (source: Double-Tongued Dictionary)