The Department of Natural Resources amended Mo. Code Regs. Ann. tit. 10, §6.020, Air Quality Standards, Definitions, Sampling and Reference Methods and Air Pollution Control Regulations for the Entire State of Missouri. Changes add necessary definitions and delete obsolete ones. See http://www.sos.mo.gov/adrules/moreg/current/v38n1/v38n1f.pdf (pp. 106-23).