Sources subject to an existing source performance standard must install, calibrate, operate and maintain continuous monitoring: opacity on fossil-fuel fired steam generators over 250 million Btu per hour (unless gas-only or qualifying oil firing), SO2 where such units have SO2 controls, NOx on units over 1,000 million Btu per hour in NO2 control regions (unless 30 percent below the standard), O2 or CO2 where needed for conversion; NOx on nitric acid plants over 300 tons per day in such regions; SO2 on sulfuric acid plants over 300 tons per day; opacity on fluid catalytic cracking regenerators over 20,000 barrels per day. Systems meet 40 CFR 60 Appendix B specifications, with traceable calibration gases reanalysed every six months, cycle times of six minutes (opacity) or 15 minutes (gases), daily zero and span checks, and quarterly excess emission and downtime reports; data are kept two years. Alternatives are possible for physical or extreme economic limits.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.