(a) No person may cause, suffer, allow, or permit emissions of sulfur dioxide (SO[sub]2[/sub]) from any sulfur recovery plant to exceed the emission limits specified for stack effluent flow rates less than or equal to 4,000 standard cubic feet per minute (scfm) as determined by the equation:(b) If a source has an effective stack height less than the standard effective stack height determined for stack effluent rates less than or equal to 4,000 scfm by the equation:then, the allowable emission limit in subsection (a) of this section must be reduced by multiplying it by the short-stack reduction factor.