A pollutant or contaminant found within an environment should be defined as excessive, thus requiring action to reduce its concentration, only when its concentration in an area exceeds, by a certain multiple, its average concentration across its entire political jurisdiction (usually at the county level). Currently, many “maximum acceptable pollution concentration” regulations are based mainly upon the degree of harm such concentrations cause to biological organisms. Often, however, these limits are nearly the same or even lower than natural background levels. Depending on the distribution and nature of the pollutant, the type (i.e., size) of political jurisdictions used to construct an average would vary. Rarely would jurisdictions smaller than counties be used (cities, special districts, etc.) because they may just be too geographically small to calculate a reliable average of normal background pollutant levels. Counties may be the most appropriate jurisdiction to use because most land and watershed pollutants tend to be caused by point sources and remain within relatively small areas. Counties are also large enough to provide a statistically reliable sample for background pollution levels, but not so large that a geographically extensive sampling of pollution levels need to be mounted, at least for most pollutants, especially point source ones. However, widespread pollutants may require the use of state or perhaps even national averages to determine ‘normal’ background levels.
Generally, pollutants averaged over the predetermined geographic area should not require specific action to reduce it if its levels in all areas (within this predetermined geographic area) are at less than one standard deviation from normal. If an area has levels higher than one standard deviation, then specific action could be warranted to reduce the pollutant’s concentration in that location.
Pollutants defined as being ‘excessive’ in one jurisdiction could be reduced by increasing the penalty for each unit of that pollutant that is released within the jurisdiction. If it is found that the emission of a pollutant from one jurisdiction is causing ‘excessive’ readings in another, then the penalty per unit of that pollution should also be increased in the originating jurisdiction.