The definition of public receptor is "offsite residences, institutions (e.g., schools, hospitals), industrial, commercial, and office buildings, parks, or recreational areas inhabited or occupied by the public at any time without restriction by the stationary source ..." Offsite is further defined to include "areas within the property boundary [of the stationary source] to which the public has routine and unrestricted access..."(40 CFR §68.3). If a company has a property boundary with no fence, but with many "no trespassing" signs, would the "no trespassing" signs be enough to justify restricted access, and thus make the area inside the signs considered onsite?

In most cases "no trespassing" signs will not be enough to consider the area inside the signs on- site. Generally, to be considered onsite, access should be physically restricted (e.g., the site is fenced, and security guards are on duty or badges are needed to gain entry). However, every facility must look at its own situation and make a reasonable determination as to whether access is really restricted. The facility should document its decision.