Naturally occurring biological materials such as mold, fungi, and/or pollen are not regulated by any government agency.  Currently mold, pollen and/or fungi have no established Threshold limit value (TLV). Threshold limit values (TLVs) are guidelines established by the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs refer to airborne concentrations of substances, and represent conditions under which it is believed that nearly all workers may be repeatedly exposed without adverse health effects.

Current industry practice suggests that differentiation of indoor to outdoor air sample analysis may indicate a degradation of indoor air quality. Outside air samples (control samples) are taken as comparison to inside air samples. Inside spore counts should be lower than that of outside spore counts. Somewhat barbaric once you consider the fact that weather, timing, methodology, media and location heavily skew the end result.

So, the amount of mold you or I can be exposed to before experiencing an adverse health effect is dependent upon your own disposition. Which raises the question, is the general mold test subjective? Yes, it is. It is the interpretation of results compounded with visual evidence and moisture readings that creates positive correlation. You may save money by finding the cheapest testing company, but you may want to consider if that money has in fact been wasted on numbers without reason.