|
|
|
|
|
Why are sample results often reported as less than some number rather than "0"?
Sample results are often shown as "< 5.0 mg/l"? (read as less than five milligrams per liter). This is because the test method or test instrument (in this case, looking for the number of milligrams in each liter of sample) begins to detect the amount of a substance at some particular level that is more than zero. As test methods and test instruments evolve, they can detect substances at lower and lower levels. Thus, "< 5.0 mg/l" means that the substance was not detected but it might be present at some amount that is too small to detect.
|
|