español term (edited): de mayor a menor concentraci�n

It's hard to say exactly without knowing to what "concentration" refers, but if it's a pesticide, for example, you would talk about measuring the *level* of concentration (i.e., absolute numbers) versus the types of risks that it can pose (i.e., the effects it can cause). If it's radio waves, then you would probably say *degree* of concentration. This would be the case if I'm interpreting "concentration" as it's used in your text.