To What Extent Does Acid Precipitation Affect Annelids? In order to truly understand acid rain and it's eventual effect on earthworms, it would be best to look at the causes of acid rain. How and why does altered acidity in precipitation have a devastating effect? Acid rain is charecterized as "Precipitation that has a pH lower than about 5.0" (Allaby, Michael (1994) Ecology, Oxford Press,). Acid rain is created by many things, of which pollution from cars contributes the most. Ever since the Industrial revolution, the acidity of rain has been haywire. Sulfur an