2  Oct. 10, 2002  US 2002/0147433 Al  that there is frequently free urine ( e. g. not absorbed by the  absorbent article) and feces present adjacent to the wearer’s  skin surface. In such a situation, one must rely on the ability  of skin to maintain a free hydrogen ion concentration that  effectively counteracts basic ions present in such bodily  exudates. A limitation of this approach, therefore, is that in  order to be effective, the capacity of the skin to resist  changes in  pH  due to free urine and feces must be increased  by the application of  pH  control agents before the skin  actually comes into contact with the feces, ideally without  disturbing the skin’s own homeostatic pH balance.  [0007]  Diapers impregnated with skin lotions comprising  a buffer system are also known. For example, U.S. Pat. No.  5,525,346, issued to Hartung, et al. on Jun. 11, 1996  describes oil-in-water emulsions comprising a non-ionic  emulsifier, a dimethicone, sodium citrate, citric acid, aloe  vera, preservatives, and water. The patent further describes  diapers where at least the portion of the diaper that contacts  a wearer’s genitals and buttocks is impregnated with the  oil-in-water emulsion. While such diapers may provide a  skin care benefit, impregnating the diaper with such an  emulsion can substantially interfere with the functionality of  the diaper. For example, the portion of a diaper contacting a  wearer’s genitals and buttocks is also the portion of the  diaper that primarily receives bodily exudates, particularly  urine.  If this receiving area is impregnated with an emulsion  as is described in U.S. Pat. No. 5,525,346, the absorptive  properties thereof will be substantially compromised leading  to an increased risk of leakage. Further, given the aqueous  continuous phase of the skin lotion described in U.S. Pat.  No. 5,525,346, the absorbent elements of the diaper may  draw the aqueous phase away from the surface reducing any  skin care benefit provided by the lotion.  [0008]  Thus, there is a continuing need to counteract the  effects of ammonia and fecal enzymes on the skin of those  wearing absorbent articles. There is a further need to provide  improved absorbent articles that help maintain the  pH  of a  wearer’s skin in its natural acidic state more specifically,  between about 4.0 and about 6.0.  [0009]  The Applicants have discovered that it is possible  to help maintain an acidic skin pH by the use of proton  donating actives, such as buffer agents or acidic ammonia› neutralizing agents that transfer from an absorbent article to  a wearer’s skin. Particularly preferred materials are proton  donating actives that are effective in reducing the ability of  fecal enzymes to decompose urinary urea into ammonia in  addition to neutralizing any ammonia that may be present  adjacent to a wearer’s skin. A particularly preferred means  of delivering such ingredients is to incorporate them into a  skin care composition that transfers from the absorbent  article to a wearer’s skin carrying such proton donating  actives to the surface of a wearer’s skin.  [0010]  While the specification concludes with claims par› ticularly pointing out and distinctly claiming the present  invention, it is believed that the present invention will be  better understood from the following description in conjunc› tion with the following drawings, in which like reference  numbers identity identical elements and wherein:  [0011]  FIG. 1  is a plan view of an absorbent article of the  present invention in the form of a diaper.  [0012]  FIG.  2a  is a side view showing placement of the  skin analog used in the lotion transfer test.  [0013]  FIG.  2b  is a plan view showing placement of the  skin analog used in the lotion transfer test.  [0014]  I. Definitions  [0015]  As used herein, the term "comprising" means that  the various components, ingredients, or steps can be con› jointly employed in practicing the present invention.  Accordingly, the term "comprising" encompasses the more  restrictive terms "consisting essentially of’ and "consisting  of’.  [0016]  As used herein a "proton donating active" is a  substance or mixture of substances, that, when the substance  or mixture of substances is incorporated into a skin care  composition and applied to a subject’s skin as is described  in the Skin pH Reduction Test in the TEST METHODS  section below, causes a decrease in skin pH.  [0017]  As used herein, "an absorbent article comprising a  proton donating active" means any absorbent article, such as  those described below, typically having a liquid impervious  backsheet, a liquid pervious topsheet, and an absorbent core  positioned between the topsheet and the backsheet, wherein  the proton donating active is positioned within or on the  topsheet, and/or within or on the absorbent core, and/or  within or on the backsheet, and/or within or on any other  portion of the absorbent article, including cuffs, side panels,  fasteners, and the like.  [0018]  As used herein, the term "skin care composition  comprising a proton donating active" refers to any compo› sition employed to transfer a minimum effective amount of  the proton donating active from an absorbent article to a  wearer’s skin to provide a therapeutic and/or protective skin  benefit for the treatment or prevention of skin conditions,  such as diaper dermatitis. Representative materials are dis› cussed in detail below.  [0019]  As used herein, the term "wearer-contacting sur› face" of an absorbent article is one or more surfaces of any  article components that may contact the wearer’s body at  some time during the wear period. Body contacting surfaces  include, but are not limited to, portions of the topsheet, leg  cuffs, waist region, side panels, and the like, which may  contact a wearer during use.  [0020]  Other terms are defined herein where initially dis› cussed.  [0021]  With respect to proton donating active (s) and/or a  skin care composition (s), all percentages, ratios and pro› portions used herein are by weight unless otherwise speci› fied.  [0022]  II. Absorbent Articles  [0023]  As used herein, the term "absorbent article" refers  to a device which absorbs and retains body exudates. The  term "disposable" is used herein to describe absorbent  articles which are not intended to be laundered or otherwise  SUMMARY OF THE INVENTION  BRIEF DESCRIPTION OF THE DRAWINGS  DETAILED DESCRIPTION OF THE  INVENTION 