NPS monitors aerosols at Denali National Park and Preserve (DNPP) to calculate and track visibility trends (1988 to present). The aerosol program is part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) network. Wet deposi¬tion has been monitored at DNPP (Site ID AK03) since 1980 as part of the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). In order to estimate dry deposition at DNPP (Site DEN417), weekly concentrations of sulfur and nitrogen compounds have been measured since 1998 as part of the Clean Air Status and Trends Networks (CASTNet). UV-B radiation has been monitored at DNPP since 1997 as part of the EPA UV-B Monitoring Program. The NPS Western Air¬borne Contaminants Assessment Project (WACAP) is currently evaluating water, snow, sediments, willow bark, fish, and moose tissue in a number of western US and Alaska national parks, including DNPP, for the presence of metals (including mercury) and organic compounds.