A - C
CASTNET
The Clean Air Status and Trends Network (CASTNET) and the National Atmospheric Deposition Program (NADP) were developed to monitor dry and wet acid deposition, respectively. Monitoring site locations are predominantly rural by design to assess the relationship between regional pollution and changes in regional patterns in deposition. CASTNET also includes measurements of rural ozone and the chemical constituents of PM 2.5. Rural monitoring sites of NADP and CASTNET provide data where sensitive ecosystems are located and provide insight into natural background levels of pollutants where urban influences are minimal. These data provide needed information to scientists and policy analysts to study and evaluate numerous environmental effects, particularly those caused by regional sources of emissions for which long range transport plays an important role. Measurements from these networks are also important for understanding non-ecological impacts of air pollution such as visibil! ity impairment and damage to materials, particularly those of cultural and historical importance. CASTNET stations measure: 1. weekly average atmospheric concentrations of sulfate, nitrate, ammonium, sulfur dioxide, and nitric acid. 2. hourly concentrations of ambient ozone levels. 3. meteorological conditions required for caclulating dry deposition rates [For more information, link to "http://www.epa.gov/castnet/" [Summary provided by EPA]