Clean Air Status Trends Network

Project Description
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

[Summary provided by EPA]