NCPTT

Exposure Chamber

NCPTT operates a one-of-a-kind custom exposure chamber to study the interaction between air pollution and cultural materials.
(Photo: Unknown)

NCPTT operates a one-of-a-kind custom exposure chamber to study the interaction between air pollution and cultural materials. The chamber was designed and built in 1987 by the National Park Services (NPS) in partnership with the National Oceanic and Atmosphere Administration (NOAA) and the U.S. Geological Survey (USGS.) It was moved to NCPTT from Virginia in 1996.

The chamber is one of only three of similar capabilities in the world. It is a re-circulating wind tunnel that allows precise control of temperature, humidity, wind speed, pollution concentration, and turbulence. Up to eight samples such as limestone and marble, can be exposed at a time. Samples are typically exposed for 10 days under conditions comparable to Philadelphia in the springtime.

Following exposure, the samples are then shaken in a hydrogen peroxide solution to convert the absorbed sulfur dioxide to sulfates in solution. The resulting washes are analyzed upstairs in the Wet Lab via Ion Chromatography.