Numerous studies have shown that air pollutants can cause deterioration of sensitive materials (Sherwood et al., 1990). This problem is particularly important for buildings and monuments, where materials are chosen for structural support as well as for their aesthetic value. Several types of deterioration have been documented, including discoloration, erosion of material, and changes in the physical and chemical make-up of the surface that lead to weakening of the structure and reduce aesthetic appeal.
Unfortunately, our understanding of the processes responsible for the deterioration is extremely limited. Such understanding is needed to assist in developing control strategies that minimize the damage and to help in designing new structures that will be less vulnerable to damage.
This research program has focused on a 42-story building that has been exposed to high levels of air pollutants over several decades. The building, known as the Cathedral of Learning, is a National Historic Landmark on the University of Pittsburgh campus. The building was constructed of Indiana limestone between 1929 and 1937, and is located in the densely populated Oakland area of Pittsburgh. Two sides of the Cathedral have extensive soiling; furthermore, the stone is eroded in several places. Since the time of construction, there have been numerous air pollutant sources within a few kilometers of the building. These include steel manufacturing plants that employ coke ovens and blast furnaces, a coalburning steam heating plant, heavy motor vehicle traffic, coal-burning railroads and riverboats, and a large number of domestic coal combustion sources such as home furnaces. The overall goal of this program is to improve our understanding of the processes responsible for air pollutant damage to the Cathedral of Learning.